ae 
Botany and Zoology. 413 
only about 3° in the whole, or three-fourths of a degree for every 
100 fathoms; and this body of water has a temperature so much 
above sie isotherm of the northern stations, at which the observa- 
the reduction being 5°-4, or above 2° ag 100 fathoms ; while be- 
tween 750 and 1000 fathoms it amounts to 3°°1 , bringing down the 
temperature at the latter depth to an etae of 38°°6. Beneath 
this there is still a slow progressive reduction with increase of 
depth, the temperature falling a little more than 2° between 1000 
and 2435 fathoms ; so that at the last-named depth, the greatest at 
its temperat as been reduced by the diffusion through it of 
frigid water from a Polar source. e — supposition best ac- 
cords with the gradual épranonra of rature 
The saison es ert recently taki by Commander 
: d Lieutenant Johnson, R. N., at various points 
the Europ cae eae and American continents, that its only com- 
munication with the North Atlantic basin—besides the circuitous 
passages leading into Hudson’s and Baffin’s Bays—is the space 
which intervenes between the eastern coast of Greenland and the 
ninsula, t — 
flow 8 tt the iiss pantions “of tk is ae at the or 
xpanse. 
tween Greenland arr Iceland, the wept is such as to mona st ee a free 
a , t a ; ecti | - . b: . 
ment of frigid water at a “rat xcsotiog + A similar barrier 
1s not merely lateau on aren the British Islands 
rt, ut alo by the ed of i the North sea; the shallowness of 
