O'CONNOR, J. L. // The peerless perpetual calendar. (Los Angeles, ca. 1900)
Perpetual calendar, composed of two printed sheets of card-stock (17 x 11 cm.). The pink top-sheet, featuring seven windows, moves up-and-down via two brass brads fit into a vertical slit in the mint-green backing sheet. Minor foxing to margins; otherwise remarkably well-preserved.
A clever paper-computer devised by "inventor and manufacturer" John Leo O'Connor, "by the aid of which we may accurately determine the day of the week corresponding to any date from the beginning of the Christian era to A.D. 1600, by the Julian calendar (old style), and from the commencement of the Gregorian calendar (new style), October 15, A.D. 1582, to A.D. 2699."
With no OCLC records discovered; from the author of The science of numbers simplified: a book of practical short rules in arithmetic (1900).