I’ve been comparing the spelling between the first edition (1869) of The Innocents Abroad, and the Author’s National Edition (which is copyright 1897 and 1899).

I’m curious if the changes in spelling were approved by Twain, in this edition, or other uniform editions (which I have not yet looked at). Has there been anything written about the changes between editions and how they came about?

Here are some of the changes I’ve noticed so far:

Spelling changes:

amphitheatre	amphitheater
ancle		ankle
centre		center
ecstacy		ecstasy
irruption		eruption
lettred		lettered
lustre		luster
meagre		meager
ploughed		plowed
pretence		pretense
spectre		specter
sceptre		scepter
staid		stayed
theatre		theater
woollen		woolen

Words combined:

any thing		anything
any body		anybody
any where	anywhere
every thing	everything
every body	everybody
every where	everywhere

While these were not combined:

any one
every one
near by

Also, pic-nic was changed to picnic, but to-day, to-morrow, and to-night were not changed.

Looking at some of the words in Google Books Ngram Viewer shows when certain spellings overtook others, which is kind of neat to see visually. In most cases these map pretty well to what was changed. If the spelling didn’t switch until after 1899, it wasn’t changed in the Author’s National Edition. For example, ‘everywhere' overtook 'every where’ already in the 1840s, and it is changed in the uniform edition. However, ‘everyone’ didn’t overtake ‘every one’ until the late 1920s, so it isn’t changed in the uniform edition.

Any other types of spelling changes I should be looking out for?

Thanks.

Philip