214 HEESCHEL. 



This peculiar tact Herscliel possessed iu aii eminent degree. Moreover, 

 the result deduced from the very small number of proper motions known 

 at tlie beginning of 1783, has been found almost to agree with that found 

 recently by our best astronomers, with the application of subtile 

 analytical formulae, to a considerable number of exact observations. 



The proper motions of the stars have been known for more than a 

 century, and even Fonteuelle used to say, in 1738, that the sun has pro- 

 bably a similar motion. The idea of partly attributing the displace- 

 ment of the stars to a motion of the sun had suggested itself to Bradley 

 and to Mayer. Lambert especially had been very explicit on the subject. 

 Until then, however, there were only conjectures and mere probabilities. 

 Herschel i)assed these limits. He proved that the sun himself posi- 

 tively moves, and that in this respect that immense and dazzling body 

 must also be classed among the stars; that the apparently inextricable 

 irregularities of numerous sidereal proper motions arise in great 

 measure from the displacement of the solar system; that, in short, the 

 point of space toward which we are annually advancing is situated in 

 the constellation of Hercules. 



These are magnificent results. The discovery of the proper motion of 

 our system will always be accounted among Herschel's highest claims to 

 glory, even after the mention that my duty as historian has obliged me 

 to nmke of the anterior conjectures of Fonteuelle, of Bradley, of Mayer, 

 and of Lambert. 



By the side of this great discovery we should place another, that seems 

 likely to be expanded in future. The results which it allows us to hope 

 Ibrwill be of extreme importance. The discovery here alluded to was 

 announced to the learned world iu 1803 ; it is that of the reciprocal de- 

 pendence of several stars, connected the one with the other, as the 

 several planets and their satellites of our system are with the sun. 



Let us to these immortal labors add the ingeuious ideas that we owe 

 to Herschel on the nebuliB, on the constitution of the Milky Way, on the 

 universe as a whole — ideas which almost by themselves constitute the 

 actual history of the formation of the worlds — and we cannot have too 

 deep a reverence for tluit powerful genius that notwithstanding the 

 play of an ardent imagination scarcely ever erred. 



LABORS RELATIVE TO THE SOLAR SYSTEM. 



Herschel devoted much time to the sun, but only relative to its physical 

 constitution. The observations that he made on this subject, and the 

 consetpieuces that he deduced from them, equal in interest the most 

 ingenious discoveries for which the sciences are indebted to him. 



In his important memoir in 1795, the great astronomer declares him- 

 self convinced that the substance by the intermediation of which the 

 sun shines cannot be either a liquid or an elastic liuid. It must be 

 analogous to our clouds, and float in the transparent atmosphere of that 

 body. The sun has, according to him, two atmospheres, endowed with 



