172  &E. B. Hunt on the Dynamics of Ocean Currents, 
the poles, which by the trade winds and continents is determined 
along a single line of debouche. This gives a discharge with 
less frictional resistance than a direct meridional outflow would 
encounter, as this would involve a polar set. for the entire ocean 
f; . 
surface. fn 
Accepting the well-determined trade-winds and the eq torial 
current as certain facts, we shall find that the vast surface shee 
of water which has a westerly set under the trades, haying ac 
quired a very considerable velocity, becomes the representative 
of a vast amount of living force. When by impact against west 
north or south, it still retains the greater portion of its livia 
. force, and will continue to do so until this is wholly expe 
in overcoming resistances. now we bear in mind. that the 
wide equatorial sheet is by this deflection consolidated into @ 
compact current of deep section, and also that the resistance | 
mile is proportionate to the length of the line of frictional resi 
ance in a cross section, we shall see that the currents 12 
towards the poles with their forward impulse almost unabated, 
and with the resistances greatly reduced.. We ought, therefore, 
to expect that the inertia of this vast moving mass would sume 
to carry it on with a mean velocity, slowly abating, to the polar 
regions. So soon as the progress of the current gives it an 
increasing latitude, the effect of the diminishing pal Is 
giving an eastward trend would show itself; and, combined with 
the forward projectile motion of the mass of waters, would de 
rmine the route of the current, governed, of course, b solid 
Opposing masses of continents, islands, and shoals. gat 
Reaching the artic neighborhood, this current would fall in 
with the tendency to restore to the equatorial region the wales 
withdrawn by outflow, which thus leave a deficienc) of stati¢ 
Mass in that region. Its forward force not yet expendet wo 
bring it into the equatorial flow only after a long arch sweep. 
Then bordered in by the eastern occean coasts, it circles on 1 | 
the equatorial belt, there to start the repetition of its CO¥™ 
either directly, or by proxy, if, entering at.great depth eae | 
only to lift higher portions above the normal leve We bet : 
a a ceoiunte cireuit in which the water whirls ape a 
Timary impulse derived in the equatorial regions, 80° 4. 
due to heating and the direct dats Bee of the trade-wih'™ 
The primary order of circulation is in two currents, the uppet 
running polewards, and the under from the poles to the equa" 
4s order is entirely modified by the action of the trades, * tion : 
comes essentially a horizontal circulation, the propelling § ee 
es 
of these perennial winds, cons ith the outflowing (Me 
c ds, piring with the outio : 
1ty to ine an immense ere ae of which the Ii 
force imparted in the equatorial region suffices to catty ©?" 
circuit in full and enduring activity. 
