398 THE DEPTHS OF THE SEA. [CHAP. VIII. 
the red stream widening out and becoming paler over 
the general surface of the water till it reaches the 
opposite edge, and very shortly the rapidly heighten- 
ing colour of a band along the opposite wall indicates 
an accumulation of the coloured water where its 
current is arrested. If we now dip the hand into 
the water of the centre of the bath, a warm bracelet 
merely encircles the wrist; while at the end of the 
bath opposite the warm influx, the hot water, though 
considerably mixed, envelopes the whole hand. 
The North Atlantic forms a basin closed to the 
northward. Into the corner of this basin, as into a 
bath,—with a north-easterly direction given to it by 
its initial velocity, as if the supply pipe of the bath 
were turned so as to give the hot water a definite 
impulse,—this enormous flood is poured, day and 
night, winter and summer. When the basin is full— 
and not till then—overcoming its northern impulse, 
the surplus water turns southwards in a southern 
eddy, so that there is a certain tendency for the hot 
water to accumulate in the northern basin, to ‘ bank 
down’? along the north-eastern coasts. 
It is scarcely necessary to say that for every unit 
of water which enters the basin of the North 
Atlantic, and which is not evaporated, an equivalent 
must return. As cold water can gravitate into the 
deeper parts of the ocean from all directions, it is 
only under peculiar circumstances that any move- 
ment having the character of a current is induced ; 
1 Ocean Currents. An Address delivered to the Royal United 
Service Institution June 15th, 1871. By J. K. Laughton, M.A., 
Naval Instructor at the Royal Naval College. (From the Journal of 
the Institution, vol. xv.) 
