# Do Americans use metric system?



## The Basket (May 21, 2019)

Just askin.
Seems they do and don't.


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## GrauGeist (May 21, 2019)

We do and we don't - in otherwords, it depends on where measurements are being applied. 

In areas of technical production (military, automotive, etc.), we use metric.

In home building, food packaging, driving distances and speeds, etc., we use the old system

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## mikewint (May 21, 2019)

As of 2019 the United States is one of only three countries (the other two are Myanmar and Liberia) that have not officially adopted the metric system as the primary means of weights and measures.
Even back in the early 60's the military was using metric, i.e. KLICKS and the little AR was not called a .22 caliber but a 5.56mm. Cars on the other hand were Detroit-made and all SAE. About the 70's there was that occasional PIA nut/bolt that got stripped 'cause my wrench didn't fit. About the 80's or so you had to have metric sized tools to work on just about anything. In the supermarket it's a weird mix. Soda pop is sold both ways, the big 2 L bottles and the smaller 12 fl.oz cans.
Meats still in English POUNDS and dry packaged items in weird English OUNCES like 12 3/4 oz making "cost per ounce" comparisons very difficul. Cooking/baking recipes still call for CUPS, TEASPOONS, and TABLESPOONS though most measuring cups are calibrated in metric units as well
Distances still in MILES, FEET, and INCHES. Interstate highways had both Miles and Kilometers for a while but they gave up on that. Speeds in MPH or MILES PER HOUR
I do not see the US truly going metric in the foreseeable future. Personally I think we would be better off joining the rest of the civilized world, more for the sake of interchangeability though I do feel that the metric system makes more sense than the "length of Charles I foot as he left church services one morning" or "3 Barley corns laid end to end". While I am making wishes, I want a pony.

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## vikingBerserker (May 21, 2019)

I know our military has been using metric since the 1930's

Right now I am drinking a Dr Pepper that is marked as "16.9 FL OZ (500 mL)"

But sometimes we use both for the same thing, you can buy milk in half pints/pints/quarts/gallons, or 500ml/1 Liter. 

It's really confusing at times, but at least we don't sell milk in bags...………………..

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## mikewint (May 21, 2019)

Yea, I've seen that mix in the bigger plastic bottles of pop though I tend to stick to the 2 L as they drop to 88 cents from time to time. Never seen the 1 L milk around here just gallon, 1/2 Gal and 1 qt
Gasoline by the gallon still


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## pbehn (May 21, 2019)

A football pitch (soccer) is imperial wherever you go, and the most universal measure, time, is a system that the Brits would be proud of.

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## vikingBerserker (May 21, 2019)

Now that I had no idea. What do the world's flight controllers use? I know they have to speak English but in the movies they always talk about altitude in thousands of feet.


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## Wurger (May 21, 2019)

Depending on the airspace defined, either the flight levels or feet. Actually the flight levels are nothing more but the altitude measured in thousands feet. Eg.. FL 100 = 10000 feet, FL80 = 8000 feet,. Usually the flight levels are used for high filghts while feet are for low ones.

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## mikewint (May 21, 2019)

Time measurement have very little to do with the Brits. The 24 hour day dates back to the Egyptians who had a 10 hour day, a 12 hour night and a twilight hour at the end and beginning of each 10 hour day. The Egyptians followed 36 constellations or decans as they rose one after another in the night sky 40 minutes apart. Obviously Egyptian "Hours" varied in length from season to season. 
The divisions of hours into 60 parts or minutes comes from the Babylonians who used a base 60 system of numbers (thus the 360 degrees in a circle). The Babylonian year also had 360 days in it.
Metric time would be difficult to fit into the present system of 24/60/60. Metric is base 10 so you have only 3 options for a day 10/100/1000 none of which work very well. In 1998 a Swiss watch company Swatch proposed Internet Time (a metricized system) wherein a day would be divided into 1000 "beats". With our present system that makes a "beat" = 1 min & 26.4 sec. Not noticed a whole lot of people jumping on that proposal.
As an aside a MOONTH or synodic month is full or new moon to full or new moon which averages 29.53 days another non-fit with the Earth solar orbit.
AND...7 days in a week (again the Babylonians) because there are 7 astronomical objects that travel across the sky: The day of the SUN(day); The day of the MOON(day); The day of SATURN(day). Mars, Jupiter, Venus, and Mercury lost their days to the Anglo-Saxon/Norse gods. Dies Martis or Mars (god of war) Day to TYW the Anglo-Saxon god of war TYW's Day; Dies Mercurii (messenger of the gods) lost out to Woden (Saxon top god) WODEN's day. The Germans held tight to their Carolingian leaders of the Holy Roman Empire and called it MITTWOCH ; Dies Lovis (Jupiter top god) lost out to Thor god of storms and "THUNder" so THOR's day; and Dies Veneris (Venus goddess of love) lost out to the Norse goddess FREYJA associated with love, sex and beauty so FREYA's day

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## pbehn (May 21, 2019)

mikewint said:


> Time measurement have very little to do with the Brits.


I said a sytem the Brits would be proud of, a mixture of bases from 60, 24, 7 and then a confusing number of weeks and months. The Japanese had a different system for time I presume the Chinese did too.


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## pbehn (May 21, 2019)

vikingBerserker said:


> Now that I had no idea. What do the world's flight controllers use? I know they have to speak English but in the movies they always talk about altitude in thousands of feet.


The goal in football is 8 yards by 8 feet, the boxes are 6 yards and 18 yards from the goal line, the radius of circle and semicircles are 10 yards and the penalty spot 12 yards from the goal. There originally was no specified length and width but a range 70 to100yds wide and 100 to 130 yds long. So theoretically it could have been played on a 100 yard square. There is now a standard size of 105m x 68m for new grounds but the old grounds still have smaller pitches due to the construction of the stands. They are all now quoted in metric of course but they are converted from the imperial.

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## Bucksnort101 (May 21, 2019)

Well, I know when I've worked on every car I've ever owned I not only have to drag out every standard tool I own, I also need to lug out all the metric ones as well. I think whomever engineers autos just likes to throw a little bit of everything on them just to pi$$ me off!!!


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## The Basket (May 21, 2019)

So on the F-35 there ain't no inches, cubits or fluid ounces? How sad.
How many miles does it get to the hogshead?

In the UK its also a mash up. But young people use metric whearas the old timers use inches.


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## gumbyk (May 21, 2019)

Bucksnort101 said:


> Well, I know when I've worked on every car I've ever owned I not only have to drag out every standard tool I own, I also need to lug out all the metric ones as well. I think whomever engineers autos just likes to throw a little bit of everything on them just to pi$$ me off!!!



That's just because the US refuses to modernise. US parts are imperial, the rest are metric.
Working on AS-350 helicopters, was the same. The engines were imperial, airframe metric.

The irony is that the official definition of an inch is a reference to centimetres... Which Inch?

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## Greg Boeser (May 21, 2019)

mikewint said:


> Dies Veneris (Venus goddess of love)


So, that's where venereal disease comes from!
That's what I love about this site. Ya learn something new everyday!

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## special ed (May 21, 2019)

Much the same as the UK, the young people learn metric along with Imperial. We dinosaurs will continue with what's familiar, bending as necessary to look for a 10mm wrench.


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## gumbyk (May 21, 2019)

special ed said:


> Much the same as the UK, the young people learn metric along with Imperial. We dinosaurs will continue with what's familiar, bending as necessary to look for a 10mm wrench.


My 7-year-old bounces between units - inches, feet, metres. Not sure what his teachers think of it!


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## fubar57 (May 21, 2019)

Being a child of the "change", I'll use metric or imperial depending who I'm talking to. I've used both in the same sentence, temperature and distance. In the papermill for 22 years, our paper roll diameters were inches and the widths were centimetres.

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## gumbyk (May 21, 2019)

fubar57 said:


> Being a child of the "change", I'll use metric or imperial depending who I'm talking to. I've used both in the same sentence, temperature and distance. In the papermill for 22 years, our paper roll diameters were inches and the widths were centimetres.


I'm much the same, except I can't understand Fahrenheit. That's where my son gets it from.
It gets worse when talking distance - 'Miles' can be either statute miles or nautical miles, so I'll talk in one of three units (two of which are miles)


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## special ed (May 21, 2019)

Fortunately, in the US thermometers have both scales.


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## pbehn (May 21, 2019)

The worldwide oil and gas industry discusses pipe diameter in inches and then orders them in millimetres, the length is of course always in meters except on the final invoice which is in feet and inches and meters (of course).


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## MIflyer (May 21, 2019)

We use Metric when we have to and American (can't call it English no more) when we have to. The local AWOS station at the airport reports wind speed in knots, visibility in miles, cloud heights in thousands of feet, atmospheric pressure in inches of Mercury, and temperature in Celsius. Speed of passing aircraft, when provided, is in furlongs per fortnight.

As for Deg F and Deg C, conversion is incredibly easy. 

16C = 61F

28C = 82F

So all you have to do is swap the numbers and you have it!

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## gumbyk (May 21, 2019)

special ed said:


> Fortunately, in the US thermometers have both scales.


Yeah, here too. But if someone tells me it's 50ºF, I have no idea how hot or cold that is... (unless it's -40)


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## pbehn (May 21, 2019)

MIflyer said:


> We use Metric when we have to and American (can't call it English no more) when we have to. The local AWOS station at the airport reports wind speed in knots, visibility in miles, cloud heights in thousands of feet, atmospheric pressure in inches of Mercury, and temperature in Celsius. Speed of passing aircraft, when provided, is in furlongs per fortnight.
> 
> As for Deg F and Deg C, conversion is incredibly easy.
> 
> ...


The British use deg C for cold and deg for hot. So minus 10 is cold and 90 is hot, only the weather forecasters ever actually name the units. The linesmen at Wimbledon can take their jackets of at 90F.


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## gumbyk (May 21, 2019)

pbehn said:


> The worldwide oil and gas industry discusses pipe diameter in inches and then orders them in millimetres, the length is of course always in meters except on the final invoice which is in feet and inches and meters (of course).


That's because most pipe is manufactured to U.S. specifications (which is imperial, but metric nominal), so 25mm pipe is actually 1 inch (25.4mm).
I needed to buy 6mm copper pipe once, and it took almost a week to actually find some that wasn't 1/4 inch.


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## mikewint (May 21, 2019)

gumbyk said:


> t gets worse when talking distance - 'Miles' can be either statute miles or nautical miles,


If it were only that simple. You missed: Roman mile, Italian mile, Arabic mile, Irish miles, English mile, Welsh mile, Scots mile, Irish mile, International mile, U.S. survey mile, Geographical mile, Metric mile, and Scandinavian mile
In 1754 Daniel Fahrenheit wished to exclude negative numbers since they made little sense,i.e. less than no temperature. In addition they were difficult to use correctly in mathematical formula. Therefore he made his zero the coldest temperature he could achieve at the time which was a concentrated salt, ammonium chloride, and ice mixture. His second fixed point was the blood temperature of a healthy man which he determined from a earlier temperature scale to be 90 on his new scale. He then adjusted his scale to make ice melt at 32 degrees and that put body temperature at 96. Using his new thermometer he found that water boiled at a constant temperature of 212 degree. After Anders Celsius published his metric temperature scale with fixed points at freezing/melting point of ice and boiling point of water the Royal Society fixed Fahrenheit's scale at the same points +32 degrees for the freezing point and 212 degrees for the boiling point. That gives the Fahrenheit scale 180 degrees between the two point rather than the 100 degrees on Celsius' scale and humans an oral temperature of a bit above 98 degrees

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## pbehn (May 21, 2019)

gumbyk said:


> That's because most pipe is manufactured to U.S. specifications (which is imperial, but metric nominal), so 25mm pipe is actually 1 inch (25.4mm).
> I needed to buy 6mm copper pipe once, and it took almost a week to actually find some that wasn't 1/4 inch.


Well sort of, that's the way it used to be, its just in conversation it is much easier to discuss in inches without making a misunderstanding. It is just a nominal size anyway the actual size on the technical documents isn't usually any precise inch size. For insurance on most contracts the pipe must carry the API logo and that determines the use of "Imperial" sizes on documentation, Depending on how they are made they are sized on the outside or the inside which is a bit of a nightmare when you have to weld them together as sometimes happens.


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## MIflyer (May 21, 2019)

Actually, for use in aircraft I made a Knots to MPH conversion chart, since ASI gauges can be either one. Cessna 150's usually have MPH and Cessna 152's have Kts.

Then, for conversion challenges not well met, we have the case of the Gimli Glider.,....

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## wuzak (May 21, 2019)

pbehn said:


> The irony is that the official definition of an inch is a reference to centimetres... Which Inch?



That article touches on the fact that all main imperial units are no defined by their relationship to metric units.


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## gumbyk (May 21, 2019)

wuzak said:


> That article touches on the fact that all main imperial units are no defined by their relationship to metric units.



Yeah, and now the metric system is being redefined to align with physical constants, e.g. a metre is determined by the distance light travels in a vacuum in 1/299792458 of a second. A second is determined by the time it takes for a caesium atom to oscillate 9,192,631,770 times. The kilogram has just been redefined in terms of Planck's constant.

Apparently they found that the reference kilogram was gaining mass (or all the others were losing it).

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## GrauGeist (May 22, 2019)

When I was in southern/eastern Europe several years ago, I was asked what I thought of the 130 kph speed limit for most of the highways there by a local because they heard we had lower speed limits and I smiled and said "that's only 80 miles an hour...that's about the same for many of our highways"


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## DerAdlerIstGelandet (May 22, 2019)

We do in our job, but that is because we have European Helicopters in our fleet.

I prefer metric. It is easier and better.

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## GrauGeist (May 22, 2019)

By the way, in the world of mechanics, there is a slight difference between SAE tools and Metric tools.

It's the 10mm socket that always disappears. Always.
However, in the realm of SAE, it's always the dang 7/16" socket that gets drawn into the mysterious void of missing socks and car keys....

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## buffnut453 (May 22, 2019)

I just wish my fellow Americans would learn how to spell metre!😀😀😀


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## vikingBerserker (May 22, 2019)

*meter

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## special ed (May 22, 2019)

I thought it was metre only in France. My spell check prefers meter.

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## tyrodtom (May 22, 2019)

I work on a lot of old cars, so I have to keep my SAE tools handy, as well as metric.

I've had a new mechanic ask me which is bigger ? 7/8ths, or 15/16s.
The new ones have a easier time with metric, but sorta lost with the fractions of SAE sizes.

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## MIflyer (May 22, 2019)

I'll tell you one thing that makes no freakin' sense whatsoever in Metric.

Screw threads!

Example: 1/4 -28 - anyone can understand that. 1/4 in dia, 28 threads per inch, fine thread, We also have 1/4 - 20, course thread.

But Metric screw threads? Fugetaboutit!

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## MIflyer (May 22, 2019)

My Volt Ohm Metre uses Metric measurements..

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## mikewint (May 22, 2019)

if someone tells me it's 50ºF, I have no idea how hot or cold that is
Gum-
You can get reasonably close if you recall that from freezing to boiling (water) there are 100 degree intervals Celsius and 180 degree units Fahrenheit Sooo...a Fahrenheit degree is _about_ half a Celsius degree or the reverse a Celsius degree is_ about _twice a Fahrenheit degree. The single point of complication is that 32 degree Fahrenheit tail, i.e. the zero marks do not align. Sooo... remove the tail -> 50 - 32 = 18 then divide by 2 -> 18 / 2 = 9 So 50F is _about _9C. Pretty darn close. In actual fact it is 10C.
Since the actual ratio is 1.8 the error increases as you get higher on the Fahrenheit scale 212F - 32 = 180 / 2 = 90 Whereas it should be 100


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## MIflyer (May 22, 2019)

"...if someone tells me it's 50ºF, I have no idea how hot or cold that is ... "

That is because it is neither.

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## mikewint (May 22, 2019)

MIflyer said:


> That is because it is neither.


Well not exactly...It is one or the other _as soon as _the reference temperature is stated


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## MIflyer (May 22, 2019)

"...It is one or the other _as soon as _the reference temperature is stated"

No, it depends on how much clothes you have on. I recall waiting for a Shuttle launch out on the causeway at 0500, 56F with a 17 kt wind blowing out of the NE (which scrubbed the launch). I could not believe that 56F could be so damn cold.


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## gumbyk (May 22, 2019)

MIflyer said:


> "...if someone tells me it's 50ºF, I have no idea how hot or cold that is ... "
> 
> That is because it is neither.


Just asked google... it's 10ºC - that's cold.

