3 THE GULF STREAM. 901 
The earlier work of the Coast Survey in its investigations into the 
structure of the Gulf Stream (1545 to 1860) consisted in making see- 
tions across the stream, from the Straits of Bemini as far north as the 
latitude of Nantucket. From the studies of Craven, Maftitt, Bache, 
and Davis were developed the so-called cold and warm bands, believed at 
that time to be the principal characteristic of the Gulf Stream. The 
accompanying map (Fig. 5), published in 1860 by the Coast Survey, 
will serve to illustrate the structure of the Gulf Stream as it was then 
understood; namely, as a succession of belts composed of warm north- 
erly currents flowing side by side with a cold southerly current, or of 
a cold southerly current which had found its way under the warmer 
northerly currents. These alternating belts had no definite position, 
the size of the colder bands and warmer belts being dependent, the one 
upon the force of the arctic current, the other upon that of the trepical 
2650 fins 
Bermad 
Sandy Hook 
1240 fms. 
f azyoo 
7 2850 
2600 
Fic. 6.--Challenger observations. 
current, increased in breadth and volume beyond the Bahamas by the 
whole of the warm belt of surface equatorial water, which is deflected 
northward by the Windward Islands, instead of forcing its way through 
the passage between the Windward Islands, the Mona and Windward 
passages, and the Old Bahama Passage.* 
*Great as is undoubtedly the effect of the Gulf Stream proper (Fig. 6) in increas- 
ing the temperature of the water in northern latitudes subject to its influence, we 
must not forget to add to it that of the greater mass of heated water which is forced 
north, and finds its way to the northernmost shores of Siberia, losing in its passage 
the heat it has accumulated within the tropies. So that, while we can not say that 
the Gulf Stream has disappeared, and has been replaced off the Banks of Newfound- 
land by the equatorial drift, neither can we attribute to the Atlantic drift alone the 
masses of warm water found in the basin of the northern part of the North Atlantic. 
(See Figs. 1 and 6.) 
