212 



ASTRONOMY. 



Frigga (77) was refoundby Peters on July 17, 1879, after having been 

 at large for several years. Prof. Petees suggests that Frigga may be 

 variable. 



The discoveries for ISSO were : 



Date. 



Ko. 



1880. 

 February 6 - 

 rebrnary 17 - 

 March 1 - - 

 April 7 - - • 

 April 10 - • 

 Angu.st30- - 

 September 4 - 

 September 30 



212 

 213 

 214 

 215 

 216 

 217 

 218 

 219 



Xame. 



Lilaea - 

 Oenone 



Discoverer. 



Palisa. 



Peters.* 



Palis*. 



KJnorre. 



Palisa. 



Cojrgia. 



Palisa. 



Palisa. t 



* His 41st discovery. 



tHis 28tli discovery. 



The Jahrhuch for 1882 gives some details regarding the first 173 as- 

 teroids, which we condense as follows : Out of these 173, there are 120 

 which have been satisfactorily observed at 5 (or more) oppositions, 11 

 which have been observed at 4 oppositions, 10 at 3, 14 at 2, and 18 at 1 

 only. Of theselast IS, someare new discoveries and only i)il-e(BoRELLY), 

 and Scylla (Palisa) are yet to be rediscovered. Jucica (WATS0^') has 

 been lately found, after having been lost six years. 



The Moon. — The lunar photographs taken with the 13-inch reflector at 

 the University Observatory, Oxford, have been utilized for finding a 

 new value for the semi diameter of the Moon. The process adopted was 

 very nearly the same as that employed by Wich^ian, and the resulting 

 mean semi-diameter is 15' 34" .175 + 0".0G9. Mr. Xeison has, from a 

 careful discussion of nearly 1,100 observations, made at Greenwich, Ox- 

 ford (Eadcliffe), and Washington, deduced the value — 



15' 33".37-f 4".10-r(l -f 0".70 x aperture in inches). 



This empirical formula, he adds, agrees closely with the theoretical 

 formula, founded on the assumpntion that the differences between the 

 semi-diameters obtained with instruments of difl:erent ajierture vary as 

 the diffraction discs and the amount of light. Applying the formula to 

 a 13-inch reflector, and adding the photographic irradiation, which ]\Ir. 

 XiESON states his experiments indicate to be about + 0".3, the photo- 

 graphic semi-diameter should be 15' 34". 08. 



Xo papers on the Moon published during the past year exceed in im- 

 portance those by Mr. G. H. Daevvin on the secular effects of tidal fric- 

 tion on the configuration of a i)lanet and its satelHte. In the first paper 

 the theory of the deformation of a viscous or imperfectly elastic spheroid 

 under the attraction of satellites is investigated. Kumericitl calculations 

 show that bodily tides in the Earth are at present very small. From this 

 pomt Mr. Baewix was led to consider the perttu'bed lotation of such 

 a spheroid, and the reaction on the perturbing bodies. He has in 

 the A. y. 2294 given the following summary of the results arrived at 