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## mikewint (May 22, 2019)

OK, so we're talking about the PHYSICAL sensation of hot and/or cold. The human skin does indeed have neurons that react not to heat but to heat LOSS and heat GAIN.
In the case you mentioned your temperature sensors were NOT reacting to the actual temperature but to the rapid loss of heat from your body as heat was carried away by the wind. That's why they post a "FEELS LIKE" temperature or "WIND CHIIL" generally speaking in the colder months. 
One can easily go into hypothermia in 75F water due to the rapidity with which water conducts heat. In Vietnam during the monsoons it was easy to slip into hypothermia during +85F temperatures as wet clothing and wind carried heat rapidly from the body. 
Those same neurons, like any other sensory organ can adapt to a continual sensory input (my house smells OK but yours stinks). 
Put out three bowls of water one hot, one lukewarm, and the third cold water. Put one hand in the hot and the other in the cold. Let them adapt for 5 min or so. Now put both hands in the lukewarm water. To the hot hand it will feel cold and to the cold had it will feel hot. 
Thermometers were developed BECAUSE of humans inability to sense actual temperatures


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## pbehn (May 22, 2019)

mikewint said:


> OK, so we're talking about the PHYSICAL sensation of hot and/or cold. The human skin does indeed have neurons that react not to heat but to heat LOSS and heat GAIN.
> In the case you mentioned your temperature sensors were NOT reacting to the actual temperature but to the rapid loss of heat from your body as heat was carried away by the wind. That's why they post a "FEELS LIKE" temperature or "WIND CHIIL" generally speaking in the colder months.
> One can easily go into hypothermia in 75F water due to the rapidity with which water conducts heat. In Vietnam during the monsoons it was easy to slip into hypothermia during +85F temperatures as wet clothing and wind carried heat rapidly from the body.
> Those same neurons, like any other sensory organ can adapt to a continual sensory input (my house smells OK but yours stinks).
> ...


That is a matter of opinion, there are 7.5 billion of them all maintain the same body temperature from the arctic to equator and for periods of up to 110 years.


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## gumbyk (May 22, 2019)

mikewint said:


> OK, so we're talking about the PHYSICAL sensation of hot and/or cold.



The whole concept of HOT or COLD is only about a physical sensation. There is no concept of 'HOT' in a scientific term


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## buffnut453 (May 22, 2019)

special ed said:


> I thought it was metre only in France. My spell check prefers meter.



The international unit of measure is the metre and _should_ be used globally (IMHO). In British English, a meter is a device used for measuring something (eg speedometer, gas meter, electric meter etc).

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## gumbyk (May 22, 2019)

special ed said:


> I thought it was metre only in France. My spell check prefers meter.



You don't get a say in how its spelt if you don't use the unit.

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## special ed (May 22, 2019)

I pointed out in another thread the only reason we have the decimal system is because we have ten fingers and toes. If everyone had six fingers per hand we would have learned to count and use math in another system. Also, 10 is evenly divisable by only two whole numbers while 12 is evenly divided by 100 per cent more, i,e, 2,3,4,and 6.


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## Jeff Hunt (May 22, 2019)

mikewint said:


> Yea, I've seen that mix in the bigger plastic bottles of pop though I tend to stick to the 2 L as they drop to 88 cents from time to time. Never seen the 1 L milk around here just gallon, 1/2 Gal and 1 qt
> Gasoline by the gallon still


And that would be a US gallon which is smaller than an Imperial gallon.


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## Zipper730 (May 22, 2019)

In the US, the scientific, medical, military, and drug-dealing community uses metric: It puts Breaking Bad into a new perspective


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## mikewint (May 22, 2019)

gumbyk said:


> There is no concept of 'HOT' in a scientific term


There is in a relative sense. If we have two bars of metal and (A) is at a temperature of 100F and bar (B) is at 90F then by all means scientific or non it is perfect correct to say that bar (A) is hot _in comparison _to bar (B). Like other relative terms HIGH -LOW; GOOd - BAD; TALL - SHORT they take meaning only _with respect to each other_



pbehn said:


> That is a matter of opinion, there are 7.5 billion of them all maintain the same body temperature from the arctic to equator


And that is a big NOPE. Human body temperature averages 98.6F/37C BUT that is a AVERAGE temperature and you may never have exactly that temperature or have in transiently at points during the day/night. Age, activity, external temperature, time of day cause temperature swings from 97F(36.1C) to 99F(37.2). Temps above 100.4F(38C) generally signal a fever which can rise to 102F(38.9) to 103F(39.4) in the normal course of the fever. 105F(40.5) and above signal a severe fever with potential brain damage.
During any and all of these gyrations those neurons that sense heat movement in and out of the body play no role whatsoever. On the body (axon) of these neurons are pores (ion channels) that can be opened (allowing an influx of ions) at specific temperatures. In 1997 a specific ion channel TRPV1 that opens at temperatures above 108F(42.2C) was discovered. As ions rush into the suddenly opened ion channel the change in potential causes the neuron to fire carrying the signal to the brain. 
The actual "thermostat" of the body is a small portion of the brain known as the hypothalamus. Through its coordination of the autonomic nervous system it responds to external and internal stimuli to regulate body temperature. It regulates the activities of the skin, sweat glands, and blood vessels to regulate body temperature.
Sweating with the accompanying evaporation of water (an endothermic process) acts to remove heat from the body. An electric fan moves air (actually heating it a bit in the process) which increases the rate of evaporation or heat loss. Hence the sensing neurons report a cooling sensation. A metal plate and a piece of wood are at the same temperature but touching the metal (an excellent conductor of heat) it will feel cool while the wood (a non-conductor) will feel warm. The water for sweat is stored in the dermis (skin layer #2). When/if this layer becomes depleted sweating stops, evaporation ceases and body temperature rises rapidly. The term is heat stroke and can prove fatal


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## swampyankee (May 22, 2019)

I compartmentalize, in that I do physics (which I teach) in SI (not just "metric"  ), but did most engineering in US Customary (degrees Rankine, pounds-force and slugs) and live my everyday life in a slightly different subset of US Customary. (degrees Fahrenheit and pounds.


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## pbehn (May 22, 2019)

mikewint said:


> There is in a relative sense. If we have two bars of metal and (A) is at a temperature of 100F and bar (B) is at 90F then by all means scientific or non it is perfect correct to say that bar (A) is hot _in comparison _to bar (B). Like other relative terms HIGH -LOW; GOOd - BAD; TALL - SHORT they take meaning only _with respect to each other_
> 
> 
> And that is a big NOPE. Human body temperature averages 98.6F/37C BUT that is a AVERAGE temperature and you may never have exactly that temperature or have in transiently at points during the day/night. Age, activity, external temperature, time of day cause temperature swings from 97F(36.1C) to 99F(37.2). Temps above 100.4F(38C) generally signal a fever which can rise to 102F(38.9) to 103F(39.4) in the normal course of the fever. 105F(40.5) and above signal a severe fever with potential brain damage.
> ...


The fact is, that the human body is better at maintaining its temperature at a constant than the "constants" that the Celsius scale is based on. Water can exist at minus 40C under some conditions and at 20,000 ft water boils at 83 deg C. There is a variation in temperature with every person, but each person during a day is remarkably uniform to about 0.5C. Women have a greater variation with ovulation and pregnancy but again the variation is constant. seven and a half billon produced with this temperature control is remarkable.


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## MiTasol (May 22, 2019)

mikewint said:


> If it were only that simple. You missed: Roman mile, Italian mile, Arabic mile, Irish miles, English mile, Welsh mile, Scots mile, Irish mile, International mile, U.S. survey mile, Geographical mile, Metric mile, and Scandinavian mile
> In 1754 Daniel Fahrenheit wished to exclude negative numbers since they made little sense,i.e. less than no temperature. In addition they were difficult to use correctly in mathematical formula. Therefore he made his zero the coldest temperature he could achieve at the time which was a concentrated salt, ammonium chloride, and ice mixture. His second fixed point was the blood temperature of a healthy man which he determined from a earlier temperature scale to be 90 on his new scale. He then adjusted his scale to make ice melt at 32 degrees and that put body temperature at 96. Using his new thermometer he found that water boiled at a constant temperature of 212 degree. After Anders Celsius published his metric temperature scale with fixed points at freezing/melting point of ice and boiling point of water the Royal Society fixed Fahrenheit's scale at the same points +32 degrees for the freezing point and 212 degrees for the boiling point. That gives the Fahrenheit scale 180 degrees between the two point rather than the 100 degrees on Celsius' scale and humans an oral temperature of a bit above 98 degrees



That is why I prefer metric over inferial (a common portmanteau word made from joining *infe*rior and impe*rial)*

I read years ago the reason that the US and Imperial Gallon are different is that when the US first laid down its standards in the late 1700s Britain was using three different gallons so the Yanks took the most common one in use and made it the US gallon. When the Brits later decided to have a standard gallon they (naturally) chose a different one.

Do not know if that is true but it is very British so probably is

MikeWint may know?


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## wuzak (May 22, 2019)

vikingBerserker said:


> *meter



A meter is a device for measuring or monitoring a


MIflyer said:


> My Volt Ohm Metre uses Metric measurements..



You mean your volt/ohm meter uses metric measurements.


pbehn said:


> The fact is, that the human body is better at maintaining its temperature at a constant than the "constants" that the Celsius scale is based on. Water can exist at minus 40C under some conditions and at 20,000 ft water boils at 83 deg C. There is a variation in temperature with every person, but each person during a day is remarkably uniform to about 0.5C. Women have a greater variation with ovulation and pregnancy but again the variation is constant. seven and a half billon produced with this temperature control is remarkable.



That's why the boiling (100C) and freezing points (0C) are defined at 1 atm pressure in the metric system.

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## MiTasol (May 22, 2019)

buffnut453 said:


> The international unit of measure is the metre and _should_ be used globally (IMHO). In British English, a meter is a device used for measuring something (eg speedometer, gas meter, electric meter etc).



Agreed and the US is the only country that mis-spells aluminium. Must be some of the British heritage rubbing off with the Brits way of being contrary on so many things (standards based on every number from 1 to 22 (or higher) and a whole lot of other strays like 112 thrown in to keep the confusion supreme


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## wuzak (May 22, 2019)

MiTasol said:


> I read years ago the reason that the US and Imperial Gallon are different is that when the US first laid down its standards in the late 1700s Britain was using three different gallons so the Yanks took the most common and made it the US gallon. When the Brits later decided to have a standard gallon they (naturally) chose a different one.



That is correct.



> Way back we had used the Queen Anne's gallon of 3.785l to measure wine. We also had different volumes and names to measure both beer and grain. When we realised that this was silly, in 1824, the UK chose a single imperial term and lumped together all three measurements, picking a roughly-average volume and calling it a gallon. American colonists, though, stuck to tradition and kept just the Queen Anne's volume for their own gallon definition.



US Gallons And Imperial Gallons - Why Are They Different?




> In 1824, Britain adopted a close approximation to the ale gallon known as the imperial gallon and abolished all other gallons in favour of it. Inspired by the kilogram-litre relationship, the imperial gallon was based on the volume of 10 pounds of distilled water weighed in air with brass weights with the barometer standing at 30 inches of mercury and at a temperature of 62 °F.



Gallon - Wikipedia

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## fubar57 (May 22, 2019)

gumbyk said:


> The whole concept of HOT or COLD is only about a physical sensation. There is no concept of 'HOT' in a scientific term



I think the scientific term for this is "HOT"

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## The Basket (May 22, 2019)

A few conversions I do are gallons to litres and kms to miles and how to work out distance and time to create mph. 

My car displays mpg but petrol is sold in litres so if I do 234 miles and my car does 50mpg average and petrol is £1.24 per litre, how many apples do I have? 

I remember reading that cannabis dealers could be prosecuted for selling drugs in ounces rather than actually selling illegal drugs. Probably just another stupid story. 

Problem is when is a litre a litre? A litre of petrol at 30 degrees Celsius is very different than at 0 degrees. So always buy petrol at night when it's cooler as you're getting more petrol! 

A pressurised suit is needed at altitude such as the U-2 pilots because the boiling point of water can become lower than the human body temperature so the water in your blood can turn to gas. That's not good! 

So boiling point of water is 100'C. OK... What type of water? Sea water? Is this at altitude? On the planet Mars?


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## wuzak (May 23, 2019)

The boiling point of water originally defined by the Celsius scale is 100°C at 1 standard atmosphere pressure. I don't know the water composition. 

Since the '50s the Celsius scale has been defined in terms of absolute zero and the triple point of a standard water composition at 1 standard atmosphere.

Since a couple of days ago, SI units have all been redfined in terms of physical constants.
BIPM - measurement units


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## MIflyer (May 23, 2019)

I read that when the folks at China Lake were developing the Sidewinder missile that they found that passive IR sensors could find when the various female employees were having their periods. When the girls found out about that they made a list of the data, gave it to the men and told them to cut it out. 

So the phrase "hot girls" has some scientific basis.

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## mikewint (May 23, 2019)

swampyankee said:


> I do physics (which I teach) in SI


I wondered if anyone would make this point. The so called METRIC system ended officially way back in 1960 when the International System of Units, universally abbreviated SI (from the French _Le Système International d'Unités_), was established by the 11th General Conference on Weights and Measures (_Conférence Générale des Poids et Mesures_). The term METER/METRE derives from Old English, reinforced in Middle English by Old French metre, from Latin metrum, from Greek metron meaning ‘measure’. You might recall that the term is/was in use prior to being taken over by the scientific community. Poetry and music have a rhythmic pattern of beats which is called their Meter/Metre. It can also be used to simply mean 'measure' as in "There is no metre to happiness"
Not to mention Water METERS; Gas METERS; Electricity METERS; and Parking METERS.
But I digress. The original idea behind the Metric System was born during the French Revolution. The New French Republic wanted to remove any and all vestiges of the monarchy. The French system of weights and measures was, at the time, like the English system, based on plethora of objects with no relationship to each other and like the Pied du roi, the Royal Foot. As long as they were starting over from scratch several well-known French scientists petioned to have the "New" system be based on 'imperishable' objects that were eternal and that any and everyone who wanted to had access to. In other words abandoning things like a bar of metal stored in a vault somewhere. The new system would also be a decimal system AND most importantly all units would relate directly to one another. 
Starting with the unit of length the METRE defined as 1/10,000,000 the distance from the equator to the north pole along the Paris meridian. Which the French actually measured (at least most of the accessible parts that were on land). The result was the METRE divided up into base 10 units. Volume was defined by constructing a CUBIC DECIMETER which is/was a LITRE. The the cubic decimeter/litre was filled with the Earth's most common substance WATER. One CUBIC MILLIMETER of pure water became the GRAM. Since a decimeter = 10 millimeters the cubic decimeter is 1000 cubic millimeters of one gram each or a cubic decimeter of pure water is one KILOGRAM.
As the Metric system gained in acceptance, the growing scientific community began to add more and more units of measure, Ampere, Henry, Weber, Torr, Atmosphere, Tesla, amu, lumen, angstrom, etc. As a result the 1960 conference ended the Metric system replacing it with the SI system decreeing that any and all measurements HAD to be derived from just seven base units: the *metre* for measurement of length, the *kilogram* for mass, the *second* for time, the *ampere* for electric current, the *kelvin* for temperature, the *candela* for luminous intensity, and the *mole* for amount of substance. Interesting to note that the former GRAM and LITER are no longer SI units.
This SI rule leads to simplification BUT forces the use of non-usable/inconvenient units of measure like the PASCAL for pressure. Under SI rules the unit of pressure, the PASCAL has to be FORCE per unit of AREA. In SI one NEWTON (Kilogram / s^2) of force / area of one square meter. A unit so tiny as to be totally impractical except maybe to measure mouse farts. The Earth's atmosphere exerts a pressure of 101,325 Pascals. The weather Guys who used to use the BAR ( one atm) and millibar now use hPa or hectoPascals. 100 hPa = 1 millibar. Materials and engineering are forced into Mega and even GigaPascals for the most common of substances.


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## OldParts (May 23, 2019)

I wish the U.S. would change because most science is done in scientific units. But if you don't know this store it is worth looking up: 

*Gimli Glider*


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## vikingBerserker (May 23, 2019)

It's the simple things in life......

Metric is just so much more logical to me.

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## buffnut453 (May 23, 2019)

vikingBerserker said:


> It's the simple things in life......
> 
> Metric is just so much more logical to me.



Entirely agree.

A propos of absolutely nothing, Alan Turing made a compelling argument that humans should adopt base 12 number system because of the ease of counting using the knuckles and tips of the fingers as the numerals, with the thumb being the counting pointer. While I admire the idea, I think it would drive me nuts!

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## swampyankee (May 23, 2019)

Just to pick a nit: a triple point is where solid, liquid, and vapor are in equilibrium; this happens at a specific temperature and pressure.


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## gumbyk (May 23, 2019)

The Basket said:


> Problem is when is a litre a litre? A litre of petrol at 30 degrees Celsius is very different than at 0 degrees. So always buy petrol at night when it's cooler as you're getting more petrol!


Most petrol tanks are stored underground, so end up without enough diurnal temperature variation to make a difference.

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## MIflyer (May 23, 2019)

I once bought a set of combination wrenches Made in India.

As near as I could tell they must have used the same forgings for the Metric and the SAE ones, because none of them with either exactly metric nor SAE.

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## gumbyk (May 23, 2019)

MIflyer said:


> I once bought a set of combination wrenches Made in India.
> 
> As near as I could tell they must have used the same forgings for the Metric and the SAE ones, because none of them with either exactly metric nor SAE.


Whitworth?


