The Antiquities of Wisconsin, Increase A. Lapham's most important published work, was the result of his interest in the Indian effigy mounds found on Wisconsin's Landscape. His research for the work was funded by the American Antiquarian Society and it was published in the Smithsonian Contributions to Knowledge series. Antiquities includes 92 pages of text, illustrated with 61 wood engravings, and 55 lithographed plates.