144 ASTRONOMY FOK l«8i>, IHitO. 



])laii;itioii of meteors are ^iveii, and extensive catalogues of observed 

 meteors and meteorites. 



.Mr. Denninj; pointed out several years ago tliat there were a number 

 of meteor streams iu which the meteors seemed to radiate from the same 

 point in the sky for a period of three nionths or more. The o!iIy expla- 

 nation of this phenomenon seemed to be that the meteors were moving 

 with frightful velocity through si)ace, but jNI. Tisserand, from a mathe- 

 matical study of the problem, shows that these meteors do not all 

 come from the same stream ; they may perhaps belong to a family pre- 

 senting certain common characteristics, but they are in reality dilfeicnt 

 streams accidentally falling together, a uot very iMj[)i-obable assumption 

 considering the great number of meteor streams and the difficulty of 

 <letei'mining the radiant with any degree of precision. 



Mr. Denning does not, however, admit that an accidental coincidence 

 of radiant points of different streams is a sufficient explanation of the 

 phenomena he has observed. 



The zodiacal light. — Prof. Arthur Searle, who has made a special 

 study of the zodiacal light, finds that the permanence of the ordinary 

 western light, subject only to slight variations in the degree of visi- 

 bility, isconlirmed by the observations of the last 50 years at the Hanaud 

 Observatory. The zodiacal bands, which are said to form a prolong- 

 ation of the ordinary zodiacal light, were not seen, though stellar or 

 nebulous bands, one extending trom Aquila to the LMeiades, and the 

 second from Praisepe to Coma Berenices have been noticed and perhaps 

 ofter an exjdanation of the zodiacal bands. The Gegenschein, it is sug- 

 gested, may be due to a maximum of light reflected from the meteoric 

 matter scattered in the solar system. 



Tiie observations of Prof. C. Michi Smith, carried on at intervals 

 since 1875 indicate a periodic appearance of the line at wave-length 55S 

 in the zodiacal light si)ectrum ; a line differing but little in wavelength 

 from the auroral line (wave-length 550.7). 



PLANETS. 



A very laborious work is being carried on in the office of the Ameri- 

 can I*^[>hemeris, under the superintendence of Professor Newcomb — the 

 redetermination of the elements of all the larger planets. Professor 

 Newcomb's ])lan includes the re redu(!tion of the older ])lanetarv obser- 

 vations and the discussion of the later ones, with ai view of reducMug 

 them all to a uniform system. Another branch of this planetary work 

 is a determination of the mass of Jupiter from tiie motions of Poly- 

 hymnia, and a coniparison of Hansen's taides of the moon with observed 

 occultations since 1750. 



The first volume of this series of memt»irs upon the theories of the 

 major planets has ai)i)eared in the "Astronomical Pajiers," of the 

 AtnericMu epIuMueiis, being a new discussion of. Jupiter and Saturn by 

 Hill. He has determined the complete analytical expressions for the 