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## pbehn (May 23, 2019)

buffnut453 said:


> Entirely agree.
> 
> A propos of absolutely nothing, Alan Turing made a compelling argument that humans should adopt base 12 number system because of the ease of counting using the knuckles and tips of the fingers as the numerals, with the thumb being the counting pointer. While I admire the idea, I think it would drive me nuts!


The problem with people like Turing is that they cant imagine not being like they are. I am sure he could work in any base you care to mention, it doesn't mean the general public can. In fact the Chinese count to ten on one hand.


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## GrauGeist (May 23, 2019)

gumbyk said:


> Whitworth?


Tiawanese and Chinese toolsets had a combination of Metric, SAE and Whitworth sizes, too.


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## pbehn (May 23, 2019)

mikewint said:


> Materials and engineering are forced into Mega and even GigaPascals for the most common of substances.


 We used Mega Pascals which is the same as N/mm2 but easier to use for the same reason as it is easier to write MPa. than N/mm2 on here. It is just how the metric system is used 6,000 Km is just another, more convenient way of saying 6,000,000 metres.


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## mikemike (May 23, 2019)

I hope you all realize that where it concerns electricity, you have always been in metric/SI country exclusively, including all the modifiers: MilliVolt, MegaWatt, KiloOhm, MicroFarad and so on.

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## mikemike (May 23, 2019)

By the way, the IJAAF used metric, because they were established with the aid of a French technical mission, while the IJNAF used British haphazard, because they were tutored by Brits. That led to otherwise identical engines not being exchangeable between services, because the mounting and connecting hardware was incompatible. And while both Kawasaki (Army) and Aichi (Navy) license-built the DB601, you couldn't put an Aichi engine into a Ki-61 (that was considered when the Kawasaki factory was bombed), because all the screws, nuts, bolts and washers in the engines had different sizes. And while the Navy continued to use the British 7,7x56R cartridge, the Army developed a 7,7x58 in rimless AND semi-rimmed, just to be contrary, I guess.

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## wuzak (May 23, 2019)

mikewint said:


> This SI rule leads to simplification BUT forces the use of non-usable/inconvenient units of measure like the PASCAL for pressure. Under SI rules the unit of pressure, the PASCAL has to be FORCE per unit of AREA. In SI one NEWTON (Kilogram / s^2) of force / area of one square meter. A unit so tiny as to be totally impractical except maybe to measure mouse farts. The Earth's atmosphere exerts a pressure of 101,325 Pascals. The weather Guys who used to use the BAR ( one atm) and millibar now use hPa or hectoPascals. 100 hPa = 1 millibar. Materials and engineering are forced into Mega and even GigaPascals for the most common of substances.



1 bar = 100kPa

1 bar does not equal 1 atmosphere. 1 atmosphere is, in fact, 1.01325 bar.

Funny thing about MPa is that if you use mm for length units and N for force units you directly end up with MPa. You don't have to work with N and m to calculate Pa and then figure out how many MPa that is (not that that would be difficult).


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## XBe02Drvr (May 24, 2019)

Wurger said:


> Actually the flight levels are nothing more but the altitude measured in thousands feet. Eg.. FL 100 = 10000 feet, FL80 = 8000 feet,.


Well, sort of. In North America anyway (the rest of the world does weird stuff) altitudes lower than 18,000 feet are defined in feet referenced on local surface barometric pressure, while above that the Flight Levels are based on a constant 29.92 " HG standard atmospheric pressure. If we could only survive the transition, we'd be way better off to go with the rest of the world and switch the whole system over to "metric" units. It's only us brontosaurs that would be inconvenienced, the younger folk with more flexible minds would adapt readily.

Cheers,
Wes

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## XBe02Drvr (May 24, 2019)

buffnut453 said:


> In British English, a meter is a device used for measuring something (eg speedometer, gas meter, electric meter etc)


And a met*er* is a mental device used for measuring a linear distance.
And speaking of the confusion of tools needed to work on today's "global" machinery, I remember maintaining a fleet of Netherlands manufactured Fokker F27s of varying vintages with RR Dart engines made from 1947 to 1977, with Dowty props of varying ages, Lucas electrics, Maxaret antiskid, and Goodyear and Dunlop brake assemblies. SAE and metric tools weren't enough. You had to have British Standard and Whitworth as well. Sometimes you would get an older Dart with newer accessories on it and you'd wind up using Whit, BS, and metric all on the same job. Newer combustion cans on an older engine might have "updated" hardware installed...or not.
Cheers,
Wes

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## Elmas (May 24, 2019)

Many years ago I was involved in a big job, and one of the consultant structural Engineers was a Canadian.
Discussing about the stresses in a column I noticed that he was mentally translating data from Imperial to SI and he noticed that I was doing the same but from ST ( Sistema Tecnico, used by italian Engineers until twenty years ago).
_“D***n SI”_ was our mutual agreement _“could not things have stayed as they were, we Engineers were working so well, with that units…”_


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## mikewint (May 24, 2019)

wuzak said:


> 1 bar does not equal 1 atmosphere. 1 atmosphere is, in fact, 1.01325 bar.


Entirely and completely correct, I was speaking in generalities which is a bad thing, Es tut mir leid. the BAR at 100,000 Pa is NOT an accepted SI unit nor is it on the "accepted for use" non-SI units like the common units: Days (d); Minutes (min); Hours (h); the common angle units of Degrees, Minutes of Arc; and Seconds of Arc; for land the Hectare; the original metric Liter/Litre; and the metric Tonne. The SI does however say that while not "accepted" it is OK to use. As a result we hear/see a mix of hectoPascals, kiloPascals; and Bars except for the common weather guys who still report in atmospheric pressure in INCHES leaving out the "OF WHAT" part and many cases even the inches.



wuzak said:


> mm for length units and N for force units


That mixture of units gives you two separate length measurements m and mm^2 in the numerator and denominator respectively. The reason it works and comes out in M (Mega - million) is because 1 meter = 1000 mm and 1 m^2 is 1000mm x 1000mm = 1,000,000 mm^2. For calculations to remain valid with answers in the correct units you need to stay within a particular system, in this case, the MKS system or Meter-Kilogram-Second system of units.


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## mikewint (May 24, 2019)

XBe02Drvr said:


> Lucas electrics,


Ah yes how well I remember LUCAS, Lord of the Dark


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## mikewint (May 24, 2019)

buffnut453 said:


> Alan Turing made a compelling argument that humans should adopt base 12 number system


If you really stop and consider it the recurring nature of 12 is really astounding: A ruler has 12 subdivisions. The Romans also divided the foot into 12 divisions and the UNCIA was 1/12th of a Roman pound.. Produce like eggs. donuts, flowers, golf balls, beer, soft drinks ( a case is 24 cans), etc. are sold in dozens and grosses , pharmacists, jewelers, reloaders use the 12 ounce Troy pound as did the British Mint: 1 shillings = 12 pence and 20 shillings = 240 pence or 1 pound sterling. Consider our timing and dating system there are 12 months in the year, and our day is measured in 2 sets of 12 hours. The Babylonians had a 12 hour day. In geometry, a complete circle at 360 degrees is really just subsets of 12, i.e. a 360 degree circle consists of 30 sets of 12. The 12 signs of the zodiac. There were 12 apostles in the bible. You have four fingers with three joints each or a total of 12 joints
Think about the way we name our numbers. We have separate names for 11 Eleven and 12 Twelve then 13 Thirteen. So what happened to 11 -oneteen and 12-twoteen. The Germans did the same 11 - elf and 12 - zwolf while 13-is dreizehn or three and ten. Clearly, it was natural across many cultures to think in terms of dozens.
Now for those of us steeped in decimal calculations base 12 presents some real challenges. Starting with inventing two new digits and naming them. A number of proposals have been put forth such as an upside down 2 and 3. Or A=10 and B=11; X=10 and E=11; T=10 and E=11; or the keyboard friendly *=10 and #=11. Take your pick. As for names DEK, EL, and Doh are gaining in acceptance.
Base 12ers point out that decimal fractions like 1/3 = 0.3333333 repeating in decimal, in base-12 it comes out even at 0.4 but then 1/5 even in decimal at 0.2 in base-12 becomes 0.2497 repeating. So no real gain there.
Multiplication requires some thought 2 X 6 = 10 (1 dozen and zero); 3 X 7 = 19 (1 dozen and 9); or strange to see A X B or T X E or * X # [10 X 11] = 92 (9 dozen and 2).
Kids would probably have no more problems than with decimals but us old farts, that's another story

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## Barrett (May 24, 2019)

Then there was the Imperial Japanese Navy which measured distance and altitude in meters and airspeed in knots!


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## dogsbody (May 24, 2019)

Here in Canada, we have an extra confusion point. There is the original Imperial measurement system that was used up to the late 70's when we went metric, after the US proposed the change, but then they didn't. Then there is the US system that is an off-shoot of the Imperial system but with differences. As our major trading partner, almost everything is marked with both systems: grams/ounces ( but not Imperial ounces ); litres/gallons ( again, not Imperial gallons ).

Ain't life a female dog!


Chris

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## MiTasol (May 24, 2019)

XBe02Drvr said:


> And a met*er* is a mental device used for measuring a linear distance.
> And speaking of the confusion of tools needed to work on today's "global" machinery, I remember maintaining a fleet of Netherlands manufactured Fokker F27s of varying vintages with RR Dart engines made from 1947 to 1977, with Dowty props of varying ages, Lucas electrics, Maxaret antiskid, and Goodyear and Dunlop brake assemblies. SAE and metric tools weren't enough. You had to have British Standard and Whitworth as well. Sometimes you would get an older Dart with newer accessories on it and you'd wind up using Whit, BS, and metric all on the same job. Newer combustion cans on an older engine might have "updated" hardware installed...or not.
> Cheers,
> Wes



My training instructor in 1962 said his job was to teach us the three ways to design and build aircraft.
The RIGHT way,
The WRONG way, and 
The BRITISH way.

The F-27 was a British aircraft assembled in Holland.

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## MiTasol (May 24, 2019)

dogsbody said:


> Here in Canada, we have an extra confusion point. There is the original Imperial measurement system that was used up to the late 70's when we went metric, after the US proposed the change, but then they didn't. Then there is the US system that is an off-shoot of the Imperial system but with differences. As our major trading partner, almost everything is marked with both systems: grams/ounces ( but not Imperial ounces ); litres/gallons ( again, not Imperial gallons ).
> 
> Ain't life a female dog!
> 
> Chris



Politicians and Public Servants (an even bigger contradiction in terms than Military Intelligence) do not give a manure about whether something works in real life.


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## XBe02Drvr (May 25, 2019)

MiTasol said:


> The F-27 was a British aircraft assembled in Holland.


BZZZZT! WRONG!
Designed by Fokker with financial aid from the Netherlands government, built by Fokker, it was British only to the extent of using Dart engines, Dowty props, Lucas electrics, Rootes cabin blowers, and Dunlop wheels and brakes. That was because in postwar Europe, indigenous options were limited and US equipment was overly expensive, not inherently superior, and full of unfamiliar design features and weird dimensions and hardware. The F27 was conceived to be the worldwide DC3 replacement without being "yankee-centric". It actually succeeded rather well despite its higher landing speeds and lack of reverse thrust capability. Way better than its "improved" American cousin, the FH227, of which a third of those manufactured have crashed fatally over the years.
Cheers,
Wes

PS: When our local airline switched from DC3s to FH227s, there was a spate of runway overrun incidents on our downsloping 4800 ft runway, especially in winter. After repeatedly deplaning passengers into a snowbank and hiking them from the end of the runway to the terminal in the cold and snow, then shoveling the airplane out, they started overflying our stop at the slightest excuse. Eventually they more or less got everybody trained to drive 50 miles to the larger airport up the road. We became an EAS airport, and eventually airline service ceased altogether, with my (eventual airline pilot) friend, Kathleen being the final station manager and closing it down.

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## MiTasol (May 25, 2019)

XBe02Drvr said:


> BZZZZT! WRONG!
> Designed by Fokker with financial aid from the Netherlands government, built by Fokker, it was British only to the extent of using Dart engines, Dowty props, Lucas electrics, Rootes cabin blowers, and Dunlop wheels and brakes.



And a lot of other British parts - Dowty landing gears, Redux bonding, Smiths Instruments, British cable tensioners, Brit fuel system components, choke heating, Brit oxgen and plumbing, pneumatics instead of hydraulics, etc, and at some operators even Brit radios. And don't forget the bicycle chains that the Brits love so much.

A not uncommon joke here in Aus was that it was a Brit aircraft and that Fokker only designed and built the box it came in.

The F-28 was also full of Brit stuff but infinitely nicer to work on. It also had a lot of Lockheed features in it. The windscreen attachment and those horrible screws with what looked like a Dzus slot in them (I cannot, and do not want to, remember the proper name for them) were almost perfect copies of L-188 Electra design features to name just two items.

Incidently, according to Donald Douglas the following aircraft were all DC-3 replacements - DC-4, DC-5, DC-6, etc.


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## XBe02Drvr (May 25, 2019)

MiTasol said:


> And a lot of other British parts - Dowty landing gears, Redux bonding, Smiths Instruments, British cable tensioners, Brit fuel system components, choke heating, Brit oxgen and plumbing, pneumatics instead of hydraulics, etc, and at some operators even Brit radios. And don't forget the bicycle chains that the Brits love so much.


I know, I worked with most of that stuff. We had for awhile a very early (1957) one that was still in BEA color scheme and was Brit all the away, even to the COM/NAV radios which we had to rip out because they wouldn't tune the .025 and .075 frequencies. The right engine on that one had a 3 digit serial number with a 1947 manufacture date, a carton full of logbooks, 80,000+ hours of flight time, and 11 different data plates from various Mk numbers that the engine had been modified to over its lifetime. It had been mounted on six different aircraft of five types in that time.
The factory techs that came over to supervise our D checks and the wing bolt service bulletin were very dismissive of American aviation practices in general and our maintenance department in particular. They said that Fokker refused, with good reason, to certify any facilities outside the "civilized world" (Europe and Japan) to do any of the critical work such as wing bolts or D checks, so they did a lot of traveling. According to their leader, a grey haired chap with an ageless face who had been with Fokker since the thirties, when the F27 project began in war-torn Europe, the only options for aircraft appliances were British and American, a no-brainer decision, as British stuff was less expensive, technically superior, and much more familiar worldwide.
Cheers,
Wes


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## Elmas (May 25, 2019)

A Friend of mine made, mid '60s, the last course in piston fighters.
They started the flying school, he told me, with Piaggio's, whose instruments were metric.
Then with T-6, whose instruments were Imperial.
Then with Fiat G-59, whose instrument were metric again
and finally with P-51, whose instruments were Imperial...
Really a mess, He told me, so they painted red stripes everywhere indicating dangerous limits...

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## MiTasol (May 25, 2019)

Just for interest here is the ICAO standard for measurements in aviation - I have not attached the later revision pages.
For Altitude I would say only about 50% of countries comply
Interestingly, on the last page is the ICAO standard for dates. Look in the lower corners of each page and you will see ICAO did not, and still does not, comply with their own ruling.

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## Ole Bill (May 26, 2019)

GrauGeist said:


> We do and we don't - in otherwords, it depends on where measurements are being applied.
> 
> In areas of technical production (military, automotive, etc.), we use metric.
> 
> In home building, food packaging, driving distances and speeds, etc., we use the old system


Personally, I use metric when 'scaling up' drawings when scratch-building balsa flying scale models. It's so MUCH easier doing 'metric math' – than fooling with dividing 1/32 inches Into 1/64 inch measurements. Lazy? No., smart!


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## pbehn (May 26, 2019)

Ole Bill said:


> Personally, I use metric when 'scaling up' drawings when scratch-building balsa flying scale models. It's so MUCH easier doing 'metric math' – than fooling with dividing 1/32 inches Into 1/64 inch measurements. Lazy? No., smart!


Do you model in 1/72 1/48 1/36 1/24?

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## fubar57 (May 26, 2019)

Online Scale Converter Tool - Scale Modelers World


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## mikewint (May 26, 2019)

To many of the major kit makers those scales have become "Goals" rather than Exactitudes and in modernish times have in really become a "Fit-the-Box" scale. That way model manufactures can order a large number of 'standard' sized boxes, saving money, and adjust the kit pieces, just a bit, to fit the box. Modeling magazines have been running articles on this for some time


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## gumbyk (May 26, 2019)

Elmas said:


> A Friend of mine made, mid '60s, the last course in piston fighters.
> They started the flying school, he told me, with Piaggio's, whose instruments were metric.
> Then with T-6, whose instruments were Imperial.
> Then with Fiat G-59, whose instrument were metric again
> ...


It shouldn't be, from a pilot's perspective. All you're looking for is the number on approach. I fly a Tiger Moth in mph, a Nanchang in km/h and any GA aircraft in knots, never had any problem as e.g. approach speed is 60 in the Tiger - 150 in the 'chang.


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## The Basket (May 26, 2019)

Murphys law says that some poor sod is going to get his kph and mph mixed up and find themselves on the wrong side of fate.


