A. MATHEMATICS AND ASTRONOMY. 33 



ton. An appendix to the report contains miscellaneous com- 

 munications upon the galvanic battery, the total eclipse of 

 the sun of August 2, 1869, and the meteoric showers of 1867, 

 etc. ; and the whole book must be considered a very valuable 

 contribution to physical science. 



NAMING NEW ASTEROIDS. 



Professor Peters has named the two planets lately discov- 

 ered by him (Nos. 122 and 123) Gerda and Brunhilda,and com- 

 municates to the American Journal of Science the elements 

 of their orbits. The orbit of Gerda is remarkable for having 

 both the inclination and eccentricity very small a coinci- 

 dence not found in any other known asteroids except in the 

 case of Clytia. The planet No. 124 is now known as Alceste, 

 and at the time of Dr. Peters's communication had the ap- 

 pearance of a star of a little less than the eleventh magni- 

 tude. 4 D, November, 1872, 400. 



CHANGE OF SPOTS IN LUNAR CRATERS. 



Mr. Birt reports as to the result of observations upon the 

 spots on the floor of the crater Plato, on the moon's surface, 

 that decided changes have taken place since the investigation 

 was first undertaken, and gives an account of the observations 

 on the streaks and colors of the floor. The changes in the 

 direction and luminosity of the streaks detected were of such 

 a character that they could not be referred to changes of il- 

 lumination, but depended upon some agency connected with 

 the condition of the moon itself. The color of the floor was 

 found to vary as the sun ascended in the lunar heavens, being 

 darkest with the greatest solar altitude. It is thought prob- 

 able, if farther observations upon the spots can be made, that 

 streaks and changes of an interesting character will be dis- 

 covered. 15 A, Proc. Brit. Assoc, August 24, 1872, 237. 



THE RINGS OF SATURN. 



The rings of Saturn have always been an enigma to astron- 

 omers. La Place showed that if they were solid, and of the 

 same thickness throughout, they would soon fall down on the 

 planet and be destroyed. He therefore supposed them of ir- 

 regular density. Not many years ago Professor Peirce found 

 that the same catastrophe would occur even in this case, and 



B 2 



