As above. English spellings of german words where the vowel has an "umlaut" often add an e after the vowel to approximate the effect of the "umlaut" on the vowel sound. I'm guessing in the age of print the umlaut symbol was unavailabe to English printers.
The correct spelling is Bar with the umlaut but on the UK english keyboard I'm using now I would have to type Baer.
From Wikipedia.
"Um"+"laut" is German for "around/changed"+"sound". It refers to a historical sound shift in that language. In German, the umlaut diacritic is found as ä, ö and ü. The name is used in some other languages that share these symbols with German or where the Latin spelling was introduced in the 19th century, replacing marks that had been used previously. The phonological phenomenon of umlaut occurred historically in English as well (man ~ men; full ~ fill; goose ~ geese) in a way cognately parallel with German, but English orthography does not write the sound shift using the umlaut diacritic. Instead, a different letter is used.
Cheers
Steve