apparent Velocity; or the upper Current going one 
Way, ^nd the lower another, and perhaps you will 
fee the Smoke going a Third. This fufficiently fhews, 
that there are different Currents in the Air. 
From all my little Obfervation I find, that the 
upper Current generally prevails. For though the 
under Currents from, fuppofe, the Eaft, or even 
North-eaft, be brisk at firft, and the brisker they are 
at firft, the longer they continue ; yet they die away 
by degrees, as their Strength fpends itfelf j the Air 
becomes near calm, and then the South- weft, which- 
before blowed aloft, defcends to the Earth, and 
commands the whole Sky. 
That the Diforders of the lower Air da not 
affett the Stream above, appears alfo from the Trade- 
wind palling over the very Continent, from the 
Eaftern to the Weftern Side of America .. I make no 
doubt but the high Hills of ‘Peru caufe a greater 
Variety of Winds and Weather, than we have here. 
Their Weftern Sea fhews, that the lower Part of the 
Trade-wind meets with great Obftru&ions in palling 
over the Continent. For, as c Dampier obferves, you 
do not meet with the true Trade-wind, till you are 
got 150 or 200 Leagues from Shore; and then it 
blows in its ufual manner. If all the Difturbance that 
the high Hills of Peru , faid to be the higheft in the 
World, give to the Trade-wind blowing over them, 
cannot intercept the upper Stream, which, after 
furmounting all thofe Heights, and the Diforder that 
their Cold occafions, ftoops down- again, till it comes 
to touch once more the Surface of the Ocean ; we 
may caftly fuppofe, that that Part of the Trade-wind, 
which is reflected from thefc Hills towards theNorth- 
caft, 
