Named in honor of Johann Heinrich Lambert (1728–1777), who described the Milky Way as “the ecliptic of the fixed stars” and made other remarkably good cosmological guesses. His law of exponential absorption of light and his theorem regarding inferences from the curvature of the apparent paths of comets are still in use. He first proved the irrationality of π (1768) and he introduced the present hyperbolic function symbols and elaborated the new subject. (H 23) _ _.