METEORS OF AUGUST AND NOVEMBER. 125 



In the Journal of the Franklin Institute'" a letter addressed to Mr. Espy by 

 me is published, describing a singular telescopic appearance noticed while 

 watching for the emersion '^ of ^i Ceti from the dark limb of the moon, at forty 

 minutes past twelve, on the night of the 7th of August, 1833, with a five feet 

 Dollond, day eye-piece, power 30. The same event was seen by Mr. William 

 H. C. Riggs, with a three and a half feet Dollond, and also by his assistant, 

 Mr. Black, with the naked eye. Having observed the moon frequently for 

 many years with a telescope, in the city of Philadelphia, and never witnessed 

 any thing of the kind before nor since, I am inclined to ascribe the phenome- 

 non to a cluster of small meteors. At the time, I supposed the bodies seen to 

 be cinders from some neighbouring chimney. And it was not till after the 

 great display of November 12th of the same year that my attention was called, 

 to this appearance, and its date identified by the occultation. The small bodies 

 seen in the telescope traversing the moon's disc were semi-opake when on the 

 disc, and had a phosphorescent appearance; their discs were not more than 

 20" in diameter. They appeared to move downwards, all in perfectly parallel 

 directions. Sometimes several of them were seen traversing the moon's disc 

 at once. The time of passing through the field was, perhaps, 0M5, as nearly 

 as could be estimated. The downward motion observed at the time is consist- 

 ent with the tendency towards the convergent point for the August meteors. 

 The number seen could not have been less than fifty per minute in the field of 

 view of the telescope, which was about a degree. The phenomenon lasted 

 half an hour at least before the emersion; how long^ it continued afterwards I 

 do not know, as no farther observations were made. 



It must not, however, be forgotten that Professors Olmsted and Twining, 

 who, early in 1834, had " coincident ideas on the subject," were the first to 

 suggest the theory of annual periodicity of the November meteors, and to re- 

 vive the cosmical theory in connexion therewith. In their early efforts at form- 

 ing a theory, some opinions were advanced that have since been found untena- 

 ble. Of this class may be mentioned the supposed parallax of the radiant point 

 by the former giving for it a distance of about two thousand two hundred miles, 

 and that of a parallax in declination by the latter. This last conclusion, based 

 chiefly on the observations of Captain Parker in the Gulf of Mexico, in 1833, 

 is, perhaps, set aside by the more recent and careful observations of Mr. Fitch, 



^° Vol. XV., p. 234. «* Erroneously printed immersion oim Ceti in that Journal. 



VIII. — 2 G 



