Theorie der Parallel-Linien

Year of Conception:    ?
Year of Writing:            September 1766
Year of Publication:    1786

Subject:
Geometry

Publication:
Theorie der Parallel-Linien. Leipziger Magazin für reine und angewandte Mathematik, Band I, 137-164. Fortsetzung der Parallel-Linien. Leipziger Magazin für reine und angewandte Mathematik, Band I, 325-358.(3)
Reprinted in: F. Engel and P. Stäckel (eds.), Urkunden zur Geschichte der Nichteuklidischen Geometrie, Leipzig, 1895, 152-208.(3)

Description:

Lambert's famous essay on the parallel postulate. He assumes variants of the postulate (there is no resp. infinitely many parallel(s)) and tries to deduce a contradiction. Even after many deductions Lambert is unable to find a contradiction, but has on the contrary derived many qualities and theorems that suggest other geometries, one that resembles spherical geometry (elliptic geometry) and one that seems to be on an "imaginary sphere" (hyperbolic geometry).

Reviews: ADB 1786, 174-175 and 468-469(6)