Fred,

This stuck in my mind as being much prior to 1904, so  I did a search of my
current WIP (Mark Twain Day-by-Day) and found I'd  referenced this remark by
Wecter, _Sam Clemens of Hannibal_ page 154.   However, Wecter references the
following on this page:

---
_Autobiography_, I, 109 and II, 99-102; MTP, Paine  154, "Concerning a
Reformed Pledge," dated Hartford, Christmas 1886; MTP, Paine  255,
"Conversations
with Satan," written in Vienna about 1898. His most explicit  statement
about
the use and benign effects of tobacco, dated March 14, 1882, was  written
for
_Study and Stimulants_, ed. A. Arthur Read, pp. 120-22.
--

AS with many Western slang words and expressions, Sam  may not have been the
first to coin them, but gave them currency. A great  article from 1947 that
lists the many expressions credited to Sam (such as "like  rolling off a
log")
and traces their early use, is:

"The Background of Mark Twain's Vocabulary," by  Charles J. Lovell,
_American
Speech_ Vol 22, No 2 (April, 1947) pp 88-98.  Available on JSTOR.