CLIMATE, he. 



The cold is, at these thnes, so piercing, that, not- 

 withstanding the motion of a tide that rises and falls 

 six feet, the Delaware, which is here a mile broad, 

 is frozen over in twenty-four hours ; and it conti- 

 Bues so obstructed for twenty, thirty, and, sometimes, 

 forty, days ; but at two or three different times : for, 

 every Winter, there are two or three thaws, parti- 

 cularly bet\yeen the thirtieth and fortieth days after 

 the solstice. 



In 1788, the thermometer fell, in one night, that 

 of the 4th of February, from 2 1-2 degrees below 

 the freezing point, to 16 1-4 degrees, and the river 

 was frozen hard by the evening following. 



In 1764, between ten o'clock at night, on the 31st 

 of December, and eight o'clock the morning follow- 

 ing, it was frozen so hard, that people could walk 

 across it. In this almost sudden conversion from a 

 fiuid to a solid, a smoke or vapour, says Dr. Rush, 

 was seen to rise from its surface, in such abundance, 

 that people assembled, in astonishment, to contem- 

 plate the phenomenon.* 



From these extremes we have a scale of variation, 

 for the middle states of 46 or 48 degrees. Dr. Rush 

 was one of the first who observed, that the climate of 

 Pekin was most analagous to it ; and on pursuing the 



pletely over, for many miles above and below Philadelphia, and 

 gained ulosed for about three weeks. 



* This frost smoke was explained in the account of Greenland, and 

 referred to the difference between the temperature of the air and wa- 

 .ter. The reader will find a set of original experiments on this curi- 

 ©us subject, in the Med, Repos. Hexade 1st, vol. iv, and Hexade 2dj 

 vol. ii, p. 444, and the principle upon which the app-^ai'^tiCe de|)eiicl[s> 

 reduced to a rule in nature. . - 



Q 2. 



