120 Philosophy of Storms. 
These opinions I esteem as of the utmost importance ; but that 
is a reason which makes me the rather desirous to decline enter- 
ing upon their consideration ; inasmuch as upon many of their 
connected points I have formed no decided notion, but am con- 
strained by ignorance and the contrast of facts, to hold my judg- 
ment as yet in suspense. It is indeed to me an annoying matter 
to find how many subjects there are in electrical science, on which 
if I were asked for an opinion, I should have to say I cannot 
tell—I do not know ; but, on the other hand, it is encouraging 
to think that these are they which if pursued industriously, ex- 
perimentally, and thoughtfully, will lead to new discoveries, 
Such a subject, for instance, occurs in the currents produced by 
dynamic induction, which you say it will be admitted do not 
require for their production intervening ponderable atoms. For 
my own part, I more than half incline to think they do require 
ese intervening particles, i.e. when any particles intervene, 
(1729, 1733, 1735.) But on this question, as on many othérs, 1 
have not yet made up my mind. Allow me therefore here to 
conclude my letter, and believe me to be, with the highest esteem 
and respect, my dear sir, your obliged and faithful servant, 
= M. Farapay. 
Royal Institution, April 18, 1840. 
Arr. XV.—Brief Synopsis of the Principles of James P. Esrv’s 
: Philosophy of Storms.* 5 
(Communicated for this Journal.) 
Wuen the air near the surface of the earth becomes more heat- 
ed or more highly charged with aqueous vapor, which is only 
five eighths of the specific gravity of atmospheric air, its equilib- 
rium is unstable, and up-moving columns or streams will be 
formed. tena 
As these columns rise, their upper parts will come under less 
pressure, and the air will therefore expand ; as it expands, it will 
grow colder about one degree and a quarter for every hundred 
yards of its ascent, as is demonstrated by experiments on the 
Nephelescope. 
Be meh a ei CE 
_ > * Copious facts going to establish the principles contained in this Synopsis, are 
