24 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



considered meteorites as belonging to three classes siderites 

 (principally iron), siderolites (iron and stone), and aerolites 

 (mostly stone). 



The components of meteorites embrace about one third of 

 the known elements. Mr. Maskelyne considers meteorites as 

 probably cosmical in their origin ; their velocity, however, he 

 thinks incompatible with a lunar or sublunar origin, while 

 their chemical constitution differs from that of the sun, as far 

 as at present known. 22 A, May 18, 1872, 478. 



THE DISCOVERERS OF ASTEROIDS. 



Mr. Richard A. Proctor calls attention to certain peculiari- 

 ties connected with the discovery of the 120 asteroids now 

 known to astronomers, and states that it is very remarkable 

 that the spring and autumn seem especially favorable for 

 their detection. Of the entire number no less than forty-five 

 were discovered in April and September. The average rate 

 of discovery has been rather more than four times as great 

 in April and September as in the midwinter and summer 

 months. Mr. Proctor can understand the poverty of discov- 

 ery in the midsummer months as due to the shortness of the 

 nights and the amount of twilight, and suggests that the cold 

 drives the observer from the telescope in the winter, so as to 

 materially affect the discoveries. Of the asteroids yet known, 

 Luther, of Bilk, in Germany, has discovered 20 ; Goldschmidt, 

 of France, 14; Professor Peters, of Hamilton College, New 

 York, 13; Professor Hind, of England, and Professor Wat- 

 son, of Ann Arbor, 10 each ; 67 being divided among five ob- 

 servers. Twenty astronomers share the honor of discovering 

 the remaining 53. 3 A, April 20, 1872, 332. 



LUNAR PHOTOGRAPHS. 



Very perfect photographs of the moon have been lately 

 obtained at the Melbourne Observatory, the original nega- 

 tives being three inches in diameter, and capable of enlarge- 

 ment to any desired dimensions. 12 A, July 18, 1872, 228. 



RECENT ADVANCES IN ASTRONOMY. 



In his address before the Mathematical and Physical Sec- 

 tion of the Brighton meeting of the British Association, Mr. 

 De La Rue considers the most important advancement in 



