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222 _ Dr, Buacpsn’s Account of 
I FIND it, Sir, impoffible to guit this fubje&, without fome 
reflexions about the caufe, that canbe capable of producing’ 
fuch appearances < atan elevation above the earth, where, if the 
atmofphere, cannot abfolutely be faid to have oaateds it is cer= 
tainly to be confidered.as next to nothing... The firft idea which: 
fuggefted itfelf, that they were burning bedies projected with, 
fuch, a velocity, was quickly, abandoned, from the want ‘of 
any known power to raife them up to that great height, or, if 
there, to give them the required impetus; and the ingenuity” 
of Dr. Hattey foon furnifhed him with another, hypothefis,: 
in which he thought both thefe difficulties obviated. He fup-~ 
pofes there is no projection of a fingle body in the cafe; but that: 
a train'of combuftible vapours, accumulated in thofe lofty regions, 
is fuddenly fet,on fire, whence all the phanomena are produced 
by the fuccefiive inflammation *. But Dr. Hattey gives no jut 
explanation of the nature of-thefe. vapours, nor of-the manner | 
in which they -can, be raifed up through air fo extremely rare 3. 
nor, fuppofing themrfo raifed, does;yhe account for their regu-. 
lar arrangement in. a: ftraight and equable line of fuch prodi-} 
gious extent, or for their, continuing to burn in. fuch highly 
rarefied air. Indeed, it is very difficult to conceive, how va- 
pours could be prevented, in thofe regions where there is in a 
manner no preflure, from {preading out on all fides in confe-' 
quence of their natural elafticity, and inftantly, lofing that de-. 
gree of denfity which feems neceflary. for inflammation. | Be-, 
fides, it is to be expected, that fuch trains would fometimes, 
take fire in the middle, and {fo prefent the phenomenon of two 
meteors at the fame time, receding from. one, another ina ° 
direct line. 
Thefe difficulties have induced other philofophers to relin- 
quifh Dr. Hauxey’s hypothefis, and propofe, inftead of it, 
. * Phil, Tranf. vol, XXX. N° 360. 
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