3'K) Dr. J. Hancock's Observations on ' Heat Lightning] 



interruption for about an hour, and the flakes of snow which 

 then fell were the largest we ever saw, many being nearly an 

 inch in diameter. All the surrounding country was conse- 

 quently more or less covered with it, and upon the hills the 

 snow was of a very considerable depth in many parts. 



With the exception of a few fine days from the 22nd to the 

 25th, the month of April was exceedingly cold and chilly; 

 smart hail-showers occurred nearly on every alternate day, 

 and it was not until the 4th of May that the weather became 

 fine and seasonable. The summer that followed was upon 

 the whole fine, and the autumn one of the driest almost ever 

 recollected in this neighbourhood, so much so, that the navi- 

 gation of the canal in this vicinity is now, and has been for 

 some time past, considerably impeded for want of water. 



Carlisle, iNov. 10, 1833. 



LVII. On the Cause of the Appearance commonly termed Heat 

 Lightning, and on certain correlative Phenomena. By 

 J. Hancock, M.D* 



I BEG leave to notice an occurrence which is every year 

 more or less observable ; and although not peculiar to this 

 country (Demerara), it appears to merit special attention as 

 conducive, perhaps, not merely to speculative, but to practical 

 results. I allude to those luminous flashes or corruscations 

 of electric light which ate so remarkable on the coast of 

 Guiana, near the end of the dry season, (or before the com- 

 mencement of great rains, and not unfrequently in a sky free 

 from clouds,) darting from below the horizon either in solitary 

 flashes, or at times occupying an arc of it, from south-east to 

 ■west, almost in an incessant tremulous blaze, and rising up 

 the vault even to emulate the aurora borealis, as the latter 

 appears in winter, in North America, and other higher lati- 

 tudes. From the coast, these meteoric or electric flashes are 

 seen generally in a southerly direction, corresponding with 

 that of the Macosie mountains, or the great chain of Parime 

 (about 200 miles distant), and are most common in the months 

 of June and July. 



Similar flashes are seen also in the Orinoko near the en- 

 trance of the rainy season, which there begins in March or 

 April, proceeding, as it were, from the vast groups of granitic 

 mountains to the south-west of Angostura, whilst they are 

 rarely observed in the direction of the plains on the north, as 



* Communicated by the Author: a paper by whom, containing the 

 principal points here discussed, was read in 1826, at a Meeting of the Phi- 

 losophical Society of British Guiana, by the Rev. Stephen Isaacson, M.A., 



Secretary. 



