More about contractions:
Inserting space before apostrophes in contractions in the Osgood company's
1883 first American edition of "Life on the Mississippi" was an accepted
(and often recommended) style of rendering certain contractions in the
nineteenth century. It was house style for the "Atlantic Monthly" and for
the house that set "The Stolen White Elephant" and "Life on the
Mississippi" (University Press: John Wilson and Son, Cambridge).

Theodore Low DeVinne (the typesetter for the Century Company) explained the
principles at work and showed his preferred style in his 1901 edition of
"Correct Composition" (New York: The Century Company):

"The apostrophe indicates the omission of letters in dialect, in familiar
dialogue, and in poetry, as in

I 'll for I will                does n't for does not
I 've for I have                't was for it was
'em for them            ne'er for never

When two words are practically made into one syllable a thin space may be
put before the apostrophe, as in I 've, I 'll. The phrases don't, can't,
won't, and shan't are exceptions, and are consolidated. There are many
cases in which a separating space is needed to make more apparent the
difference between the possessive s and the contraction of is, as in

Where truth 's unknown and honor 's dead." (De Vinne, 285)

If the Braille transcribers preserve the spaces in contractions in their
transcriptions, there is at least enough information to include a note of
explanation. If preserving the spaces is likely to cause difficulty for
Braille readers, however, and you decide to delete them, it might help to
know that spacing contractions was not Mark Twain's preferred style and
does not appear in his manuscripts (except very occasionally). The style
was imposed on his "Mississippi" printer's copy by the typesetters.

Victor Fischer
Mark Twain Project