( <5 1 ) 
be due Eafl at the Equator itfeif, according to Ex-, 
perience, by reafon of the Concourfe of both Cur- 
rents from the N. andS. where its Velocity will be 
at the rate of 2083 Miles in the Space of one Re- 
volution of the Earth or Natural Day, and above 
1 Mile and j in a Minute of Time ; which, is greater 
than the Velocity of the Wind is fuppofed to be in 
the greateft Storm, which according to Dr. T)erham'$ 
Obfervations, is not above 1 Mile in a Minute. 
But it is to be confidered, that before the Air from 
the Tropicks can arrive at the Equator, it muft 
have gained fome Motion Eaft ward from the Surface 
of the Earth or Sea, whereby its relative Motion 
will be diminifhed, and in leveral fucceffive Cir- 
culations, may be fuppofed to be reduced to the 
Strength it is found to be of. 
Thus I think the N.E. Winds on this Side of the 
Equator, and the S.E. on the other Side, are fully 
accounted for. The fame Principle as neceffarily 
extends to the Produ&ion of the Weft Trade-Winds 
without the Tropicks ; the Air rarefied by the Heat 
of the Sun about the Equatorial Parts, being re- 
moved to make room for the Air from the cooler 
Parts, muft rife upwards from the Earth, and as it 
is a Fluid, will then fpread itfeif abroad over the 
other Air, and fo its Motion in the upper Regions 
muft be to the N. and S. from the Equator. Being 
got up at a Diftance from the Surface of the Earth, 
it will foon lofe great Part of its Heat, and thereby 
acquire Denfity and Gravity fufficient to make it 
approach its Surface again, which may be fuppofed 
to be by that Time ’tis arrived at thofe Parts be- 
yond the Tropicks where the wefterly Winds are 
found. 
