182 Meteoric Shower of Kovemher, 1836. 



" Although these inductions are very evident to myself, and seem 

 to be necessarily derived from the facts, and from the laws of attrac- 

 tion, I only offer them with extreme diffidence, because I know how 

 easy it is to be deceived in such matters by the most probable anal- 

 ogies, which we cannot verify by rigorous calculations. It is scarcely 

 necessary for me to state, that all the circumstances of position, di- 

 rection, and periodicity, peculiar to the meteors of the 13tb of No- 

 vember have been collected and made known by Mr. Olmsted, (of 

 America,) in a very comprehensive and highly interesting work. He 

 attributes this phenomenon to the existence of a great meteoric cloud, 

 circulating round the Sun in an orbit inclined about 7 degrees tow- 

 ards the ecliptic. This is also very nearly the inclination of the solar 

 equator and nebula. In order that this cloud may come in collision 

 with the Earth on the 13ih of November, he places it at the same 

 distance from the Sun in its ascending node ; but only wishing the 

 collision to take place at this point, he gives it a revolution of six 

 months, in an ellipse, the aphelion of which answers to the node of 

 the 13th of November. This peculiarity, besides being improbable, 

 does not appear to me to be necessary to the hypothesis ; for every 

 ellipse sufficiently different from the terrestrial ellipse by its flattened 

 form, or the actual position of its perihelion, would fulfil the same 

 conditions.* Mr. Olmsted, in the addition to his first work, publish- 

 ed in 1836, says, that he also thought the phenomenon of 1833 might 

 have some affinity with the zodiacal light; and, as a sign of this 

 connection, he makes the curious remark, that in 1833 the zodiacal 

 light was unusually apparent, much more so than in 1834 or 1835. 

 But he infers, that the meteoric cloud may be precisely this very 

 light, more apparent in November because seen in its aphelion at a 

 lesser distance from the Earth, whilst six months afterwards, about 

 the 10th of May, being come back to the same node, and the Earth 

 being on the other side of the Sun, we see it in opposition at a greater 

 distance, and consequently under a smaller apparent diameter. Now 

 these purely optical variations, which must take place in every posi- 

 tion of the Earth, according to the laws of perspective, for a finite 



* Professor Olmsted does not consider the period of six months as an essential 

 part of his theory, but admits that it may be a year. Thus, in the last number of 

 this Journal, page 394, he observes as follows : — " In the present state of our knowl- 

 edge on this subject, I regard it as a point open for inquiry, whether it will best 

 accord with all the phenomena of shooting stars, to give to the meteoric body a 

 period of nearly one year, or of half a year." 



