246 
between Norway and Iceland. The same temperature, 0.9? C., 
coog say 
Hooor 
rooot 
THREE ORUISES OF THE “ BLAKE." 
S sow 
u"uoDlvno3a 
К e 
тэп B 
occurs under the equator at a depth 
of about 2,300 fathoms, while 5° 
C. is found at a depth of 300 
fathoms. As early as 1859 the 
Coast Survey had recorded in the 
Straits of Florida a temperature 
of 40° F. (4.4° C.) at a depth of 
300 fathoms, while at the surface 
the temperature was 80° Е. (26.7° 
C.) Beyond 1,000 fathoms the 
temperature diminishes very slowly. 
The “Challenger” also found a 
temperature somewhat below zero 
off the Rio de la Plata, at а depth 
of about 2,900 fathoms. 
The temperature of the oceanic 
basin depends upon the depth, the 
latitude, the currents, and the 
seasons; that of mediterraneans 
(land-locked seas) is controlled by 
other causes, which will be more 
fully discussed when we come to 
treat of the temperature of the 
Caribbean and of the Gulf of Mex- 
ico. The constants are the depths 
and latitude, while the disturbing 
elements are represented by the 
varying atmospheric and oceanic 
currents and the seasons. The 
effects of seasonal differences of 
temperature do not extend to great 
depths, yet act with sufficient 
power greatly to modify the force 
1 Dr. J. J. Wild has given in “Thalassa ” 
an excellent diagram, showing at a glance the 
general relations of the temperature in the 
liquid envelopes to the earth’s crust. It is 
here reproduced (Fig. 171), slightly modified. 
