OBSERVATIONS UPON THE METEORS OF AUGUST. 267 



Notes were not kept while observing, nor was the precise time or track of 

 any one meteor preserved. But my efforts were immediately and continuously 

 made to locate a radiant point, should such be discoverable. I had no know- 

 ledge of the probable existence of such radiant, but took the hint from the his- 

 tory of the November meteors. 



A radiant region, if not a radiant point, was soon perceivable. The paths 

 traced back, excepting of about five meteors which were not conformable, passed 

 through, a circle, described from the sword clustre of Perseus as a centre, and 

 with a radius of 2°. Of this I sufficiently assured myself by tracing back the 

 lines of distant ones the moment after their disappearance, though unable to 

 find a concurrent j9om^ for all the tracks. In truth, these paths roould not meet 

 in a common point. The circle given, however, would have received nearly 

 every one of the sixty conformable meteors' paths. 



Considering our favourable position for observation, I think we saw every 

 visible meteor over one-third of the canopy. With this estimate, there were 

 about one hundred and eighty visible meteors per hour, or three per minute. 

 Add to this at least four invisible ones below the second magnitude for one that 

 reached it, (the fairness of which estimate will appear below,) and we should 

 have seven hundred and twenty meteors obscured by the moon, making about 

 nine hundred per hour for a clear moonless night. 



These observations, for 1838, were made at Rock Island, in the upper Mis- 

 sissippi, three miles above the mouth of Rock River; Latitude 41° 44' 7.5"; Lon- 

 gitude 13° 30' west from Washington, D. C. 



In 1839, circumstances were much more favourable for observation, there 

 being no moon, and the weather peculiarly clear. I copy from my travelling 

 diary. 



"St. Louis, Missouri, August 9, 1839. 



* * * A passenger from a coach which came in late, told me that he saw a 

 great number of meteors during the evening; and on being questioned for 

 their direction and locality, said, that all that he saw went from about the pole 

 star toward the Great Bear. Doubtless his position in the coach was such as 

 to expose only that field to his view; and all meteors observing the usual origin 

 for this shower, and passing near Polaris, must have travelled in that direction. 



"August 10th. 



* * * * This was the night for 

 the recurrence of the shower, and I was on the look-out. Before the twilight 



