Cartoonist Thomas Nast, who died in Ecuador in 1902, did not illustrate _Mark Twain's Burlesque Autobiography_. That book was illustrated by Henry Louis Stephens, a former owner and art editor of _Vanity Fair_. Stephens was popular as a cartoonist before Thomas Nast dominated the field and their work does look similar. There is a good entry on Thomas Nast and his acquaintance with Mark Twain in Kent Rasmussen's _Critical Companion to Mark Twain_. Barb