Lobachevsky (Nikolai Ivanovich) Geometrical Researches on the Theory of Parallels, translated from the original by George Bruce Halstead, second English edition, offprint issue, embossed stamp of Bowdoin College to upper wrapper, three punch holes to inner margin not affecting text, original wrappers, slight toning and crease to upper wrapper with contemporary ink manuscript note, housed in morocco-backed slip-case, Texas, 1891.

⁂ Second (but first obtainable) English edition of Lobachevky's non-euclidean geometry. It was preceded only by its virtually unobtainable printing in February 1891, in the short-lived and little-known journal Scientiae Baccalaureus, of which fewer than 10 institutional holdings of the journal are known, and only 2 copies of the offprint.