380 ANNUAL OF SCIENTIFIC DISCOVERY. 



begins, it goes on to the reduction of two rings. It was doubtful 

 whether the refraction would be sufficient to reach the earth. 



ON THE ZODIACAL LIGHT. 



PROF. D. OLMSTEAD, at the meeting of the American Association, 

 Albany, submitted the results of a series of observations on the zodiacal 

 light, made at Yale College during sis years, from 1833 to 1839. He 

 adverted to the general ignorance prevalent respecting this body, and 

 enumerated several causes which render continual observations diffi- 

 cult, such as the presence of clouds, of the moon, of Venus and 

 Jupiter, as also the low angle which the direction of the zodiacal light 

 makes with the horizon at certain seasons of the year. The Professor 

 next proceeded to inquire into the nature and constitution of the zodi- 

 acal light, as its length, its direction, its motions, and the material of 

 which it is constituted. It appears that the length, or elongation 

 from the sun, varies much at different seasons of the year, and not 

 only apparently, but really, being sometimes below 60 at one time, 

 and again reaching, in a few and rare instances, to 120. An elonga- 

 tion of 90 from the sun implies that it reaches to the earth's orbit, 

 and it must of course sometimes reach far beyond it. The direction 

 of the axis of this body was supposed, by Cassini and others, to be 

 that of the solar equator ; but the professor showed that that direction 

 varies at different times of the year, the vertex sometimes terminating 

 in the ecliptic itself. The motions of the zodiacal light are such as to 

 indicate a revolution around the sun, and this point was shown to be 

 accordant with the views of Laplace. The material of which this 

 body is constituted appears to have great analogies to that which 

 forms the tails of comets, included under the general appellation of 

 nebulous matter, being like that in its tenuity, transparency, shape, 

 and even shade of color. Finally, Professor 0. proceeded to the ques- 

 tion whether or not the zodiacal light is the origin of the periodical 

 meteors of November and August, particularly those of November. 

 He says that he does not assert, positively, that this is the body which 

 affords the meteoric showers. He had inferred, from all the facts of 

 the great meteoric shower of November 13th, 1833, independently of 

 all hypothesis, the existence of a nebulous body ; and now the ques- 

 tion is, is the body in question such as to identify it with that ? In 

 answer to this question, he, with great deference, offered the following 

 presumptions in favor of the idea that this is the body which affords 

 the periodical meteors. 1. It is a nebulous body. 2. It lies over the 

 earth's orbit in such a position that the earth might pass through or 

 near it at the time of the meteors of November. 3. Like tlie sup- 

 posed "nebulous body," it revolves about the sun. 4. Like that, its 

 periodic time must be commensurable with the earth's period. 5. 

 Finally, the meteors actually are seen to come from the visible extrem- 

 ities of the zodiacal light. 



LONGSTRETirS LUNAR FORMULA. 



PROF. PEIRCE, at the American Association, Albany, read a paper 

 entitled " An account of Longs treth's Lunar Formula." The Professor 



