454 URBAIN-JEAN-JOSEPH LEVERRIER. 



the highest character of its kind. In phcenogamous botany, it related 

 chiefly to the Scandinavian flora, in which for critical judgment he 

 had no superior ; in Mycology, of which he was the reformator, and 

 to a good degree in Lichenology, he had no rival except as regards 

 microscopical research. The modern microscope did not exist when 

 he began his work, and, while showing how much can be done without 

 it, he may too long have underrated its value. Hut he lived to see it 

 confirm many conclusions which his insight foresaw, and solve riddles 

 which he had pondered, but was unable to divine. He was the prince, 

 Nestor, and last survivor of an excellent school of systematic botanists, 

 whose teachers were taught by Linnosus or his contemporaries. 



URBAIN-JEAN-JOSEPH LEVERRIER. 



Urbain-Jean-Joseph Leverrier was born at St. L6, in the de- 

 partment of the Manche, on March 11th, 1811. As a boy, he studied 

 at the colleges of St. L6 at Caen, and in Paris at the College of Louis 

 le Grand. In 1831, he entered the Ecole Polytechnique, where he 

 graduated with such distinction that he was allowed to choose which 

 branch of the public service he would enter. Obtaining a position 

 in the tobacco bureau, he devoted his leisure to chemistry, and pub- 

 lished, as his first contribution to science, two papers on the com- 

 binations of phosphorus with hydrogen and oxygen. Ilis natural 

 tastes, however, were in the direction of the mathematics, and soon 

 after, receiving a minor appointment in the Ecole Polytechnique, he 

 was enabled to devote his entire energies to his favorite science. At 

 the instigation of Arago, he undertook the examination of the mutual 

 disturbances of the planets, a subject to which he devoted a large por- 

 tion of his life. A complete discussion of the motion of a single planet 

 is a work of which any astronomer might be proud, but the determina- 

 tion of the motions, and the formation of tables for computing the 

 positions of all the planets is a work of such magnitude that it would 

 seem beyond the powers of a single individual. Yet LeVerrier not 

 only boldly undertook this problem, but carried it to a successful ter- 

 mination, and built himself a lasting monument in the superb volumes 

 of the " Paris Observatory," in which these researches are published. 



The discovery of Neptune, by which LeVerrier is best known to the 

 public, enters as a small portion of this great work. A study of the 

 discordance in the motion of the planet Uranus from its path, as given 

 by theory, led him to suspect the existence of an outer planet, pro- 

 ducing the disturbance by its attraction. An investigation of the mass 



