176 ACCOUNT or a METEOR. 
great heights. 2dly. Their motions cannot be owing to 
gravity, for they defcend in all directions, and but feldom 
perpendicularly to the horizon. Befides, their velocities 
are much too great. ‘This meteor would not have fallen 
by the force of gravity, from the place where it firft ap- 
peared, to the earth, in lefs than two minutes of time; 
nor in lefs than ten feconds, if we fuppofe it impelled by 
gravity from the remoteft diftance. ‘They are neverthe- 
lefs affected by gravity in fome manner, for I cannot find 
that any one was ever obferved to afcend upwards in its. 
courfe. 
It is true that difficulties will likewife occur, if we fup- 
pofe them to be foreign bodies of fufficient denfity to pre- 
ferve fuch great degrees of velocity even in pafling through 
the atmofphere, for it may be afked why do they not fre-. 
quently ftrike the earth, buildings, &c. 
Perhaps they are generally, if not always, exploded in 
paffing through the air, fomething in the manner that 
filings of fteel are exploded in paffing through the flame 
of a candle. And at the fame time that they afford us 
occafion to admire the variety and immenfity of the Cre- 
ator’s works, they may perhaps produce fome important 
and neceflary effets in the atmofphere furrounding this 
globe, for the welfare of man and its other innumerable 
tribes of inhabitants. 
I am, dear fir, your affectionate friend, 
And very humble fervant, 
DAVID RITTENHOUSE. 
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