130 On the Causes, Laws, &c. 
windy weather. This is strikingly verified by the above observa- 
tions, with the addition of rain. The Doctor further observes, 
«¢ When they occur, I have noticed that all meteors which happen 
on the same evening leave the aforesaid long white tails behind 
them.” In these observations we do not agree on this point. 
We have in former observations frequently seen a few meteors 
with and several others without trains of light the same evening; 
and yet they have generally appeared of the same size, height, 
and colour, and nearly in the same tract. If the properties of 
the atmosphere about East Grinstead are different from those 
about Gosport, that might account for it: but this is not probable 
in so short a distance. Certainly we have a greater exposure of 
water around us here, and a greater quantity must necessarily be 
carried up by evaporation than in the more inland parts of the 
country: but whether this would alter the chemical properties of 
the atmosphere, so as to give a different aspect to our view of 
meteors in motion, appears questionable. We have no other 
object in view by these remarks, than to establish the facts of ob- 
servations on these and other atmospheric phenomena, which 
have been made here occasionally with the greatest caution ; and 
therefore think, with all due respect to Dr. Forster, who appears 
to be an acute observer, that the above quoted assertion does not 
always hold good throughout whole evenings observations, even 
when wane-clouds, or small and thin cirrostrative nubecule a- 
bound ; nor yet when the sky ,is apparently clear. Ifthe Doctor 
can conveniently devote a few clear nights when meteors prevail, 
we have no doubt that he will see the propriety of these remarks. 
XXIX. A Refutation of Mr.Heravatn’s Mathematical In- 
quiry into the Causes, Laws, Sc. of Heat, Gases, Gravita- 
tion, Fc. By Mr.'THomas TREDGOLD. 
** We are to admit no more causes of natural things than such as are both 
true, and sufficient to explain their appearances.” 
Newton. Rules of Reasoning. 
To Dr. Tilloch. 
Sir, — Ix some of the late Numbers of the Annals of Philoso- 
phy* there has appeared an attempt to account for the phzno- 
mena which are commonly ascribed to an attractive force. 
Such attempts are naturally to be expected, and will continue 
to be made so long as men feel desirous of comprehending the 
nature of the material world. It is also equally natural to oppose 
* Annals of Philosophy for April, May and June 1821. 
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