50 PHILOSOPHY OF STORMS. 



western sun, in a perfectly clear sky. This cloud seemed 

 nearly stationary for some time in its upper snowy part, 

 while the scattering clouds in its lower parts were seen to 

 rush under it, towards the south east, with great velocity. 

 The principal cloud moved slowly and majestically towards 

 the E. S. E. ; the sun's rays gradually climbing up this 

 mountain of snow, fourteen minutes after he set, his last 

 beams ceased to illuminate its summit. 



The altitude of this summit being taken by a sextant, was 

 found to be nine and a half degrees. The line which bound- 

 ed light and darkness as it rose up the sides of this columnar 

 cloud, was well defined, the western horizon being entirely 

 free from clouds, so that I think I could not be mistaken one 

 quarter of a minute in the time when the sun's rays ceased 

 to shine on the top of the cloud. Calculating from these 

 data, I find the cloud reached to the amazing height of ten 

 miles, and that it travelled E. S. E. with a velocity of about 

 forty-five miles an hour." 



A much more violent storm than this had occurred at 

 Wilmington, (Del.) about twenty-eight miles southwest of 

 Philadelphia, two days before this, as appears from Dr. 

 Gibbon's Journal. He says it commenced raining with a 

 thunder gust, at five o'clock in the morning, and poured 

 down in torrents till half past seven, when it ceased. In 

 this short time, two and half hours, five and one-tenth 

 inches of water fell. This rain, he says, did not extend 

 further than ten or fifteen miles from Wilmington, in any 

 direction, except, perhaps, in an easterly course, in New 

 Jersey. 



On that evening, my journal says, " The upper clouds 

 from the W. S. W. were tinged with pink, thirty-one 

 minutes after seven o'clock, mean time." These clouds, be- 

 ing in the zenith, must have been the astonishing height of 

 fourteen miles, if no allowance is made for the refraction of 

 light. 