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## gumbyk (May 26, 2019)

The Basket said:


> Murphys law says that some poor sod is going to get his kph and mph mixed up and find themselves on the wrong side of fate.


Only if getting out of one aircraft and into another of the same type with different gauges. Different aircraft already have different figures for critical speeds, so the numbers are different anyway. However, if you get out of a 172 with an MPH ASI, and into another 172 with an ASI in knots, that's when problems occur - some things the same, but not everything.


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## Elmas (May 27, 2019)

gumbyk said:


> It shouldn't be, from a pilot's perspective. All you're looking for is the number on approach. I fly a Tiger Moth in mph, a Nanchang in km/h and any GA aircraft in knots, never had any problem as e.g. approach speed is 60 in the Tiger - 150 in the 'chang.



Of course it shouldn't be...
but it was...


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## Barrett (May 30, 2019)

AS I RECALL, the Imperial Navy measured airspeed in knots but altitude and distance in meters (except where meters extended to nautical miles!)
Oh, and IJN kept Tokyo Time world-wide, apparently. But hey, I'm in Arizona where we never go on Daylight, which suits us just find but confused the bejabbers out of everyone sle.

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## Sid327 (Sep 20, 2019)

As a rule of thumb, for mental thinking.

....converting Fahrenheit to Centigrade we always minused 30 and halved it. Good enough for approximation.


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## fubar57 (Sep 20, 2019)

Where I live we use this.....beer will start to freeze at -2°C, time to put on a sweater though I still wear shorts up to -20°ish


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## Sid327 (Sep 20, 2019)

fubar57 said:


> Where I live we use this.....beer will start to freeze at -2°C, time to put on a sweater though I still wear shorts up to -20°ish




You must have Scottish ancestry......

When I lived there, they would have the barbeque out at about 5c and be walking around in shorts, a tee-shirt and with bare feet!


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## MiTasol (Sep 20, 2019)

Sid327 said:


> You must have Scottish ancestry......
> 
> When I lived there, they would have the barbeque out at about 5c and be walking around in shorts, a tee-shirt and with bare feet!



Where I work the lowest recorded temp is 22C and highest is 32C so anything under about 24 is jacket weather. Boring but nice except when the humidity is 90% and above.
Home has a temperature range for 5C to 45C which is not so pleasant and anything below 20 is jacket weather.

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## mikewint (Sep 20, 2019)



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## Sid327 (Sep 20, 2019)

MiTasol said:


> Where I work the lowest recorded temp is 22C and highest is 32C so anything under about 24 is jacket weather. Boring but nice except when the humidity is 90% and above.
> Home has a temperature range for 5C to 45C which is not so pleasant and anything below 20 is jacket weather.



Sounds like a similar workplace I was at before, when it was in the low 20's (centigrade) the locals were freezing their nuts off ....Nigeria.
And, oddly enough home climate is almost the same as yours! (Cyprus)


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## vandee (Sep 20, 2019)

I worked for a shop that made paper machinery. We made widers that wound up at the end
of the paper making machine. We ourselves had 60 inch rolls to test on the WIT WOT machine.
I grew up across the street from a paper mill that made U.S. currency paper. In the late 90s we
were taught metric, I personally was told NOT to convert and shown metric rules and tape measures.
I can use both and to this day use my Starrett metric scale, why? Because I wore out the lines on
my 6 inch pocket scale. John

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## DerAdlerIstGelandet (Sep 20, 2019)

Sid327 said:


> Sounds like a similar workplace I was at before, when it was in the low 20's (centigrade) the locals were freezing their nuts off ....Nigeria.
> And, oddly enough home climate is almost the same as yours! (Cyprus)



Where you flying for Bristow when you were in Nigeria?


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## pbehn (Sep 20, 2019)

Sid327 said:


> Sounds like a similar workplace I was at before, when it was in the low 20's (centigrade) the locals were freezing their nuts off


In the Souks in Saudi Arabia in winter I used to sometimes bump into my co workers from the Phillipines. They were in jackets with fleece lined hats on while I was in my shorts and tee shirt, They were shivering and running to the toilet and considered myself and my mate to be supermen. Human perception of normal temperature can be comical at times.

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## michael rauls (Sep 20, 2019)

fubar57 said:


> Where I live we use this.....beer will start to freeze at -2°C, time to put on a sweater though I still wear shorts up to -20°ish


Ah yes.......the good old beer-ometer

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## Sid327 (Sep 21, 2019)

mikewint said:


> View attachment 553335





DerAdlerIstGelandet said:


> Where you flying for Bristow when you were in Nigeria?



Yes,
for the first time (B212hp)
Then Abu Dhabi Aviation subsequently (AW139)


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## Sid327 (Sep 21, 2019)

pbehn said:


> In the Souks in Saudi Arabia in winter I used to sometimes bump into my co workers from the Phillipines. They were in jackets with fleece lined hats on while I was in my shorts and tee shirt, They were shivering and running to the toilet and considered myself and my mate to be supermen. Human perception of normal temperature can be comical at times.



KSA.
After doing two attachments there, it was enough for me. I would never recommend that place to anybody. Flying over the Red Sea was nice though.


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## The Basket (Sep 21, 2019)

Freedom units v the metric system 😂 

Americans don't want our King but they love an imperial measure

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## Sid327 (Sep 21, 2019)

The Basket said:


> Freedom units v the metric system 😂
> Americans don't want our King but they love an imperial measure



The UK isn't much different. Fuel in litres, distances in miles. Altitude in feet, cubic metres, etc.
But I'm 20 years out of date, we learned both at school way before. Are kids taught only metric now?


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## fubar57 (Sep 21, 2019)

vandee said:


> I worked for a shop that made paper machinery. We made widers that wound up at the end
> of the paper making machine. We ourselves had 60 inch rolls to test on the WIT WOT machine.
> I grew up across the street from a paper mill that made U.S. currency paper. In the late 90s we
> were taught metric, I personally was told NOT to convert and shown metric rules and tape measures.
> ...



I worked in a paper mill for 22yrs, 20 of them running a Voith winder. We measured the width of the paper roll in millimeters and the diameter in inches

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## The Basket (Sep 21, 2019)

Never learnt no inches in school. They had computers at my school, not trebuchets

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## Sid327 (Sep 21, 2019)

fubar57 said:


> I worked in a paper mill for 22yrs, 20 of them running a Voith winder. We measured the width of the paper roll in millimeters and the diameter in inches



The same as car tyres.....

width in mm (then aspect ratio as percentage of the width) and dia in inches.


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## DerAdlerIstGelandet (Sep 21, 2019)

Sid327 said:


> Yes,
> for the first time (B212hp)
> Then Abu Dhabi Aviation subsequently (AW139)



Very cool, I worked in the oil and gas helicopter industry for a while with Era.


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## vandee (Sep 21, 2019)

fubar57 said:


> I worked in a paper mill for 22yrs, 20 of them running a Voith winder. We measured the width of the paper roll in millimeters and the diameter in inches


I made Lenox CSS and HSR sheeters and winders, before that Beloit pulpers and refiners. 22 years in paper
machinery, 3 years wet end, 19 years finishing end. My dad was a "beater engineer" in a paper mill
as was my grandfather. "Smelly" buisiness! LOL. Learned metric at Beloit to compete with Jagenburg. John


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## pbehn (Sep 21, 2019)

fubar57 said:


> I worked in a paper mill for 22yrs, 20 of them running a Voith winder. We measured the width of the paper roll in millimeters and the diameter in inches


Possibly because the width of the roll can be changed and ordered in whatever unit you like, but the diameter is fixed by the machine that makes the roll. Rolls are similar to pipes and almost all pipes are made and ordered in "inches". However this is a nominal pipe size, historically things were done in inches so the dies and formers were in inches and the engineering was in imperial AKA inches. It is nominal because that is just a start point or a convenient "name". You make a large pipe in a former, but the critical dimension is the inside diameter which is obviously the outside minus twice the pipe thickness. Since there is a variance on wall thickness and a variance in sizing control you can order a "40 inch" pipe but the actual dimensions are not 40" and are as easily measured in mm as inches. In the same way almost all pipes are ordered to a minimum maximum length of circa 12.125m this is so they fit in and on 40' trucks and containers. From this most welding set ups have the machines set 12.125m apart which is 40' minus a bit


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## MiTasol (Sep 21, 2019)

The Basket said:


> Freedom units v the metric system 😂
> 
> Americans don't want our King but they love an imperial measure



Metric is easy and makes sense. InFerial is a total shambles and nothing correlates. And the Americans and British have different standards for the same unit just to "help" and maximise confusion.

The reason that the US gallon is different to the Imperial gallon is that when the US decided on the volume for the US gallon Britian had three different gallons in common use. The US chose the most common for the US gallon. Later the British standardised the Imperial gallon and naturally chose a different one to what the yanks chose.

See Numbered drills - wherefrom? - HomemadeTools.net for a summary of just one of the hundreds of InFerial measurement systems (and the source of the word InFerial). Add to that the are also several British wire gauges that are different to all the American wire gauges.

And then of course the brits have dozens of unrelated liquid measures like dramms and gills etc etc.

Barrels are one of my favorite US inferial units. There are seven different barrel sizes used in the USA, with the size being dependent on the contents. Their names and metric equivalents are as follows: US cranberry (95.5 liters), US dry (115.628 liters), US liquid (119.24 liters), US federal (117.348 liters), US federal proof spirits (151.416 liters), US drum (208.4 liters), US petroleum (135 kg.), US petroleum statistical (158.99 liters).
Obviously if one definition of a unit is good, seven must be seven times better.    And of course there are British barrels to add to the confusion.

And the US loves its Tons, long 2240lb, short 2000lb, metric 2204lb (1000kg), shipping 40 cubic feet, deadweight (see below), etc etc.






Below is a simplified chart showing the major InFerial dimesions and their metric replacements.

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## michael rauls (Sep 22, 2019)

That's the simplified version??? I'm usually pretty good at deciphering charts but I can't make heads or tails out of that.


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## michael rauls (Sep 22, 2019)

Ok, I get it now. It's just how many of each unit of measure does it take to constitute the next one indicated by the line/ arrow.
Pretty simple now that I see it.
And 4 poppyseeds to the baleycorn. Of course. Everyone knows that.


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## MiTasol (Sep 22, 2019)

michael rauls said:


> Ok, I get it now. It's just how many of each unit of measure does it take to constitute the next one indicated by the line/ arrow.
> Pretty simple now that I see it.
> And 4 poppyseeds to the baleycorn. Of course. Everyone knows that.



Now tell me without using a calculator

How many Palms to a Gunthers Chain, and
How many inches to a Nautical mile
Metric is just so easy.

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## GrauGeist (Sep 22, 2019)

Let's stop and consider that the British Empire and later, the United States, became world powers using the Imperial system.

So...now about that Metric system...

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## The Basket (Sep 22, 2019)

I grew up in school with metric system so I don't need inches. Never learnt it. 
I remember my father asking for a piece of cheese. I asked how much and he said eighth of an inch. I asked what the hell is that? 

I don't know what big deal is with inches.

One shouldn't have an emotional attachment to a unit of measurement.

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## michael rauls (Sep 22, 2019)

MiTasol said:


> Now tell me without using a calculator
> 
> How many Palms to a Gunthers Chain, and
> How many inches to a Nautical mile
> Metric is just so easy.


Yes metric is much easier and in my opinion better in a practical sense but the twip, pica, and shaftment definitely hold the edge in entertainment value.
And by the way, I always thought a shaftment was the amount of money they take out of your check for taxes.

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## DerAdlerIstGelandet (Sep 22, 2019)

As someone who grew up with both, and regularly used both, Metric is much better and easier to use.

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## N4521U (Sep 22, 2019)

I Hate metric tape measures.
I did grafting for years in the US, inches.
Came to Oz, did draughting, metric, mm's.
But civilians talk metric in Centimeters!!!!!!! WTF.
Then when you use a tape measure, its in Centimeters / Meters.
Why can't it be in continuous measurements, like 90 then 1000, 1100, 1200???????
Instead of 90 then 1 then 10 again, gives me the shits.....
I wanted to order a piece of glass 120 x 350, he wanted hundreds for it!!!!!! *WHAT?????* That's a big piece of glass! *What A2 size?* Oh, you want millimeters!!!!!!
Then long ago I had an American engineer tell me metric was more accurate!!!!! Bwahahaha An inch is an inch, even at 25.4mm.

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## gumbyk (Sep 22, 2019)

N4521U said:


> I Hate metric tape measures.
> I did grafting for years in the US, inches.
> Came to Oz, did draughting, metric, mm's.
> But civilians talk metric in Centimeters!!!!!!! WTF.
> ...


The only people who use centimetres are dressmakers, everything else is millimetres / meters.
Never heard anyone else use cm...


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## Greg Boeser (Sep 22, 2019)

We got some rolls of meter wide steel from Canada once. It was great. I could make a joint of 10x8 without any waste. Or a half joint of 12x8 and a half joint of 8x8.


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## vandee (Sep 22, 2019)

I can saw you a pipe 102 millimeters and be spot on. I can saw you a pipe
at 12 feet 3 and 5/64 of an inch and be spot on. So why is it easier if you
know both methods. Because YOU don't know both? I know both and can do 
both. Neither one is better than the other, it's all in what you use. It's an attitude
that I see is the problem, not the measuring system. JMHO. John

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## gumbyk (Sep 22, 2019)

vandee said:


> I can saw you a pipe 102 millimeters and be spot on. I can saw you a pipe
> at 12 feet 3 and 5/64 of an inch and be spot on. So why is it easier if you
> know both methods. Because YOU don't know both? I know both and can do
> both. Neither one is better than the other, it's all in what you use. It's an attitude
> that I see is the problem, not the measuring system. JMHO. John


I can and do use both, but metric is far easier to do conversions and multiples of.


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## pbehn (Sep 22, 2019)

gumbyk said:


> The only people who use centimetres are dressmakers, everything else is millimetres / meters.
> Never heard anyone else use cm...


Certainly not in UK, they take a very logical system and by switching between mm/cm/ and meters they manage to screw it up, usually by a factor of ten. They do the same in F1 and athletics, speaking in decimals of a second, thousandths then giving the actual number I frequently cant understand what on earth they are talking about.


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## vandee (Sep 22, 2019)

I can do conversions and multiples also. 12 foot 3 inch and 5/64 of an inch is
147.0780". It's just a number and you can do anything you want with a number! John


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## mikewint (Sep 22, 2019)

The only problem some get into with the SI vs Ye Olde Englisher system is the British penchant to take the easy route when doing multiples of a measurement. Grab a piece of string/rope, its length matters not. Without doing any kind/type of measurement there is one point on the string/rope that you can find with perfect exactitude, i.e.: The Middle and the middle of that middle followed by the middle of that middle of that middle of that middle and so on.
That leaves you with the only way to express those halfs of halfs of halfs EVIL FRACTIONS!!!
While dividing something up into 1/10th (not easy to do) to give decimal fractions wherein it is at a glance obvious that 0.375 is less than 0.3906 it is not as obvious that 3/8 and 25/64 are related in the same way. If your 7/16 wrench is a bit too big what size do you try next? Obviously 5/16 is smaller but what about 3/8?
On the other hand if my 9mm wrench does not work it is obvious without thought to try 8mm or 10mm and I know without thought which is larger and smaller
The Non-Relationship of other measuring units like Volume units and Weight/Mass measurement is a separate issue.
Example: Without thought how big a box will hold exactly one gallon of liquid and if that liquid is pure water how much does it weigh?


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## vandee (Sep 22, 2019)

If .4375 is too big obviously .375 is smaller. I'd whip out my Craftsman 3/8 inch open end! John


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## PFVA63 (Sep 22, 2019)

Hi,
As an engineer (naval architect) I'm used to both systems, but when doing my own calculations I will often use the system that I am most familiar with and then convert the results (especially in any spreadsheets that I write).

While I admit that the SI system has some nice features, to me it also has some drawbacks in that its hard for me to visualize some units (specifically pressure/pascals). As such I tend to prefer Imperial units for some calculations but will use SI for some others, and/or a mix for the rest.

Pat


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## MiTasol (Sep 22, 2019)

vandee said:


> I can saw you a pipe 102 millimeters and be spot on. I can saw you a pipe
> at 12 feet 3 and 5/64 of an inch and be spot on. So why is it easier if you
> know both methods. Because YOU don't know both? I know both and can do
> both. Neither one is better than the other, it's all in what you use. It's an attitude
> that I see is the problem, not the measuring system. JMHO. John



I was schooled in both and have spent most of my working life on US aircraft with a few cival Fokkers and Brit military aircraft thrown in but I use metrics and decimals almost exclusively by choice.

When you have to turn down a piece of metal from 1" to 17/64 the first thing you have to do is convert that fraction to a decimal so your micrometer or vernier can measure it. The same for many other restoration processes such as working out the bend allowance for a 3/8 radius flange in a piece of metal and how far apart your rivets are when the drawing calls for 18 rivets in a 14 13/32 run.

