53 Proceedings of the American Philosophical Society. 



The attention of observers, Mr. Walker remarked, was first called to 

 the August period, by duetelet, in 1836 ; and in 1837, precise observa- 

 tions were made at the Berlin and Breslaw observatories. These were 

 reduced by the formulae given by Mr. Erman, in No. 385 of Schumacher's 

 Astronomische Nachrichten, and have determined with precision the com- 

 mon point of convergence for August 10th, 1S37. In the same year Mr, 

 Forshey, then Professor of Mathematics in Jefferson College, Mississippi, 

 noticed, about the middle of August, a great number of meteors, originating 

 chiefly about the region of Cassiopeia. It appears, also, that Mr. Schaef- 

 fer,* of New York, searching for a radiant point on the 9th of August, 

 1837, placed the same near the north pole. Mr. Herrick,t at New Haven, 

 who had previously invited attention to this period, in the United States, 

 on the same evening, found this point farther north than in the November 

 shower ; but determined nothing farther. In 1838, these meteors were 

 seen by Mr. Kreil, at the Milan Observatory, but no radiant point was de- 

 duced. In the United States, however, Professor Forshey, from sixty five 

 meteors seen in one hour, August 9th, at Rock Island, Iowa, concluded 

 the radiant to be situate within a circle of 2° radius, centering in the 

 sword cluster of Perseus. In 1839, Mr. Herrick,| with others, at New 

 Haven, found the radiant point to be near the sword cluster, on the 9th 

 and 10th, being nearly stationary. On the 10th, at 13h. they found it to 

 be near Persei. 



Mr. Forshey, in 1839, August 10th and Uth, at St. Louis, again no- 

 ticed the radiant point in the same position as in 1838. But the position 

 of this point, or rather the point of convergence of their apparent paths, 

 has been computed with great precision from the observations at Berlin, 

 August 9th, 10th, and 11th, and at KOnigsberg, August 10th and 11th. 

 The mode of observation adopted at the European observatories has been 

 to mark on a map the points of origin and disappearance, and, subse- 

 quently, to compute, by Mr. Erman's formulae, the common point of con- 

 vergence. As the August meteors become visible chiefly in the northern 

 zones, it was thought that greater precision would be attained by noting, 

 besides the point of origin and disappearance, also the part of Perseus or 

 Cassiopeia, intersected by the apparent path of the conformable meteors, 

 traced backwards through one of these constellations. The following ta- 

 ble gives the point of convergence thus deduced from three separate 

 groups of observations at Philadelphia, together with the position of this 

 point, as determined at the European observatories, and the probable er- 

 ror of a single result, and of the final result computed in the usual man- 

 ner. The general agreement in the positions will be seen. The small- 

 ness of the probable errors of the Philadelphia results is attributed to the 



* Silliman's Journal, Vol. xxxiii, p. 134. t Ibid. pp. 176 and 359. 



\ Ibid. Vol. XXXVII, p. 328. 



