
THE METEOROLOGY AND CLIMATE OF PLYMOUTH. 427 
from the Gulf Stream has been beautifully reasoned out by Croll 
and paraphrased by Knox Laughton thus: “The heat brought 
by the Gulf Stream into the North Atlantic has been fairly esti- 
mated as not less than one-fifth of the whole heat possessed by the 
surface water of that division of the ocean. Now Sir John 
Herschel, and other eminent writers, English and French, have 
estimated the temperature of space at 239° below zero. If with 
this we compare the existing temperature of the North Atlantic, 
which may be taken at 56° above zero, we find that the heat which 
it actually has corresponds to a temperature of 295°, the fifth part 
of which is 59° If then the fifth part of its heat, the heat 
derived from the Gulf Stream, were taken away from it, the surface 
water of the North Atlantic would have an average temperature of 
3° below Fahrenheit’s zero, or 35° below the freezing-point of fresh 
water.” (Croui’s Climate and Time, p. 35, et. seg.) Such a cal- 
culation may appear almost wild, but it errs if anything in allowing 
too much heat. Jam by no means sure that instead of 35° below 
freezing-point, I ought not to say 100°. 
Another way of considering the effect of the Gulf Stream leads 
to a result scarcely less startling. A quantity of water, which may 
-be roughly estimated at about five billions of cubic feet, is hourly 
poured through the Straits of Florida into the North Atlantic. 
This water has then an average temperature of not less than 65°, 
and after performing a circuit in the North Atlantic, returns to the 
tropics with an average temperature of not greater than 40°. It 
gives out to the air of the North Atlantic the heat corresponding 
to a difference in temperature of 25°. Now if you will remember 
that our standard measure of heat—the British thermal unit—is 
the quantity of heat necessary to raise the temperature of 1 lb. of 
water 1°, and that a cubic foot of water weighs about 64 lbs., you 
will see that the heat so thrown out every hour into the air of the 
North Atlantic is 
25 x 64 x 5,000,000,000,000 thermal units, 
Such a row of figures conveys little meaning. I will try to 
make it more intelligible. Every thermal unit, when converted 
into power, is capable of lifting a weight of 772 lbs. through a 
height of 1 foot; this is the law of equivalence experimentally 
established by Dr. Joule, of Manchester. Consequently the heat 
hourly dispersed from the waters of the Gulf Stream, if stored up 
