3 i2 . NINETEENTH CENTURY. W. m. 



Anotlier important discovery, believed on good grounds 

 to have been made within the last few years, is that of one, 

 and perhaps two, planets revolving between Mercury and the 

 sun. We shall see presently that Leverrier's analysis of the 

 planetary orbits points to a probability that some bodies of 

 this kind exist nearer to the sun than Mercury, and in 1859 

 a French physician, M. Lescarbault, asserted that he had 

 seen a round body crossing the sun's disc which Leverrier 

 believed to be a planet, and called by the name of Vulcan. 

 During the eclipse of the sun on July 29, 1878, Professor 

 Watson of the Observatory of Michigan devoted all his 

 attention to a search for this planet, and though he did not 

 find it, he saw two other bodies which he believes to be 

 planets, but whose positions do not either of them agree 

 with that of Lescarbault's Vulcan, so that if future observa- 

 tion confirms these discoveries we should know of three 

 intermercurial planets. 



Leverrier's Analysis of the Orbits of the Planets, 

 1875. Thus far it has been the gradual perfection of 

 instruments, and the use of them in patient research, which 

 has given us our vantage ground. But meanwhile the 

 great mathematical minds have not been idle in demon- 

 strating that ' order is heaven's first law,' and after thirty-six 

 years of constant labour M. Leverrier has completed the 

 analysis of the movements of the eight large planets, so 

 that the student of astronomy has now before him a chart 

 by which he can check the actual revolutions in our 

 planetary system for two thousand years to come. It is 

 impossible for any but mathematicians properly to ap- 

 preciate this work, but we may form some idea of it by 

 picturing to ourselves the problem which Leverrier had to 

 solve. 



We must first of all remember the fact proved by New 