Brit aircraft are like their inferial measurements - as my first training instructor put it _the first law of British aircraft design is why make it easy when with a little thought you can make it bloody near impossible_. Lets face it - nobody but the brits make different spanners for the same size bolt. Yes a 3/8 Whitworth spanner will not work on a 3/8 BSF bolt/nut becuase they have different head sizes (and yes I know BSF just uses a different BSW spanner) and unlike metrics it is impossible for the vast majoity of people to instantly calculate the number of inches in 1 mile one chain 1 foot 3 inches. Calculating the metres, cm or mm in 1.87549 km on the other hand can be done in a second by the average ten year old.

I do agree with Mike Wint though that creating fractions based on halves is much easier but outside of that metrics are so much easier because everything is a power of ten and all the measurements are related.


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## swampyankee (Sep 22, 2019)

I've used both inches and metric for computations; the latter are easier.

As for metric vs Imperial: do note even Germany and Russia adopted the metric system even as they defeated the French.


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## pbehn (Sep 22, 2019)

mikewint said:


> The only problem some get into with the SI vs Ye Olde Englisher system is the British penchant to take the easy route when doing multiples of a measurement. Grab a piece of string/rope, its length matters not. Without doing any kind/type of measurement there is one point on the string/rope that you can find with perfect exactitude, i.e.: The Middle and the middle of that middle followed by the middle of that middle of that middle of that middle and so on.
> That leaves you with the only way to express those halfs of halfs of halfs EVIL FRACTIONS!!!
> While dividing something up into 1/10th (not easy to do) to give decimal fractions wherein it is at a glance obvious that 0.375 is less than 0.3906 it is not as obvious that 3/8 and 25/64 are related in the same way. If your 7/16 wrench is a bit too big what size do you try next? Obviously 5/16 is smaller but what about 3/8?
> On the other hand if my 9mm wrench does not work it is obvious without thought to try 8mm or 10mm and I know without thought which is larger and smaller
> ...


The goal on a football (soccer) pitch is 8 yards by 8 feet. What would a metric goal be? Same for most sports.


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## mikewint (Sep 22, 2019)

9.75 meters


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## wuzak (Sep 22, 2019)

swampyankee said:


> I've used both inches and metric for computations; the latter are easier.
> 
> As for metric vs Imperial: do note even Germany and Russia adopted the metric system even as they defeated the French.



When did they do that?

As far as I can tell, the Germans were using metric prior to WW2.


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## tyrodtom (Sep 22, 2019)

wuzak said:


> When did they do that?
> 
> As far as I can tell, the Germans were using metric prior to WW2.



Germany went metric in the 1870s, he's probably referring to the Franco-Prussian war.

Speaking on our own education system and measurements, I've had a new mechanic trainee that had to ask which was bigger, 7/8 or 15/16 ?

He didn't appear to have a problem with metric sizes.


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## gumbyk (Sep 22, 2019)

PFVA63 said:


> While I admit that the SI system has some nice features, to me it also has some drawbacks in that its hard for me to visualize some units (specifically pressure/pascals). As such I tend to prefer Imperial units for some calculations but will use SI for some others, and/or a mix for the rest.


That's not a drawback of the metric system, but just your perception of it.


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## N4521U (Sep 22, 2019)

My calipers don't care, just a push of a button.
My wife talks CM, I talk mm....... conflict!!!!!!!
Now, spanners, WhatThe, it's and END wrench!!!!!
Not a jig saw, Sabre Saw!!!!!!!


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## DerAdlerIstGelandet (Sep 22, 2019)

V
 vandee


If you are going to disagree with so many people, then why don't you counter with something as to why?


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## wuzak (Sep 23, 2019)

PFVA63 said:


> While I admit that the SI system has some nice features, to me it also has some drawbacks in that its hard for me to visualize some units (specifically pressure/pascals). As such I tend to prefer Imperial units for some calculations but will use SI for some others, and/or a mix for the rest.



I'd suggest that is from experience and familiarity.


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## The Basket (Sep 23, 2019)

Imperial Russia kept there own measures which is why early Mosin sights are in arshins. It was the ussr which converted to metric.

The issue is not individual use of measures but international or even workshop use. Getting the two mixed up can create havoc and some projects have failed when the two have mixed up.


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## swampyankee (Sep 23, 2019)

For the Germans, during unification, before which every nanostate had its own units.

The French left a lot in their wake, even after the defeat of the Napoleonic wars.


The Basket said:


> Imperial Russia kept there own measures which is why early Mosin sights are in arshins. It was the ussr which converted to metric.
> 
> The issue is not individual use of measures but international or even workshop use. Getting the two mixed up can create havoc and some projects have failed when the two have mixed up.



That last is very true. See, for example Mars Climate Orbiter Failure Board Releases Report


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## GrauGeist (Sep 23, 2019)

As a mechanic, I've found that metric hardware is a pain in the ass unlike USS/SAE sizes.

On the otherhand, metric wrenches work on SAE hardware well enough, like when the 3/8 wrench is missing (as usual), the 10mm wrench will do - unless that bastard is missing too...

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## XBe02Drvr (Sep 23, 2019)

GrauGeist said:


> As a mechanic, I've found that metric hardware is a pain in the ass unlike USS/SAE sizes.


I agree, but only for us "metric immigrant" dinosaurs. The "metric native" types don't seem to have that kind of problem.
The airline shop I worked in had two guys who, though Americans, had grown up overseas, and they seemed to flow smoothly between metric, SAE, Whitworth, and British Standard with nary a cuss word heard. And aging Dart engines on a Dutch airframe along with Lucas and Dowty accessories could present some dimensional challenges.
Cheers,
Wes


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## MiTasol (Sep 23, 2019)

XBe02Drvr said:


> aging Dart engines on a Dutch airframe along with Lucas and Dowty accessories could present some dimensional challenges.
> Cheers,
> Wes



Amen to that


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## PFVA63 (Sep 23, 2019)

Wuzak & Gumbyk,

I hear what your saying about being an issue with familiarity, and it makes sense. But for me I guess its maybe that since a lot of Imperial units are based on being close to normal everyday, easily accessible things* it make it easier for me to grasp not only those units but also units derived from them - like pressure in terms of psi or psf.

In the SI system it's not quite so easy for me to visualize some items, especially in terms of pressure, especially when you realize that a Newton is roughly the same weight as a typical apple. As such when you start talking about pressures of typical things like oil pressure, air pressure and steel or aluminum material properties you end up having to put those values in terms of kilo- or even Mega-Newtons/square meter (or kilo- and Mega-Pascals)

Pat

* Specifically, although units like a inch, foot and yard are notionally based on the length of a hand foot and arm of some "King" in olden times, my foot arm and hand are probably close enough to those values for making quick estimates.


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## DerAdlerIstGelandet (Sep 23, 2019)

XBe02Drvr said:


> I agree, but only for us "metric immigrant" dinosaurs. The "metric native" types don't seem to have that kind of problem.
> The airline shop I worked in had two guys who, though Americans, had grown up overseas, and they seemed to flow smoothly between metric, SAE, Whitworth, and British Standard with nary a cuss word heard. And aging Dart engines on a Dutch airframe along with Lucas and Dowty accessories could present some dimensional challenges.
> Cheers,
> Wes



That is because Metric is easy.

If you can count, you can do metric.

1, 2, 3...

0.1, 0.2, 0.3...

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## DerAdlerIstGelandet (Sep 23, 2019)

My wife used to teach at a college here in the US. She is from Germany, and was appalled that she had to waste the first week of class teaching kids who are supposed to be ready for college how the metric system works. It’s counting numbers, and knowing how many units make up another specific unit.

There is nothing difficult about it...

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## gumbyk (Sep 23, 2019)

DerAdlerIstGelandet said:


> My wife used to teach at a college here in the US. She is from Germany, and was appalled that she had to waste the first week of class teaching kids who are supposed to be ready for college how the metric system works. It’s counting numbers, and knowing how many units make up another specific unit.
> 
> There is nothing difficult about it...


My 7 year-old gets it... and works in inches and feet as well as metric (much to his teacher's )


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## mikewint (Sep 23, 2019)

Not to mention that it is all done exactly the way we count, by 10s and rather than having separate names for every unit that really tell you nothing about the measurement, like: TUN. What is it?, How big is it?, What does it measure?
The Latin prefixes are in common language: DECI- (Decade, Dime,etc.) CENTI- (Century) and MILLI- (Millennium, Million)
The Greek ones are perhaps a bit unusual DEKA- HECTO- because of computers the larger like KILO-, MEGA-, GIGA- AND TERA- are probably familiar even if they don't know exactly what number to assign each.
In the other direction MICRO- is certainly familiar (that's why they call it a MICROscope), NANO- is also perhaps familiar from science fiction NANObots or NANites, and PICO- proibly not well known.
So when I see the word CENTI-METER I know that it is 1/100 of the base unit METER a measurement of length. KILO-LITER is 1000 of the base unit LITER a measure of volume. MICRO-GRAM is 1/1,000,000 of the base unit GRAM a measure of mass.
Beats me how it could be any simpler

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## gumbyk (Sep 23, 2019)

mikewint said:


> and MILLI- (Millennium, Million)



milli is 1/1000, nothing to do with million...


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## pbehn (Sep 23, 2019)

The UK has experimented with metric politicians, the first version Ed Miliband wasn't great but better than Michael Foot, its early days.

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## mikewint (Sep 23, 2019)

Was not referring to the actual metric measurement only that the prefix Latin MILLI- was in common language usage meaning 1000. A MILLION is called a million because it is one thousand 1,000s as a Millennium is 1000 years
The Latin Prefixes move the decimal point to the right making the measurement smaller by the prefix amount


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## gumbyk (Sep 23, 2019)

mikewint said:


> Was not referring to the actual metric measurement only that the prefix Latin MILLI- was in common language usage meaning 1000. A MILLION is called a million because it is one thousand 1,000s as a Millennium is 1000 years
> The Latin Prefixes move the decimal point to the right making the measurement smaller by the prefix amount


milli is one_ thousandth_ in decimal units, mille is the latin root that it comes from, and means one thousand, kilo is the decimal prefix for thousand. That's how some people find it confusing, there's six orders of magnitude difference between milli and mille.


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## MiTasol (Sep 24, 2019)

mikewint said:


> Not to mention that it is all done exactly the way we count, by 10s and rather than having separate names for every unit that really tell you nothing about the measurement, like: TUN. What is it?, How big is it?, What does it measure?



Damn - forgot that one in post #122 when I covered the other tons

From memory it is a volume of wine but I cannot remember how much.

Checking on giggle it is
*Definition of tun*
1 *: *a large cask especially for wine 
2*: *any of various units of liquid capacity especially one equal to 252 gallons 
*Synonyms for tun*
Synonyms barrel, butt, cask, firkin, hogshead, keg, kilderkin, pipe, puncheon, rundlet (or runlet)
*Examples of tun in a Sentence*
in olden days an English ship's capacity was measured by the number of _tuns_ of wine it could hold 

*I guess your question has opened a ton/tun of other contradictions in InFerial measurements and the question : is that 252 Imp or 252 US gallons.*

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## mikewint (Sep 24, 2019)

gumbyk said:


> there's six orders of magnitude difference between milli and mille.


We're still talking at cross-purposes. Read carefully my post and the my previous posting.
When the historic Metric system was being developed it was decided to use BOTH Greek and Roman numbers as prefixes since, at the time, any educated person spoke one or both.
The Latin numbers Decem, Centum, and Milia for 10, 100, and 1000 were chosen to represent the smaller divisions of the base length measurement METER. So when the meter was broken up into *TEN* smaller pieces *EACH* smaller piece (of which there were *TEN*) was called a DECI-meter and each one was indeed 1/10 of the whole METER. In a similar manner EACH Decimeter piece was broken up into ten pieces making 10 x 10 = *100 total pieces.* Since there are now *ONE HUNDRED* *total* pieces *EACH *piece was called a CENTI-meter and each one was, of course, 1/100 of the total meter. The last historic step was to break each centimeter piece into ten equal pieces giving 10 x 10 x10 = *1000 total pieces.* As before since there are now *ONE THOUSAND total* pieces *EACH *pieces was called a MILLI-meter and each one was, of course, *1/1000 of the total meter*

In the opposite direction the Greek numbers DEKA, EKATO, and CHILLOI were used to represent MULTIPLES of the base meter. The spellings have been Anglicized in the intervening years to our modern spellings DECA, HECTO, and KILO. So TEN meters laid end to end become a single DECA-meter and ten Dekameters laid end to end (making 100 total meters) becomes a single HECTO-meter and lastly 10 hectometers (making 1000 total meters) laid end to end become a single KILO-meter.

As science developed the need to measure things a LOT bigger than KILO and a LOT smaller than MILLI- soon became necessary. Steps of ten were insufficient thus below (smaller than) MILLI- the steps became THREE powers of TEN rather than ONE power
So a single MILLI-meter was broken up into 1000 equal pieces and each piece became, from the Greek word MIKROS (small), a single MICRO-meter. The abbreviation also required that the Greek letter MU ( *μ *) be used since all English M (mega) and m (milli) were already in use. Exceptions were made because not all font sets had the Greek letter Mu in them thus MC is also an acceptable abbreviation. Medically you will often see *mcg* which is a MICRO-gram. 
Each Micrometer is then broken up into 1000 equal pieces. Each piece becomes a NANO-meter from the Greek Nanus (dwarf)
Each Nanometer is then broken up into 1000 equal pieces. Each piece becomes a PICO-meter. Here the Metric Guys switched to the Spanish word PICO meaning BIT (also PEAK and weirdly BEAK as in PICO DE GALLO [Beak of Rooster]). Each of these pieces is then a PICO-meter.

Back to the top end, each one becoming 1000 times larger than the previous we have:
1000 Kilometers laid end to end becoming a single MEGA-meter from the Greek MEGAS (Great)
1000 Megameters laid end to end becoming a single GIGA-meter from the Greek GIGAS (Giant)
1000 Gigameters laid end to end becoming a single TERA-meter from the Greek TERAS (Monster)


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## mikewint (Sep 24, 2019)

PFVA63 said:


> In the SI system it's not quite so easy for me to visualize some items, especially in terms of pressure, especially when you realize that a Newton is roughly the same weight as a typical apple. As such when you start talking about pressures of typical things like oil pressure, air pressure and steel or aluminum material properties you end up having to put those values in terms of kilo- or even Mega-Newtons/square meter (or kilo- and Mega-Pascals)


Here I would totally agree with you. SI has both improved the old Metric and in some cases made it more difficult in the man-sized world of measurement.
BUT, you needs must understand the WHY and Necessity of those changes.
The intent was a rational simplified system for all times and all peoples based on natural standards. The use of numeric prefixes attached to the base measurement so that anyone would know just by looking at the word for the measurement just how much and of what. If you belonged to the Correct Guild you knew exactly what a TOD was and what it measured.
[Do you know why Teachers used to ask students "Which weighs more a POUND of GOLD or a POUND of FEATHERS"] (It's feathers by quite a bit)
The original INTENT of the Metric system soon became lost as Science developed and more and more things besides length, volume, and mass needed to be measured. So units like FARAD, ERG, HENRY, DYNE, SIEMENS, STHENE, WEBER, BARYE, TESLA, PIEZE, MAXWELL, LUMEN, GAUSS, LUX, OERSTEN, STOKES, POISE, and ANGSTROM became metric units. So as earlier IF you belonged to the proper group you knew exactly what and how much.
Thus it was time to end the mess and clean house. In 1960 the SI system was adopted and SEVEN base units { second, metre, kilogram, ampere, kelvin, mole, candela } were accepted and defined. After that point anything else that needed to be measured would have to come from combinations of those base units.

So when we come to measure pressure which is FORCE per unit of AREA. We are forced to use just those seven base units. Thus FORCE becomes the NEWTON [One newton is the force needed to accelerate one kilogram of mass at the rate of one meter per second squared in the direction of the applied force or 1 kg⋅m⋅s−2] and area must be meters squared. 
Thus PASCAL is then (in terms of base units ): One pascal is one kilogram per meter per second squared; that is, 1 Pa = 1 kg · m-1 · s-2. As you observed a very tiny amount of pressure, in US customary units 1.450 X 10^-4 PSI or 0.0001450 psi.
A better mental picture might be this: A newton of weight is about 1/4 Pound so imagine a Soda Cracker 3.25 feet by 3.25 feet. Spread evenly over the entire cracker 1/4 pound stick of butter. The butter exerts a pressure of ONE PASCAL on the cracker

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## soulezoo (Sep 24, 2019)

This makes my head hurt...

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## mikewint (Sep 24, 2019)

Its become even simpler and more universal now that there are no longer actual physical standards maintained. 
In November 2018, the world’s measurement experts voted and unanimously approved a revision of the SI that establishes a measurement system entirely based on physical constants of nature. The changes became effective on World Metrology Day, May 20, 2019.

Unit of length meter The meter, symbol m, is the SI unit of length. It is defined by taking the fixed numerical value of the speed of light in vacuum c to be 299 792 458 when expressed in the unit m s-1, where the second is defined in terms of ΔνCs.

