A. MATHEMATICS AND ASTRONOMY. 29 



lation of these meteorites and their contained o-ases to the 

 modern theory of comets is certainly of great interest. 

 4 D, Aprils 1876, 262, and July, 1875. 



THE ATMOSPHERE OF VENUS. 



Mr. H. C. Russell, government astronomer to New South 

 Wales, in giving an account of the observations made by the 

 various parties stationed there on the transit of Venus, goes 

 into some detail on the subject of the observed halo about 

 the planet Venus, and its possible explanation. Most of the 

 observers state that for some minutes before the first inter- 

 nal contact the whole of the planet's outline could be seen, 

 and three distinct phenomena appeared to be distinguishable: 

 First, a broad ring of light, outside of the planet ; second, a 

 bright ring of light around that part of the planet projected 

 on the sky; third, a band of light around the inner edge of 

 the planet, or over its surface. No spots were seen on the 

 planet. The first, or halo, seems to Mr. Russell not likely to 

 be due to any atmosphere. It is a phenomenon, in fact, seen 

 only by some observers and under special conditions. The 

 second, or bright ring, is the most interesting physical feat- 

 ure observed ; although at first it would seem to be due to 

 an atmosphere somcAvhat similar to that of the earth, yet Mr. 

 Russell thinks that a little consideration will show that it can 

 not have such an origin. It is spoken of by all observers as 

 very brilliant, and its actinic power was so great that, al- 

 though it could appear only as a fine line in the photo-helio- 

 graph less than 0.002 of an inch in diameter, it yet had power 

 to affect the chemicals in something less than the 0.004 part 

 of a second. In other words, it was quite as powerful, even 

 more so, than direct sunlight. Mr. Russell thinks that an 

 envelope of some perfectly translucent substance, such as 

 water, would alone suffice to account for all the observed 

 facts. Trans. Roy. Soc. of New South Wales, 1874, 111. 



DIAMETERS OF THE INFERIOR PLANETS AS AFFECTED BY 



DIFFRACTION. 



Andre, of the Observatory of Paris, has undertaken a re- 

 search on the diameters of Venus and Mercury as afi'ected 

 by the phenomenon of instrumental diffraction, in connection 

 with the observations of the transit of Venus in 1874, which 



