In an earlier discussion it was suggested that Twain's reference
to "kicking the Irish Giant's eye" might have been a reference
to Patrick Cotter (1760-1805).  A later news article that
Clemens wrote for the San Francisco Daily Morning Call makes
another mention of the Irish Giant.  He writes:

The grand discharges of rockets, however, and their bursting spray of
many-colored sparks, were visible to all, after they had reached a
tremendous altitude, and these gave pleasure and brought solace to many a
sorrowing heart behind many an untransparent vehicle. Still we know that
the fireworks on the night of the Fourth, mottoes, temples, stars,
triangles, Catherine wheels, towers, pyramids, and, in fact, every
department of the exhibition, formed by far the most magnificent spectacle
of the kind ever witnessed on the Pacific coast. The reason why we know it
is, that that infamous, endless, Irish giant, at Gilbert's Museum, stood
exactly in front of us the whole evening, and he said so.
(San Francisco Daily Morning Call, July 6, 1864)

Perhaps there was a Gilbert's Museum in San Francisco exhibiting a
contemporary Irish Giant in 1864?

Barb