I watch a lot of westerns about cowboys in the old west (US). It seems to me that there are many references to saving hides (of cattle, also heads of cattle, another way to refer to the number of animals) and conjecture that it's possible that the expression "save my ass" started out as "save my hide". This is the NGram chart that shows the usage overlap:
According to this chart, "save my ass" started to gain in popularity when usage of "save my hide" began to wane.
Abbreviations and contractions of words follow many conventions, take for example the word continued I have seen it abbreviated/shortened/contracted or clipped in three ways.
Mathematics can be similarly contracted
- math
- math.
- (math's) maths
Perhaps, originally, the written form with the apostrophe, math's, was more common in Great Britain but over time the apostrophe became obsolete. In fact the apostrophe in math's has no effect on its pronunciation. Unfortunately, I don't have access to the Oxford English Dictionary to confirm my suspicion that the term math's was ever used.
The Online Etymology Dictionary instead states that the American math first appeared in 1890 while the British maths is attested from 1911.
Wikipedia has this to say on contractions:
An abbreviation is a shortening by any method; a contraction is a
reduction of size by the drawing together of the parts. A contraction
of a word is made by omitting certain letters or syllables and
bringing together the first and last letters or elements; an
abbreviation may be made by omitting certain portions from the
interior or by cutting off a part. A contraction is an abbreviation,
but an abbreviation is not necessarily a contraction.
Further on, Wikipedia explains
In British English, according to Hart's Rules, the general rule is
that abbreviations (in the narrow sense that includes only words with
the ending, and not the middle, dropped) terminate with a full stop,
whereas contractions (in the sense of words missing a middle part) do
not.
Curious to see whether I could find the apostrophe version, I turned to Google Books and found to my surprise that math's existed in the US, this example is dated 1836, and predates Word Detective's claim that the first instance of math appeared in 1847.
Larry Trask who was professor of Linguistics in Sussex University (UK) mentions the most common shortened forms where the apostrophe still survives.
A few words which were contractions long ago are still conventionally
written with apostrophes, even though the longer forms have more or
less dropped out of use. There are so few of these that you can easily learn them all. Here are the commonest ones, with their original longer forms:
- o'clock, of the clock
- Hallowe'en, Halloweven
- fo'c's'le, forecastle
- cat-o'-nine-tails, cat-of-nine-tails
- ne'er-do-well, never-do-well
- will-o'-the-wisp, will-of-the-wisp
EDIT
Published in Richmond USA by William F. Richie, 1853-54, The Merit Roll of the Cadets of the Virginia Military Institute, July 1853 lists math's as the shortened form for mathematics twice!
Personal Reflections
As demonstrated in the excerpts I provided, it seems clear that the spelling convention for contracted words i.e., the use of the apostrophe for showing the omission of letters, was also used in the US. The shortened form math's was necessary in order to save space but for some reason the superfluous apostrophe and the letter -S were kept despite logic demanding that the word math was shorter. The question also arises whether this contracted word was ever actually spoken by Americans? My guess? Probably not, they chose not to say maths /maθs/ because it sounded plural and therefore opted for the clipped form, math /maθ/ in speech. The British, being renowned traditionalists, decided to keep the "silent" apostrophe in speech and thus favoured the longer form maths.
Best Answer
The spelling "fair do's" goes back well into the nineteenth century. The two earliest Google Books matches are from 1868 and 1872. From C.A. Wheeler, Sportascrapiana: Facts in Athletics, second edition (1868):
And from "Wilfred Wildblood," in The Raven Club Papers (1872):
Likewise, Henry Smith, "A Glossary of Words in Use in the Isle of Wight" (1881) uses that spelling:
As for the earlier variants noted by Hugo in his answer, the first occurs in a sports setting. From Thomas Hughes, The Scouring of the White Horse Or, The Long Vacation Ramble of a London Clerk (1859):
A second early instance of "fair doos" appears in Edward Burlend, Amy Thornton, or, The Curate's Daughter (1862):
And (again cited in Hugo's answer) from C. Clough Robinson, The Dialect of Leeds and Its Neighbourhood (1862):