Unit of mass kilogram The kilogram, symbol kg, is the SI unit of mass. It is defined by taking the fixed numerical value of the Planck constant h to be 6.626 070 15 × 10-34 when expressed in the unit J s, which is equal to kg m2 s-1, where the meter and the second are defined in terms of c and ΔνCs.

Unit of time second The second, symbol s, is the SI unit of time. It is defined by taking the fixed numerical value of the cesium frequency ΔνCs, the unperturbed ground-state hyperfine transition frequency of the cesium 133 atom, to be 9 192 631 770 when expressed in the unit Hz, which is equal to s-1.

Unit of electric current ampere The ampere, symbol A, is the SI unit of electric current. It is defined by taking the fixed numerical value of the elementary charge e to be 1.602 176 634 x 10-19 when expressed in the unit C, which is equal to A s, where the second is defined in terms of ΔνCs.

Unit of thermodynamic temperature kelvin The kelvin, symbol K, is the SI unit of thermodynamic temperature. It is defined by taking the fixed numerical value of the Boltzmann constant k to be 1.380 649 x 10-23 when expressed in the unit J K-1, which is equal to kg m2 s-2 K-1, where the kilogram, meter and second are defined in terms of h, c and ΔνCs.

Unit of amount of substance mole The mole, symbol mol, is the SI unit of amount of substance. One mole contains exactly 6.022 140 76 x 1023 elementary entities. This number is the fixed numerical value of the Avogadro constant, NA, when expressed in the unit mol-1 and is called the Avogadro number. The amount of substance, symbol n, of a system is a measure of the number of specified elementary entities. An elementary entity may be an atom, a molecule, an ion, an electron, any other particle or specified group of particles.

Unit of luminous intensity candela The candela, symbol cd, is the SI unit of luminous intensity in a given direction. It is defined by taking the fixed numerical value of the luminous efficacy of monochromatic radiation of frequency 540 x 1012 Hz, Kcd, to be 683 when expressed in the unit lm W-1, which is equal to cd sr W-1, or cd sr kg-1 m-2 s3, where the kilogram, meter and second are defined in terms of h, c and ΔνCs.


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## wuzak (Sep 24, 2019)

mikewint said:


> "Which weighs more a POUND of GOLD or a POUND of FEATHERS"] (It's feathers by quite a bit)



You may want to explain that one.


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## wuzak (Sep 24, 2019)

Imperial units are now all defined in terms of metric units.

That is, the inch doe snot have its own standard measure, but is defined as 0.0254 metres. 1 pound is 0.453592 kilograms.


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## XBe02Drvr (Sep 24, 2019)

mikewint said:


> In November 2018, the world’s measurement experts voted and unanimously approved a revision of the SI that establishes a measurement system entirely based on physical constants of nature.


Hey, who's got my Tylenol?

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## michael rauls (Sep 24, 2019)

wuzak said:


> You may want to explain that one.


I think he was trying to say they weigh the same regardless of which takes up more space but it does make for head scratcher of a sentence


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## fubar57 (Sep 24, 2019)

Copy/paste probably went haywire

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## michael rauls (Sep 24, 2019)

fubar57 said:


> Copy/paste probably went haywire


.........


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## pbehn (Sep 25, 2019)

Gold used to be measured in Troy ounces and pounds.

*Troy pound*

The troy pound is 5 760 grains (≈ 373.24 g, 12 oz t), while an avoirdupois pound is approximately 21.53% heavier at 7 000 grains (≈ 453.59 g).


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## Elmas (Sep 25, 2019)

Land Surveyors nowadays (well, my Father had his first centesimal theodolite early '60s...) divide a full circle not in 360° but in 400c, and 1c is divided in 100 parts (and not 60..) and so on. Much easier to use calculators when adding or subtracting angles.



gumbyk said:


> The only people who use centimetres are dressmakers, everything else is millimetres / meters.
> Never heard anyone else use cm...



It depends from the precision requested by the job.
For example a bricklayer here in Italy will use cm, even if cm it is not an SI unit, as the precision requested by his job is generally, at the best, +/- 0,5 cm (at the very best...), and he will laugh like mad if you will give him a drawing with dimensions indicated in mm, while if you indicate dimensions in meters you always will have that damned comma in the way. Bricklayers will always translate m in cm, and the possibility of an error arises.

In his memories Kelly Johnson laughing remembers of an episode when, early in his career, he was charged of the design of some masonry job, and with his astonishment found the bricklayers surrounded by a cloud of dust, as they were trying to achieve the precision indicated in the drawings that was that of an aeronautical standard.
American bricklayers were probably very polite, as here in Italy they should have greeted the designer with that in Italian is called a"pernacchia", behind his shoulders, of course.
To the contrary, a drawing addessed to a blacksmith must have dimensions indicated in mm, as the precision needed is +/ 0,5 mm otherwise bolts won't go though holes.

So, indicating in a drawing that a dimension is 3,23 m or 323 cm generally involves that a precision of +/- 0,5 cm is accepted, while if you indicate a dimension of 3230 mm the precision achieved in the finished product must be +/- 0,5 mm and an indication of 3230,0 mm so on...

The problem is that SI was imposed by Physics, with their Pascals and all that silly units, and not by Engineers. We were working so wonderfully with our own System (m and Kgf, as fundamental units).


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## wuzak (Sep 25, 2019)

So it was a trick question?


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## XBe02Drvr (Sep 25, 2019)

wuzak said:


> So it was a trick question?


....that backfired!


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## mikewint (Sep 25, 2019)

wuzak said:


> So it was a trick question?


No not exactly a "trick" ,as such, but a way for teachers, at the time, to point out to students that the measurement POUND was of two types as Pbehn pointed out in his post above. The Troy (after Troyes, France a commercial trading center for precious things) System of weights and measures was much more strictly enforced and accurate than the English System. So valuable things and things that had to be accurately measured employed the TROY system. Remnants of the system are still in use today: CARETS for diamond weights; GRAINS for drugs and gun powder; and Ye Olde English DRAM shops.
Consider old British money. ONE POUND = 20 SHILLINGS and ONE SHILLING = 12 PENSE so there were 240 PENSE in ONE ENGLISH POUND
Now consider the TROY system. ONE TROY POUND = 12 TROY OUNCES and ONE TROY OUNCE = 20 PENNYWEIGHTS so that means that ONE TROY POUND = 240 PENNYWEIGHTS
As another aside take the measurement MILE, simple and easy right. Well again as with all things English not quite so JUST in the UK alone there were four different MILES in use and many more if you include the continent. Even today there are eight different MILES in usage


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## gumbyk (Sep 25, 2019)

Elmas said:


> It depends from the precision requested by the job.
> For example a bricklayer here in Italy will use cm, even if cm it is not an SI unit, as the precision requested by his job is generally, at the best, +/- 0,5 cm (at the very best...), and he will laugh like mad if you will give him a drawing with dimensions indicated in mm, while if you indicate dimensions in meters you always will have that damned comma in the way. Bricklayers will always translate m in cm, and the possibility of an error arises.



My bricklayer father never did...


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## mikewint (Sep 25, 2019)

Elmas said:


> if you indicate a dimension of 3230 mm the precision achieved in the finished product must be +/- 0,5 mm and an indication of 3230,0 mm so on...


Things may be different in the trades but IF the measurement is TRULY listed as 3230 mm then the terminal zero is NOT SIGNIFICANT. It is present only as a place-holder to move the left-most 3 into the tens column. That makes the leftmost 3 an UNCERTAIN digit. The ruler used to make that measurement had a RESOLUTION of 100 mm (had actual marks every 100 mm) There were no marks on the ruler for Tens or Ones. Thus when the measurement was made the actual object ended between the 3300 and 3200 marks. I estimated that the amount above the 3200 mark was about 30 so I wrote 3200 + 30 = 3230 mm and the error would be half the uncertain digit or +/- 5 mm. So the object is somewhere between 3235 and 3225 mm.
If you want that terminal zero to be significant then place a decimal point after it or a bar over it. So listing the measurement as 3230. or 3230, is a more accurate measurement. This ruler had marks for thousand - hundreds - and tens but no ones marks so I estimated that the ones reading was 0 with an error of +/- 0.5mm 
Now I certainly can specify in my plans a length of 3230 mm with a stated non-standard error of +/-0.5 but it has to be stated. Stating the error means than you can call for any precision you want 3230 mm +/- 0.2mm for example


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## pbehn (Sep 25, 2019)

mikewint said:


> Things may be different in the trades but IF the measurement is TRULY listed as 3230 mm then the terminal zero is NOT SIGNIFICANT. It is present only as a place-holder to move the left-most 3 into the tens column. That makes the leftmost 3 an UNCERTAIN digit. The ruler used to make that measurement had a RESOLUTION of 100 mm (had actual marks every 100 mm) There were no marks on the ruler for Tens or Ones. Thus when the measurement was made the actual object ended between the 3300 and 3200 marks. I estimated that the amount above the 3200 mark was about 30 so I wrote 3200 + 30 = 3230 mm and the error would be half the uncertain digit or +/- 5 mm. So the object is somewhere between 3235 and 3225 mm.
> If you want that terminal zero to be significant then place a decimal point after it or a bar over it. So listing the measurement as 3230. or 3230, is a more accurate measurement. This ruler had marks for thousand - hundreds - and tens but no ones marks so I estimated that the ones reading was 0 with an error of +/- 0.5mm
> Now I certainly can specify in my plans a length of 3230 mm with a stated non-standard error of +/-0.5 but it has to be stated. Stating the error means than you can call for any precision you want 3230 mm +/- 0.2mm for example


Why do you have such a special talent for turning a light hearted discussion into an oppressive bore? You are wrong because you are stating what you understand as the conventions you know in your world, other people know other conventions in theirs. In all cases the defining authority is the buyer and I have been involved in very heated and serious discussions between people buying and selling in specifications which were in decimal notation while the laboratory charged with testing only quoted values in PPM. Whatever your opinion is, specifications agreed by buyer and seller decide what is what, you are merely discussing your version of the defaults.

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## ThomasP (Sep 26, 2019)

This discussion is one of the types that, for me, makes participating in this forum enjoyable. Full of differing views, sometimes odd and esoteric information, useful information, and humor. Thank you all.

Possibly you will find the following interesting. It is my take on what occurred during my career as an engineer/fabricator.

In early- to mid-1970s high school (grades 7-12 in my neighborhood) I learned of something strange (to some of the teachers) and wondrous (to some of the other teachers) called the metric system. Basically, the shop (metal and wood) teachers thought "WTF", while the science (chemistry, physics, biology) teachers thought "yay!, we are moving into the future!".

At university (my majors were mechanical engineering and physics) and vocational-trade school (training for machining and other forms of fabricating) in the late-70s, these views were further expanded upon.

The engineering teachers had the attitude of "this would be a good idea if it offered any significant improvement in the ability to design and produce something, since it does neither...WTF".

The vocational-trade school teachers said "WTF, since every piece of equipment we have here is graduated/marked in English Standard, and since we are unlikely to receive any funding to replace/convert the WWII era surplus machines we have, WTF again".

The Physics and other science teachers said "yay!, we are moving into the future, really slowly, but moving we are".

Once I was in the working environment the views became somewhat more diverse as time passed. At my first real job in my chosen professions (at the Chrysler tank plant in Lima, Ohio) I was assigned to the alternate diesel power plant project for the M1 Abrams, then (at a low level) in various aspects of the pre-production design modification and trials, after which I was then transferred to various manufacturing aspects of the production turret weldments and assemblies.

At Chrysler the majority view of the engineers (via the executive types) was "it has become necessary that we can still design and manufacture items using English Standard, but dimension/tolerance them in both the English and Metric system, so that our allies across the pond can take part in a shared production environment."

The fabrication personal thought "WTF, the Europeans must be too inept to convert inches to mm".

After leaving Teledyne and Chrysler (in 1983) I bounced around from company to company for the next 30 years or so, sometimes working as an engineer and sometimes as a fabricator (usually a machinist) and was exposed to continuing changes in attitude.

As an engineer it could be summed up as "our economy is so entwined with the rest of the world's industrialized nations that we need to get with the times...oh well".

As a machinist (aside from when manufacturing military items) I did not start to run into any perceptible acceptance of the Metric system in general manufacturing until the mid-1990s, when the international trade system began to effect the US economy more, and more of the parts being produced in the US were to be sold in the Europe. The basic attitude was "well hey, WTF, if we are going to make money we need to get with the times... slowly. But why can't we make the other industrialized nations use the English system?".

When I took continuing education classes at university and vocational/trade school, the university science teachers had the attitude of "yay, we can pat ourselves on the back, the sciences at least have joined the modern era!".

The vocational/trade school teachers (who had become part of the university system during the early- to mid-1990s) said "it is a great idea (not really, but we are willing to try). When are we going to be given funds to replace the WWII surplus manual lathes, knee mills, horizontal mills, surface grinders, cylindrical grinders, centerless grinders, tool grinders, jig grinders, jig borers, and the newer (but out-dated) CNC knee mills, CNC lathes, CNC machining centers, CNC turning centers,....etc that are all graduated in inches?". (In 1993-94 I taught substitute and part time in the machining department of a Technical College (aka vocational/trade school). While I was there, we were able to procure a new (new-out-of-the-box) 1947 LeBlond lathe.)

In the late-1990s to early-2000s I worked in several small to medium machine job shops (ie they did not specialize in any particular type of machining, being able to do prototyping, short-run production, and long-run production). 99% of the blueprints we received were dimensioned in inches, with about 30% or so using Geometric Tolerancing. Nearly all of of the medical industry specific blue prints had been converted from Metric to English dimensions specifically for the use of the machine shops.

Also in the early-2000s, I worked several contract engineering jobs in what might be considered specialized areas. One of them involved a large medical device company. They had recently had major problems with quality control in some of their products. My job was specific to teaching continuing education (ie remedial) classes in English-to-Metric/Metric-to-English blueprint conversion, engineering application tolerancing, Geometric Tolerancing, and SPC (Statistical Process Control) and TQM (Total Quality Management) in particular where the applications involved manufacturing and inspection of English-to-Metric/Metric-to-English requirements and Geometric Tolerancing.

The attitude of the engineers was good natured tolerance for the most part, except for the ones who were responsible for the problems...they exhibited resentment.

The attitude of the people in manufacturing and quality control departments was a willingness to learn and most were somewhat enthusiastic...except for the higher level supervisors...they exhibited resentment.

sigh

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## Elmas (Sep 26, 2019)

pbehn said:


> Why do you have such a special talent for turning a light hearted discussion into an oppressive bore? You are wrong because you are stating what you understand as the conventions you know in your world, other people know other conventions in theirs. In all cases the defining authority is the buyer and I have been involved in very heated and serious discussions between people buying and selling in specifications which were in decimal notation while the laboratory charged with testing only quoted values in PPM. Whatever your opinion is, specifications agreed by buyer and seller decide what is what, you are merely discussing your version of the defaults.



Exactly. Some people I knew had a quarry extracting granite slabs and accepted a contract with some Australian contractors for a skyscraper but, rather lightly, they did not notice (or didn't care) that in the contract a tolerance of +/- 0 mm was stated for the thickness of the slabs. This was clearly a swindle. They had a hell of a trouble to be payed by the buyer ( and don't know if they have been payed indeed).

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## Elmas (Sep 26, 2019)

I made these drawings very, very early in my career (pre 1980). No computers then! Everything had to be made by pencil, squares and ruler. I bought the first computer able to draw and the firts plotter (an HP_* pen*_ plotter) in 1983.

Sorry for the poor photos of the prints.
A steel truss, where dimensions are in mm: in a few cases, when calculations suggested it, an indication of 0,5 mm in the dimension was made







And a concrete bridge where dimension are or in meters or in cm, as that is the precision that it is possible to get with that material




As far as I know these structures are still there, if Lybians did not blast them..

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## Elmas (Sep 26, 2019)

I'd like to tell you some facts about the design of these towers, in which I was involved in the same years ( early '80s) together with a Canadian structural engineering firm, but unfortunately I've not the time now...


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## mikewint (Sep 26, 2019)

The goal of SI is to eliminate all of these various regional conventions and ways of doing things and adopt universal standards. I was never in the practical construction or engineering end of things so from the scientific end of the scale, it was always YEA METRIC. When SI took control in 1960 it was a lower case "yea" mostly because of the elimination of units not derived from the seven base units and the adoption of derived units like Pascals which, IMHO, are impractical in the man-sized world. Gone were all those nice pratical units like Angstroms, mm of Hg, Gauss, Lumens, etc.
The other changes that I noted and which I still see here on the forum is the use of Commas for Decimal Points. Seeing things like 0,05 mm is very strange to me and is one of the things addressed by SI. Here in the States we always used Periods for Decimal Points so I grew up with 0.05 mm while Europeans were doing 0,05 mm. Again in the States we did use Commas but only to separate groups of zeros into threes so: 1,000,000,000. SI addressed this by eliminating the comma decimal point and the commas between groups of three zeros. So in SI America got 0.05 but lost the commas in large numbers so we are now supposed to write 1000 000 000 and even after the decimal 0.000 000 000 05 we're supposed to group into threes.
Uncertainty in measurement was an easy topic in Ye Olde Days of Yore because Slide Rules only allowed 3 digits at most on most scales. Once electronic calculators came into play it became very difficult to convince students that eight or more of those digits in your calculation are meaningless garbage being simply error times error times error divided by error. So learning that 3230 mm; 3230. mm; 3230.0 mm; and 3230.00 mm are all radically different measurements made with radically different measuring "sticks" with a built-in Standard Error is a difficult concept for some to grasp. Significant Figures and Uncertainty in measurement and its effect on calculation takes lots of time. 
Then Heisenberg's Uncertainty Principle raises its ugly little head and it all goes to Gehenna in a hand-basket.


