of Rain at different Heights, 123 



- beautiful, when fwimming in fuch a veflel. 

 But thefc obfcrvations, which mufl: have been 

 made by numberlefs fpeftators, in a long 

 fuccelTion of years, were regarded as foiitary 

 fads; and it was not till the thirteenth century, 

 that fpeftacles were conftrucled, in confequence, 

 probably, of the experiments made by the 

 Arabian philofopher Alhazen, and our juflly ce- 

 lebrated countryman Roger Bacon. Ytt thoufrh 

 magnifying glafles came then into general ufe, 

 iand muft have been daily handled by artifls and 

 others, three hundred years elapfed before it 

 occurred to any one to put them together. To 

 as to form a telefcope. The colleftion of 

 watery vapours in the air, the figures of cloudsj 

 and the defcent of rain, could pafs in no ao'e 

 unnoticed by mankind, and have long been 

 the fubjeds of attentive inveftigation. Yet it 

 is a very recent difcovery, which we owe to 

 the fagacity of a moft ingenious phyfician and 

 philofopher, that a manifcfb difference fubfifts 

 \n the quantity of rain which falls, at different 

 heights, over the fame fpot of ground. 



A comparifon having been made between the 

 rain which fell in two places, in London, about 

 a mile diftant, it was found that the quantity 

 in one of them conftantly exceeded that in the 

 other, not only every month, but almoft every 

 time it rained. The apparatus ufed was very 

 exad i and this unexpsded variation did not 



appear 



