A. MATHEMATICS AND ASTRONOMY. n 



accurately with the F line of the solar spectrum; and the 

 coincidence of this dark line in the spectrum, of Uranus with 

 the bright line H/3 of a Geissler tube filled with hydrogen was 

 established. The broad band, whose wave length is from 578 

 to 565 millionths of a millimeter, and also the broad but faint 

 band beyond F, the middle of which has a wave length of 475 

 millionths of a millimeter, coincide quite accurately with ab- 

 sorption bands produced by our atmosphere, and observable 

 when the sun is low. The possibility that there might exist 

 in the atmosphere of Uranus some of the lower combinations 

 of oxygen with nitrogen induced Dr.Vogel to determine more 

 accurately the position of the absorption bands produced by 

 such combinations ; these, however, exhibited no satisfactory 

 agreement with the bands in the spectrum of Uranus. 19 (7, 

 December 2, 1871, 387. 



TRANSIT OF VENUS. 



As the period of the transit of Venus in 1874 approaches, 

 astronomers both at home and abroad are becoming more and 

 more active in their preparations, and the American commit- 

 tee on this subject, it is understood, has already decided in 

 considerable part upon the stations to be occupied. Of .the 

 result of their conclusions we hope to give an account before 

 long to our readers. In Russia the committee, under Profess- 

 or Struve, proposes the establishment of a chain of observ- 

 ers, at positions one hundred miles apart, along the region 

 comprised between Kamtschatka and the Black Sea. The 

 German committee has decided on recommending the organ- 

 ization of four stations for heliometric observations of the 

 planet during its transit, one of them in Japan or China, and 

 the others probably at Mauritius, Kerguelen, and Auckland 

 Islands ; and three of these, with the addition of a fourth sta- 

 tion in Persia between Mascate and Teheran, will be equipped 

 for photographic observations also. The French, before the 

 war, suggested that stations be established at St. Paul Islands, 

 New Amsterdam, Yokohama, Tahiti, Noumea, Mascate, and 

 Suez. How far this programme will be carried out under the 

 changed circumstances of that country remains to be seen. 

 The British preparations are said to be very far advanced, 

 owing to the interest taken in the matter by the astronomer 

 royal. The stations proposed by England are six in number 



