0)1 tho Climate and Agriculture of the British Isles. 45 
and wliat is most important, as bcarin2; on our present inf|ulrj, 
is this, — that the air, amidst sleet and snow, and with a north-west 
wind, iiHis as warm as the sea ; and instead of being chilled by the 
storm, it was full 3° warmer than that of its mean for the 
month. 
The same ship, on the same voyage, in 10^ of latitude, further 
south on the American coast, found both the sea and the air 
below the freezing point. 
But if the high temperature of this northern part of the Atlantic 
leads us to the conclusion that its Avater must have been derived 
from a southern source, it is also obvious from the wide distribu- 
tion of its equitable warmth, that the thermometer does not 
detect any well-defined branch of the Gulf Stream flowing to the 
north-east. The full breadth of the stream is spread across the 
ocean, in a latitude above that where the south-west wind, as an 
anti-trade wind, comes to the surface, and blows with great regu- 
larity over a wide area : it passes across and presses on the 
whole width of the stream, and under its influence the heated 
water assumes the character of a drift current, and is thus car- 
ried into higher latitudes over a very wide portion of the Atlantic. 
Between the north of Scotland and Iceland, where the drifted 
waters are confined in a narrower space, it will be seen on the 
chart that in June traces of warm and colder Avater are found ; 
but along the coast of Norway it again assumes the character of 
a true ocean current, which, flowing into the Arctic Sea, keeps 
open water in the whale-fisher's bight, even up to Spitzbergen. 
If the Gulf Stream flowed through the middle of the North 
Atlantic, in the same manner as it does along the American 
roast in a narrow rapid and hot current, it would produce but 
little effect on our climate ; but drifted as it is by the returning 
trade-wind it communicates its heat to the wide sea from Ireland 
to the banks of Newfoundland, and fills the whole space between 
Norway and Iceland. It is from this greatly extended surface of 
heated water that our Avesterly Avinds derive their Avarmth and 
moisture. 
It is difficult to form an adequate conception of the amount 
of heat poured into the Atlantic by the Gulf Stream, and drifted 
TiortliAvard by the south-west Avinds. It is only by comparing 
the temperatures on land and on sea that Ave can arrive at any 
approximate result. In January month the temperature of the 
air on mid-ocean is about 53° when in the same latitude, east 
and Avest ; in the middle of both continents it is 5° beloAV zero : 
the difference of 58^ being equal to more than double the amount 
of heat Avhich exists in England between the months of January 
and July. Here then is a cause AA'hich produces a much greater 
influence on local Avinter climate than the sun ; and Ave begin to 
comprehend the extent and unfailing energy of that poAver Avhich 
