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viall^wire about its string, only to the height of twelve 

 or thirteen hundred feet, and at ati times it will pro- 

 duce fire, as I have found by frequent experience ; some- 

 times when the air was perfectly clear, without a cloud 

 in the hemisphere ; at other times, when it was thick and 

 hazy, and totally unfit for electrical operations below. 

 Now as this is the case at so small a height, and as we 

 find the effect still grows stronger in proportion as the 

 kite advances (for I have sometimes observed, that a 

 little blast of wind, suddenly raising it about a hundred 

 feet, has more than doubled the effect) what must it be 

 hi very great elevations? Indeed we may often judge of 

 it from the violence with which the clouds are agitated, 

 from the meteors formed above the region of the cjouds, 

 and particularly from the Aurora Borealis, which has 

 been ob erved to have much the same colour and appear- 

 ance as the matter that forms the tails of comets. 



There is a species of comets, says the same gentleman, 

 that have not tails : these are certainly bodies of a very 

 different nature from those with tails, to which indeed 

 they appear even to bear a much less resemblance thsui 

 they do to planets : and it is no small proof of the little 

 progress \ve have made in the knowledge of the universe 

 that they have not as yet been distinguished by a diifer- 

 ent name. 



This is the third kind of body that has been discover- 

 ed in our system, that all appear essentially different 

 from each other, that are probably regulated by differ- 

 ent laws, and intended for very different purposes. How 

 much will posterity, be astonished at our ignorance, and 

 wonder that this system should have existed for so 

 many thousand years, before we were in the least ac- 

 quainted with one half of it, or had even invented names 

 to distinguish its different members. 



I have no doubt, that in future ages the number of 

 the comets, the form of their orbits, and time of their 

 revolutions, will be as clearly demonstrated, as that of 

 the -p-.-n K>ts. It is our cQuntrynian Dr. HalJey, who has 



