aptcenieacsci ti 6 gM eds 
and the Velocity of the Wind. 361 
the United States, and the eastward motion in the North At- 
lantic is deflected south and north by the continent of Europe, 
while on the corresponding part of the coast of America the 
air is drawn away faster than it is supplied by the flow over 
the continent on account of the greater resistances on land than 
on sea, and the same occurs on the African coast in the torrid 
zone. Hence the deflected currents supply these deficiencies 
the middle of the former gyration, and of low barometer in the 
middle of the latter. The effect of these gyrations is indicated 
by the isobars drawn on the British Admiralty charts, on which 
several of these isobars, drawn to tenths of an inch of the bar- 
ometer, always return into themselves. If we suppose these 
isobars to be 500 miles apart at any place, on the parallel of 30°, 
the value of G would be 0-02 of an inch, and with this value of 
G, putting /=30°, we get from (1) v=8 miles nearly for the 
stead of 8,300,000, G expresses the gradient of sea-level due to 
he earth’s rotation. The southern part 
of the North Atlantic is supposed to make a gyration in about 
three years, on account of the more complete deflections of the 
continents in this case similar to those of the atmosphere. 
This, at the distance of 1,500 miles from the center of gyration, 
would give v=—0-35 of a mile, v being negative, since the gyra- 
tions are from left to right. With this value of v, putting 
seci=1, we get from (1) with the new denominator, G=—058 
of a foot for the change of sea level in 100 miles on the parallel 
of 30°. The value of G being negative shows that the sea- 
