Nikolai Ivanovich Lobachevsky (December 1, 1792 – February 24, 1856 (N.S.

); November 20, 1792 – February 12, 1856 (O.S.))

is a Russian mathematician and geometer, renowned primarily for his pioneering works on hyperbolic geometry, otherwise known as Lobachevskian geometry.

William Kingdon Clifford called Lobachevsky the "Copernicus of Geometry" due to the revolutionary character of his work.

(E. T., Bell (1986).

Men of Mathematics.

Touchstone Books.

p. 294.

ISBN 978-0-671-62818-5.

Author attributes this quote to another mathematician, William Kingdon Clifford.)