346 CONJECTURES concernine 
volves in the fame time, fo that its centrifugal force muft 
be proportionably greater. ‘The diurnal motion of the 
earth tends to throw a vaft furplus of air on the equator, 
by which there is probably more air between the tropics 
than on the reft of the globe. But this is a matter of con- 
jeCture not to be perceived by any fort of preflure any more 
than by the barometer, for reafons obvious to thofe con- 
verfant in the nature and effect of the feveral principles. 
However it might not be amifs to obferve whether there 
be any difference in the height of the mercury before any 
of thefe ftorms. But to return. 
Although the air in the intert-ropical latitudes is in the 
general lighter than in the remote ones, yet when the 
upper air has obtained a paflage downward, it being vaft 
in quantity, and occupying great fpace, it will be long in 
accelerating and pafling down. The paflage is long, fo 
that it will gain a great deal of the force we find it has by 
the length of defcent. Neither will the middle region be 
difpofed to fhut up without a brifk wind in it, before the 
whole, even to remote regions, is difcharged through the 
large hiatus, as before mentioned and now repeated, to 
account for the duration and extent of thefe otherwife 
wonderful winds, with fuch unrelenting violence. 
Far different is the cafe of the high latitude tornados in 
their circumftances and their manner, although agreeing 
in their general nature. The centrifugal force here has 
extremely little effect, unlefs to caft the atmofphere to- 
ward the equator inftead of raifing or increafing its quan- 
tity over any given place on either fide. Befides there 
is the attraction of the fun, moon, and all the other pla- 
nets for ever within the tropics attraCting the atmofphere 
that way and leflening the height of the high latitude at- 
mofphere, which therefore may be fuppofed not a fourth 
fo high from the furface as that. 
Since then the atmofphere is vaftly lefs in height, and 
alfo much lefs in quantity than toward the line, the er 
mu 