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## Macandy (Sep 26, 2019)

“......We built Apollo using inches and put a man on the Moon.
They built the Space Shuttle with the metric system and it blew up...”


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## gumbyk (Sep 26, 2019)

Macandy said:


> “......We built Apollo using inches and put a man on the Moon.
> They built the Space Shuttle with the metric system and it blew up...”


One Apollo lost in a fire, one very nearly lost, out of 17.
2 Shuttle missions lost out of 135. (And I'm fairly certain that the o-ring that failed to cause the Challenger accident was imperial)

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## fubar57 (Sep 26, 2019)

“......We built Apollo using inches and put a man on the Moon.
They built the Space Shuttle with the metric system and it blew up...” 



.....and Apollo 13?


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## DerAdlerIstGelandet (Sep 26, 2019)

Macandy said:


> “......We built Apollo using inches and put a man on the Moon.
> They built the Space Shuttle with the metric system and it blew up...”

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## davparlr (Sep 26, 2019)

Mars Climate Orbiter - Wikipedia
.....due to ground-based computer software which produced output in non-SI units of pound-force seconds (lbf·s) instead of the SI units of newton-seconds (N·s)....

You would think rocket scientist would ......


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## pbehn (Sep 26, 2019)

mikewint said:


> Uncertainty in measurement was an easy topic in Ye Olde Days of Yore because Slide Rules only allowed 3 digits at most on most scales. Once electronic calculators came into play it became very difficult to convince students that eight or more of those digits in your calculation are meaningless garbage being simply error times error times error divided by error. So learning that 3230 mm; 3230. mm; 3230.0 mm; and 3230.00 mm are all radically different measurements made with radically different measuring "sticks" with a built-in Standard Error is a difficult concept for some to grasp. Significant Figures and Uncertainty in measurement and its effect on calculation takes lots of time.
> .


This is true but just as calculators and computers improved things they also introduce another problem. Many formatted test certificates quote all data to the same number of decimal places on chemical analysis, so all values will have 4 decimal places even if the method of testing doesn't test to that level of accuracy. A digital ultrasonic testing machine will test and show a result to as many decimal places as the manufacturer wishes to make it show (I have seen three places) but on stainless steels you have no way to calibrate the machine to anything like that accuracy. Micrometers are now digital and will read to 2 decimal places maybe more but unless it is a precision machined parallel piece you will never get the same reading twice because thickness itself is not consistent without the extra problem of ensuring it is seated correctly on a curved surface. Hardness testing has also been computerised, with the load applied hydraulically and a computer evaluating the indentation. Unfortunately in both Mannesmann GRW and the SVM research institute these miracles of technology produced results that were physically impossible despite being to an extra decimal place.


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## mikewint (Sep 27, 2019)

Pbehn - As I posted earlier I'm not in any of the trades or engineering so I can only go by the standards we were held to at the University when I was working on my degrees. Any and all test machines had manufacturer stated limits of accuracy and a result could only be as accurate as the least accurate measurement. In addition/subtraction all measurements had to be rounded to the greatest uncertainty before adding/subtracting. Multiplication/Division results were rounded to the same number of significant figures as the least number in the original data.
In a series of measurements Precision was another issue and final results were subject to a number of statistical analysis to determine whether they were statistically significant.
As of May 2019 SI has fixed the values of several fundamental physical "constants" so that they are now actually constant at least within a range of >20 parts per billion and in some cases >10 parts per billion. So, for example from the results obtained from 6 different Kibble Balances, Planck's Constant is now fixed at 6.62607015 X 10^-34 kg⋅m2/s with a 10 parts per billion uncertainty.


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## Barrett (Sep 27, 2019)

Several years ago the TransAmerican Free Trade Route (or something) was floated here in Arizona Territory with klics from the Border to somewhere around Tucson, changing to miles thereafter. (Maybe it was supposed to go as far as Vegas, baby.) At least that's what I recall from my phone inquiry to the relevant office. The civil servant on the other end was absolutely evangelical: offered/insisted on sending me Literature about the program when all I wanted was to know was whether the report I heard was true. Since then I've not been south of Tucson very much, and don't know how the "mile" markers are measured. 

Then there was the Japanese Navy which, I believe, measured distance in nautical miles, speeds in knots, and altitude in meters hooboy...


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## pbehn (Sep 27, 2019)

Barrett said:


> Then there was the Japanese Navy which, I believe, measured distance in nautical miles, speeds in knots, and altitude in meters hooboy...


The Japanese Navy was formed with the cooperation of the British when they were allies having distance and speed in nautical miles and knots isn't difficult to understand for a navy, a knot is a nautical mile per hour isn't it. It is one of the few measures based on the dimensions of the globe we actually live on the name "mile" is almost coincidental they are different units. A *nautical mile* is a unit of measurement used in both air and marine navigation,[2] and for the definition of territorial waters.[3] Historically, it was defined as one minute (1/60 of a degree) of latitude along any line of longitude.


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## wuzak (Sep 28, 2019)

mikewint said:


> Things may be different in the trades but IF the measurement is TRULY listed as 3230 mm then the terminal zero is NOT SIGNIFICANT. It is present only as a place-holder to move the left-most 3 into the tens column.



Maybe in calculations the 0 is not significant, but when two things have to fit together it is very significant.




mikewint said:


> The ruler used to make that measurement had a RESOLUTION of 100 mm (had actual marks every 100 mm) There were no marks on the ruler for Tens or Ones. Thus when the measurement was made the actual object ended between the 3300 and 3200 marks. I estimated that the amount above the 3200 mark was about 30 so I wrote 3200 + 30 = 3230 mm and the error would be half the uncertain digit or +/- 5 mm. So the object is somewhere between 3235 and 3225 mm.



Where did that come from?

Elmas mentioned that dimension in terms of a drawing. If you are making something according to a drawing dimensioned in mm you better not be using a measurement device with a resolution of 100mm. And you should not be estimating measurements.

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## Elmas (Sep 28, 2019)

wuzak said:


> Maybe in calculations the 0 is not significant, but when two things have to fit together it is very significant.
> 
> Where did that come from?
> Elmas mentioned that dimension in terms of a drawing. If you are making something according to a drawing dimensioned in mm you better not be using a measurement device with a resolution of 100mm. And you should not be estimating measurements.



Thanks Wuzak for the aid in explanation.
I didn't reply to some post because, to explain, I had to start from scratch.
So, let's begin...

*ERRORS*​
Errors are normally classified in three categories: systematic errors, random errors, and blunders.
*Systematic Errors*
Systematic errors are due to identified causes and can, in principle, be eliminated. Errors of this type result in measured values that are consistently too high or consistently too low. Systematic errors may be of four kinds:
1. Instrumental. For example, a poorly calibrated instrument such as a thermometer that reads 102° C when immersed in boiling water and 2° C when immersed in ice water at atmospheric pressure. Such a thermometer would result in measured values that are consistently too high.
2. Observational. For example, parallax in reading a meter scale.
3. Environmental. For example, an electrical power ìbrown outî that causes measured currents to be consistently too low.
4. Theoretical. Due to simplification of the model system or approximations in the equations describing it. For example, if your theory says that the temperature of the surrounding will not affect the readings taken when it actually does, then this factor will introduce a source of error.

*Random Errors*
Random errors are positive and negative fluctuations that cause about one-half of the measurements to be too high and one-half to be too low. Sources of random errors cannot always be identified. Possible sources of random errors are as follows:
1. Observational. For example, errors in judgment of an observer when reading the scale of a measuring device to the smallest division.
2. Environmental. For example, unpredictable fluctuations in line voltage, temperature, or mechanical vibrations of equipment.
Random errors, unlike systematic errors, can often be quantified by statistical analysis, therefore, the effects of random errors on the quantity or physical law under investigation can often be determined.
Example to distinguish between systematic and random errors is suppose that you use a stop watch to measure the time required for ten oscillations of a pendulum. One source of error will be your reaction time in starting and stopping the watch. During one measurement you may start early and stop late; on the next you may reverse these errors. These are random errors if both situations are equally likely. Repeated measurements produce a series of times that are all slightly different. They vary in random vary about an average value.
If a systematic error is also included for example, your stop watch is not starting from zero, then your measurements will vary, not about the average value, but about a displaced value.

*Blunders*
A final source of error, called a blunder, is an outright mistake. A person may record a wrong value, misread a scale, forget a digit when reading a scale or recording a measurement, or make a similar blunder. These blunder should stick out like sore thumbs if we make multiple measurements or if one person checks the work of another. Blunders should not be included in the analysis of data.

the rest is here
New Mexico State University - Department of Physics

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## mikewint (Sep 28, 2019)

wuzak said:


> And you should not be estimating measurements.


Since people are not perfect and neither are their machines it goes without saying that all measurements have UNCERTAINTY and in a correctly made measurement that uncertainty is in the terminal digit.
Next the edge (or whatever you are measuring) will always end up between two marked (on the instrument doing the measuring) marked lines. When you read the measurement from the instrument you start from the largest marked point and work your way down one marked line at a time until you come to the two lines that the actual object edge lies between. Here is where you ESTIMATE the value. There are no marked lines here so you have to estimate. So all correctly made measurement contain all digits known with certainty and ONE uncertain digit. These digits 1-9 are SIGNIFICANT DIGITS. ZERO however has TWO functions. ONE of those functions is its use as a PLACEHOLDER. Placeholder zeros are NEVER Significant as they were never read from an instrument. In 93,000,000 miles only the 9 and the 3 are significant the six zeros are place holders and the 3 digit was estimated and is a uncertain digit.
IF a terminal zero is to be significant you have to specifically indicate it so in 3450 cm the zero is a placeholder and the 5 is uncertain and there are 3 significant figures but in 3450. cm the zero is significant and is the uncertain digit so there are 4 significant figures


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## michael rauls (Sep 28, 2019)

Macandy said:


> “......We built Apollo using inches and put a man on the Moon.
> They built the Space Shuttle with the metric system and it blew up...”


I'm not aware of any evidence that the unit of measure used during the respective construction process of the two was ever suspected as the cause of the failures.

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## pbehn (Sep 28, 2019)

Elmas said:


> Thanks Wuzak for the aid in explanation.
> I didn't reply to some post because, to explain, I had to start from scratch.
> So, let's begin...
> 
> ...


There are a good few errors and reasons for them missed out there. Everyone understands what the diameter of a circle is. When it comes to the diameter of a pipe end there are many different ways to measure it for many different reasons. You have major problems when a client specifies a criteria and system of measurement without knowing why or the ramifications then doubles down on "the client is always right" when the people making their product try to give them advice. I spent far more of my life than I like to admit discussing ways to measure the diameter of a pipe end.


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## swampyankee (Sep 28, 2019)

michael rauls said:


> I'm not aware of any evidence that the unit of measure used during the respective construction process of the two was ever suspected as the cause of the failures.


It wasn't. Grissom, Chafee, and White didn't make it off the pad.


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## wuzak (Sep 28, 2019)

mikewint said:


> Since people are not perfect and neither are their machines it goes without saying that all measurements have UNCERTAINTY and in a correctly made measurement that uncertainty is in the terminal digit.
> Next the edge (or whatever you are measuring) will always end up between two marked (on the instrument doing the measuring) marked lines. When you read the measurement from the instrument you start from the largest marked point and work your way down one marked line at a time until you come to the two lines that the actual object edge lies between. Here is where you ESTIMATE the value. There are no marked lines here so you have to estimate. So all correctly made measurement contain all digits known with certainty and ONE uncertain digit. These digits 1-9 are SIGNIFICANT DIGITS. ZERO however has TWO functions. ONE of those functions is its use as a PLACEHOLDER. Placeholder zeros are NEVER Significant as they were never read from an instrument. In 93,000,000 miles only the 9 and the 3 are significant the six zeros are place holders and the 3 digit was estimated and is a uncertain digit.
> IF a terminal zero is to be significant you have to specifically indicate it so in 3450 cm the zero is a placeholder and the 5 is uncertain and there are 3 significant figures but in 3450. cm the zero is significant and is the uncertain digit so there are 4 significant figures



You are arguing from a theoretical point of view, not a practical point of view.

I've never seen a decimal point without a digit following it. But maybe that's just the engineering world where clarity is required.

if I draw something that is to be 3450mm then I expect it to be 3450mm +/- 0.5mm. The person making that thing will use a measuring device that has markings at 1mm increments, or better.

When I check the thing I would do the same. If the measurement falls between two lines, I determine whether it is closer to the upper of lower measurement. That is, if it is between 3450 and 3451 I don't estimate it to be 3450.3. If it is closer to 3450 it is OK and approved. If it is 3451 it will sometimes be OK, but other times it will be unacceptable - it depends what the thing is for and what, if anything, it fits to.

If the person who built the thing is like you and worked to 3 significant figures and the measurement is not an acceptable measurement, it will be rejected and sent back to be fixed or remade.

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## mikewint (Sep 29, 2019)

I cannot speak to the practicalities of the manufacturing or engineering end of things. Perhaps because in the sciences so many different types/kinds of instruments measuring so many different parameters were in use that it became incumbent that the experimenter state in specific terms the degree of uncertainty in each and every measurement. The sole problem is ZERO because of its dual usage both as a simple place-holder and in some cases an actual measurement digit.
We also used a BAR written over the last significant zero so 93,000,*Ō*00 miles would indicate that the three zeros after the 3 were actually measured and are therefore significant digits. The fourth zero (with the bar over it) is an estimated digit and therefore an uncertain digit though still significant. The last two zeros are placeholders and not significant.
It was also necessary to not have uncertainty wander all over the place so, for example, you made certain to use the same instrument all the time. So one would always use the same balance to measure mass so that its uncertainty was constant and in the same direction rather than one balance that read high followed by using a different one that read low.



wuzak said:


> I determine whether it is closer to the upper of lower measurement. That is, if it is between 3450 and 3451 I don't estimate it to be 3450.3. If it is closer to 3450 it is OK and approved


That's because you have that 0.5mm tolerance to play with. Your part is acceptable as long as the actual length falls between 3449.5 and 3450.5. So you might not actually write down the estimated .3 but you are cognizant of it none the less. And if that part is 3450.9 it has exceed tolerance and will need to be shaved down a bit.

The difference between us is that you were making something that had a practical direct use. If I'm measuring the speed of light through quartz then I don't have a fixed standard to compare my results against. All I can do is make several measurements and compare their precision. I can't find accuracy unless I have an accepted standard. So I measure to my instruments limits, perhaps 4 significant figures. A better instrumentality may later measure to 5 significant figures or better. As the significant figures increase and reading begin to cluster we can get an accepted value to a stated degree of error.
So the new Kibble Balances give us a Planck's Constant of: 6.62607015 × 10-34 kg⋅m2/s Many years ago I consistently used a value of 6.6262 for common calculations. Today that would be in error


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## fubar57 (Sep 29, 2019)



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## mikewint (Sep 29, 2019)

I'll see your eye roll and raise you a tongue:


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## fubar57 (Sep 29, 2019)

At least we know you can copy/paste a Gif as well

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## DerAdlerIstGelandet (Sep 29, 2019)

fubar57 said:


> At least we know you can copy/paste a Gif as well


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## michael rauls (Sep 29, 2019)

I used to run a CNC lathe many, many years ago( one of the many jobs I tried out but didn't particularly care for).
I used to just measure the parts the way they told me with the calipers they gave me. If the parts were within tolerance they went into the good bucket if not into the reject bin they'd go and id adjust the X or Y axis as needed and try again until good.
Seemed like a fairly simple job at the time.
Never realized making parts could get so complicated.

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## pbehn (Sep 29, 2019)

michael rauls said:


> I used to run a CNC lathe many, many years ago( one of the many jobs I tried out but didn't particularly care for).
> I used to just measure the parts the way they told me with the calipers they gave me. If the parts were within tolerance they went into the good bucket if not into the reject bin they'd go and id adjust the X or Y axis as needed and try again until good.
> Seemed like a fairly simple job at the time.
> Never realized making parts could get so complicated.


You would not believe the hours I have spent in rooms full of engineers discussing go-no go gauges (which is what I presume those calipers were). Also drifts, tapes calipers, lasers and all things used to measure pipe ends. I frequently noted that about a quarter of the people there didn't know what they were measuring and or why. It actually is complicated. What you were doing is quality control, adjusting x and y axis before you had to put stuff in the reject bin is quality assurance.

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## mikewint (Sep 29, 2019)

I was told many years ago that the reason some cars ran forever and never had a significant mechanical problem while others were lemons from day one was due to the way in which part tolerances came together randomly in the assembly process. By chance a car would come along where all over tolerances were matched with all under tolerances. Or the reverse where everything was at the limit of too big or too small.
When we rebuilt an engine we'd buy 40 pistons, for example, and weigh and mic each and every one until we had a set of eight that were identical. The rest were returned. The same with valves, push rods, piston rods, rockers. etc. The running engine had just about zero vibration


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## michael rauls (Sep 29, 2019)

pbehn said:


> You would not believe the hours I have spent in rooms full of engineers discussing go-no go gauges (which is what I presume those calipers were). Also drifts, tapes calipers, lasers and all things used to measure pipe ends. I frequently noted that about a quarter of the people there didn't know what they were measuring and or why. It actually is complicated. What you were doing is quality control, adjusting x and y axis before you had to put stuff in the reject bin is quality assurance.


Yes, I was just running parts and making minor adjustments to the program as needed to keep them within tolerance.
This was back when I was about 19 or 20 and had just tacken some machining in general and Cnc in particular at the local junior college. It never did occur to me just how much might have gone into getting it to that point.

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## pbehn (Sep 29, 2019)

mikewint said:


> I was told many years ago that the reason some cars ran forever and never had a significant mechanical problem while others were lemons from day one was due to the way in which part tolerances came together randomly in the assembly process. By chance a car would come along where all over tolerances were matched with all under tolerances. Or the reverse where everything was at the limit of too big or too small.
> When we rebuilt an engine we'd buy 40 pistons, for example, and weigh and mic each and every one until we had a set of eight that were identical. The rest were returned. The same with valves, push rods, piston rods, rockers. etc. The running engine had just about zero vibration


That is a difference the Japanese (and others) made in production engineering, narrowing down the variance in machined tolerances.


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## tyrodtom (Sep 29, 2019)

mikewint said:


> I was told many years ago that the reason some cars ran forever and never had a significant mechanical problem while others were lemons from day one was due to the way in which part tolerances came together randomly in the assembly process. By chance a car would come along where all over tolerances were matched with all under tolerances. Or the reverse where everything was at the limit of too big or too small.
> When we rebuilt an engine we'd buy 40 pistons, for example, and weigh and mic each and every one until we had a set of eight that were identical. The rest were returned. The same with valves, push rods, piston rods, rockers. etc. The running engine had just about zero vibration



I've been circle track racing for 30 years, built many engines myself, and been in on building a bunch more.
The approach of sending back more parts than you buy would make you a unwanted customer/client with any parts suppliers I've dealt with, and would quickly get you blackballed with any other supplier. These guys do talk to each other you know. 

The way me and my friends balance a engine is balance a set of rods, small and big ends, by machining the pads on the ends intended for that, until we get the rods as close to equal as possible, then do the same with the pistons. 
Then put the lightest rod with the heaviest piston, etc until we assemble the engine, if there's any difference left, it's corrected by balancing the crank dynamically.

Big NASCAR race shops do buy pistons, etc. in big bunches, and try to sort them out by equal weights as close as possible. Then use the same approach we do.
They only return defective parts.


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## Elmas (Sep 30, 2019)

In 1988 I bought in the same day from the same car dealer two absolutely identical Fiat Uno






one for me and one for my Wife, as they were very handy to use in the crowded and narrow streets of my City.






After three years my Wife told me _“..bring my car to the garage, the crank for lifting the driver’s glass is broken…”_
Exactly three days after the crank of my Uno car broke also.
Has anybody heard of _“ programmated obsolescence”_?

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## pbehn (Sep 30, 2019)

Elmas said:


> In 1988 I bought in the same day from the same car dealer two absolutely identical Fiat Uno
> 
> View attachment 554704
> 
> ...


It is caused by the genetically engineered crank weevil that takes three years to munch through a crank.


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## michael rauls (Sep 30, 2019)

mikewint said:


> I was told many years ago that the reason some cars ran forever and never had a significant mechanical problem while others were lemons from day one was due to the way in which part tolerances came together randomly in the assembly process. By chance a car would come along where all over tolerances were matched with all under tolerances. Or the reverse where everything was at the limit of too big or too small.
> When we rebuilt an engine we'd buy 40 pistons, for example, and weigh and mic each and every one until we had a set of eight that were identical. The rest were returned. The same with valves, push rods, piston rods, rockers. etc. The running engine had just about zero vibration


I think there's alot of truth that with some bad luck you can get a hold of a car that just by chance ended up with a whole lotta parts that are at the edge of tolerance( and maybe a few that are over) and therefore a real lemon.
I've never heard anything but good things about Subarus so we bought one. Mistake.
We got it brand new and within a few months it had engine troubles, brakes trouble, transmission trouble, and died occasionally when pulling up to a light.
Took it back to the dealer a couple times and even they couldn't fix it. We just traded it in on a Toyota truck a couple weeks ago.


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## Elmas (Sep 30, 2019)

pbehn said:


> It is caused by the genetically engineered crank weevil that takes three years to munch through a crank.



No, I think it was one of the early effects of the Climate Change. The crank wasn't designed for such hot temperatures.

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## mikewint (Sep 30, 2019)

tyrodtom said:


> The approach of sending back more parts than you buy would make you a unwanted customer/client with any parts suppliers


Well its been close to 60 years so I can 'fess up'. In Chicago one of the biggest auto parts retailers was Warshawsky or J C Whitney. One of my best friends was a Parts Manager. Everything I bought was through him. Generally all parts were graded as Good - Better - Best. So I'd call him and order Good and he'd put Best in the box. So while I took home 30 of their Best pistons I was only charged for the 8 I kept the rest went back on Monday and were never charged.
Had another friend in a tire retailer shop. I'd order the smallest cheapest and he'd bring out the biggest and best tires they had in the store.
Was the only way I could afford that beast


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## BobB (Oct 3, 2019)

gumbyk said:


> It shouldn't be, from a pilot's perspective. All you're looking for is the number on approach. I fly a Tiger Moth in mph, a Nanchang in km/h and any GA aircraft in knots, never had any problem as e.g. approach speed is 60 in the Tiger - 150 in the 'chang.


The Spanish Air Force flew both T-6's and SNJ's. They kept mph in the T-6's and knots in the SNJ's. I wonder if they kept a single type in a particular squadron but I don't know. The training school used T-6G's so they would have been consistent in mph.


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## BobB (Oct 3, 2019)

When I was in college, a very old professor expressed the opinion that English units were better in the machine shop. One hundredth of an inch (.010) is a good unit for non-precision work and readable on a scale. One thousandth of an inch is good for precision work. One centimeter is too big for non-precision work. One millimeter (.04") is a bit big for non-precision machine work. One tenth of a millimeter is too small for non-precision but too big for precision. Anyway, I'm convinced that the metric system is a Commie plot just like fluoride in water. It's no coincidence that when they add fluoride to water, they measure it in mg/liter.

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## DerAdlerIstGelandet (Oct 3, 2019)



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## pbehn (Oct 3, 2019)

BobB said:


> When I was in college, a very old professor expressed the opinion that English units were better in the machine shop. One hundredth of an inch (.010) is a good unit for non-precision work and readable on a scale. One thousandth of an inch is good for precision work. One centimeter is too big for non-precision work. One millimeter (.04") is a bit big for non-precision machine work. One tenth of a millimeter is too small for non-precision but too big for precision. Anyway, I'm convinced that the metric system is a Commie plot just like fluoride in water. It's no coincidence that when they add fluoride to water, they measure it in mg/liter.


It is easier than motes per cubic barleycorn.

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## Macandy (Oct 3, 2019)

michael rauls said:


> I'm not aware of any evidence that the unit of measure used during the respective construction process of the two was ever suspected as the cause of the failures.




That loud Woosh! You heard was an engineers joke going right over your head.


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## michael rauls (Oct 3, 2019)

Macandy said:


> That loud Woosh! You heard was an engineers joke going right over your head.


Um..........my post was also a joke. Thought that would be obvious. ..........obviously the unit of measure has nothing to do with it one way or the other..............woooosh


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## pbehn (Oct 3, 2019)

BobB said:


> It's no coincidence that when they add fluoride to water, they measure it in mg/liter.


A litre of water weighs a kilo, that used to be the definition of a litre, so a dilution of milligrams into litres is much easier to calculate.


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## tyrodtom (Oct 3, 2019)

BobB said:


> When I was in college, a very old professor expressed the opinion that English units were better in the machine shop. One hundredth of an inch (.010) is a good unit for non-precision work and readable on a scale. One thousandth of an inch is good for precision work. One centimeter is too big for non-precision work. One millimeter (.04") is a bit big for non-precision machine work. One tenth of a millimeter is too small for non-precision but too big for precision. Anyway, I'm convinced that the metric system is a Commie plot just like fluoride in water. It's no coincidence that when they add fluoride to water, they measure it in mg/liter.


 I went to tech school with a guy who believed the metric system was a commie plot to weaken America.
He was a young married guy, just had a single cab pickup with a camper.
His mother and dog rode in the cab with him, his wife and kid rode in the camper.
Let's just say his thinking processes were a little flawed, that marriage didn't last long.


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## Elmas (Oct 4, 2019)

In his early career my Father was a surveyor and when I was a boy in the summer very often I went with him to the building site to earn some pocket money. My duty was to keep vertical and steady the stadia rod.






When we had to plant the pickets He had his own particular unit that involved "hair". When the movement of the picket had to be an extremely tiny one the hair was specified as belonging to a particular area of the female human body.

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## pbehn (Oct 4, 2019)

Elmas said:


> In his early career my Father was a surveyor and when I was a boy in the summer very often I went with him to the building site to earn some pocket money. My duty was to keep vertical and steady the stadia rod.
> 
> View attachment 555379
> 
> ...


Funny you should say that, I was taught ultrasonics by C.J. Abrahams pioneer of many ultrasonic inspection and sizing techniques. His preferred unit of measure was obtained from a cats penis. Using his sizing technique would always get you within a cats cock hair of the correct result.


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## mikewint (Oct 4, 2019)

BobB said:


> metric system is a Commie plot just like fluoride in water.


In 1861 Commie Agents armed with #1, The Metric System and #2 about 2,000 tons of CaF2 infiltrated the US. Traveling first to Colorado Springs where they located the towns aquifer. Digging down several hundred feet they buried about 500 tons of the CaF2 into the aquifer. Next they traveled to Oakley, Idaho locating a warm spring about 5 miles from the town the once again contaminated the spring with CaF2. Lastly and most insidious they traveled to Bauxite, Arkansas where ALCOA was building a company town to mine and process bauxite to produce Aluminium metal. Once again the heinous Communists contaminated the nearby aquifer with CaF2. Unfortunately for the Commie Plotters the Civil war was ending and they could no longer do their dastardly deeds unnoticed.
The CaF2 slowly dissolved in the aquifer entering the towns water supply. Soon children began to me born with discolored brown teeth. No self-respecting White-tooth wanted anything to do with the brown-tooths so inbreeding began. The brown teeth proved almost immune to tooth decay and so the brown toothers ate better and lived longer. In Bauxite Arkansas rumors were spread that it was Aluminium causing the brown teeth...Aluminium must be poisonous and more and more people began to reject anything made of the new metal.

1901 Frederick McKay a young dentist moved to Colorado Springs and was appalled at the number of chocolate brown toothed people and children in the town AND the fact that these brown teeth did not decay. He began to searcher the condition which he named Colorado Brown Stain.

In 1909 a world renown dental researcher G V Black arrived to assist with the research. McKay began to suspect something in the town water was to blame.
In 1923 McKay heard of the brown-toothed residents of Oakley, Idaho and was able to convince the town leaders to give up the sprig that they were using for the town's water and move to another spring. Within a few years newly born children had normal white teeth. McKay now knew that it was something in the water but could find nothing. Then the Brown-toothed residents of Bauxite, Arkansas drew McKay's attention. McKay called in Dr, Grover Kempf of the USPHS to assist but neither was able to find the problem. The reports produced by McKay and Kempf caught the attention of ALCOA's Chief Chemist H V Churchill who had been fighting claims that Aluminium was poisonous for years. Churchill decided to do a much more through testing of Bauxite's water supply using a Photospectrographic analysis. At last success and Churchill reported to McKay that the towns water contained high levels of FLUORIDE. Water samples from Colorado Springs and Oakley showed the same high levels of Fluoride.

In 1931 Dr. H. Trendley Dean, head of the Dental Hygiene Unit at the National Institute of Health began investigating the epidemiology of fluorosis and its effects on tooth enamel. Dr. Elias Elvove, a senior chemist at the NIH had developed a test for Fluoride in water accurate to 0.1 ppm. Through these studies it was determine that Fluoride levels of 1.0 ppm did not cause the brown-stains and still maintained the decay resistant teeth.

In 1944 Dean, the US Surgeon General, and the Michigan Dept. of Health convinced the City of Grand Rapids to add Fluoride to the cities drinking water. In a 15-year study 30,000 children born after the addition of fluoride were monitored for tooth decay. Tooth decay in Grand Rapids had dropped by over 60%.
Dean had not only foiled the Communist plot but it had yielded an unexpected added boon.

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## gumbyk (Oct 6, 2019)

mikewint said:


> In 1861 Commie Agents armed with #1, The Metric System and #2 about 2,000 tons of CaF2 infiltrated the US.



Was that metric tons or imperial?


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## swampyankee (Oct 6, 2019)

mikewint said:


> In 1861 Commie Agents armed with #1, The Metric System and #2 about 2,000 tons of CaF2 infiltrated the US.



It's amazing that these commie agents were able to infiltrate anything in 1861, what with the secesh and copperheads taking up so much space.


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## pbehn (Oct 6, 2019)

swampyankee said:


> It's amazing that these commie agents were able to infiltrate anything in 1861, what with the secesh and copperheads taking up so much space.


 Of course the commie agents first took over the schools of Marx and Engels.

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## XBe02Drvr (Oct 7, 2019)

Elmas said:


> View attachment 555379
> 
> 
> When we had to plant the pickets He had his own particular unit that involved "hair". When the movement of the picket had to be an extremely tiny one the hair was specified as belonging to a particular area of the female human body.


Black=.005, Red=.003, Trueblonde=.001, as in "Down one TCH and hold!" An ancient and long established standard of measurement.

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## The Basket (Oct 7, 2019)

It is funny the comments 
Even the jest. 
It ain't no unit of measurement. 
Its spilling me pint and slapping me bird. 
Sounds like if metric became the mandated standard in the US of A, sounds more like an act of civil war than a standardised unit. 

This is the problem today. Too many people willing to lose their knicker elastic over the most mundane and trivial. 

No wonder any political discussion turns into excrement.

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## XBe02Drvr (Oct 7, 2019)

The Basket said:


> This is the problem today. Too many people willing to lose their knicker elastic over the most mundane and trivial.


"Them thea's fightin wouds, Suh! When ouah Prez gets you-all stratend out, th hole dam worll gonna see thins ouah way!!


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## The Basket (Oct 7, 2019)

Excuse me sir but Imperial is the British way! That's our units!

Goddam culture appropriation and no mistake. U be speaking English next.

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## Elmas (Oct 7, 2019)

XBe02Drvr said:


> Black=.005, Red=.003, Trueblonde=.001, as in "Down one TCH and hold!" An ancient and long established standard of measurement.



Oh, that’s from ancient Roman times...

Here an application...








_Post scriptum_
The word mile (miglio in Italian) derives from the Latin expression "milia passuum", "thousands of steps", which in ancient Rome indicated the unity equal to a thousand steps.
A Roman Legion was composed of tall and short men so the distance traveled with 1000 steps was more or less the same for all Legions.
It should be remembered that for the ancient Romans the “passus” was intended with the distance between the point of detachment and the point of support of the same foot during the journey, therefore double compared to the modern meaning.
Pitch 1.48 meters
Roman mile 1000 steps -> 1448 meters

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## mikewint (Oct 7, 2019)

Elmas said:


> therefore double compared to the modern meaning.


While PASSUS can be translated as STEP in this context it is more correct to use the term PACE. Much as in the modern military a PACE is every time your left foot hits the ground as in: RIGHT - LEFT....RIGHT - LEFT
A persons STRIDE length is directly related to their height. STEP LENGTH / HEIGHT = STRIDE. The Roman legions tended to recruit the tallest men so most Roman Legionaires were 5'7" - 5'8" so much like today a STRIDE was about 30 inches and a PACE 60 inches or 5 feet. Obviously a fully loaded Legionaire was not striding as far in the afternoon as in the morning so Roman engineers developed a wheeled cart whose wheels turned a gear which dropped a small pebble into a bucket every time the 5 foot circumference wheel made one revolution (a simple ODOMETER). Put 1000 pebbles in the top bucket and when the last one falls you've covered a 1000 paces or 5000 feet no matter how many paces it actually took.

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## pbehn (Oct 7, 2019)

It doesn't matter if it is 1000 paces as long as they are all the same or close to the same. Experience will use that as a guide to how far you can get in a day depending on what you are carrying and what the weather is like.


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## PWR4360-59B (Oct 9, 2019)

I love it the metric system for liquid measurements and for a tape measure and thats it.


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