46 On the Temperature of the Sea, and its Injiuence 
reverses the normal position of the lines of equal temperature, 
and twists them from east to Avest into north and south curves. 
Our winter heat comes not from the south, but from the west. 
But again : the average temperature in January of 50° north 
latitude, over sea and land, is about 16° ; on the same parallel in 
the middle of the Atlantic it is then 53° ; and on our western 
shores 43° ; showing an increase of temperature over the sea of 
37°, due to the influence of the Gulf Stream. Assuming that 
the outlines of sea and land remained the same, with no warm 
current of water flowing northwards from the torrid zone, then 
the January temperature of the south-west of England would 
be as cold as that of the south-east of Iceland ; and on Scotland 
Avould fall the cold of the extreme north of Europe. 
The effect of Sea Temperature on the Air. — It has been said that 
the Gulf Stream does not really produce such an effect on our 
climate as has been attributed to it ; that in fact the winter heat 
over western Europe is the result of the south-west winds. Again, 
it has been urged that the latent heat released by the condensa- 
tion of moisture on our western coast-line is the cause of our 
abnormal climate. But even admitting the full effects which 
these causes produce, we have only to carry the inquiry one 
step further back, to show that the warmth of the wind and the 
excess of vapour from the air are both derived from the heated 
surface of the ocean. 
It has also been intimated that the south-west wind, returning 
as an upper current from the torrid zone, falls on the surface of 
the North Atlantic, and imparts its warmth to the water, and 
thus raises and sustains the high temperature of the sea around 
our coasts. This opinion raises a distinct issue. Does the wind 
impart its heat to the sea, or does the sea warm the wind ? The 
generally-received opinion, that the air which rests on the surface 
of the sea partakes of its temperature, appears to receive con- 
firmation from the character of the climate of coast-lines, — from 
the nature of the regular alternation of sea and land breezes ; 
and a comparison of the amount of heat in the sea and air of 
the Atlantic tends also to confirm this opinion. An examina- 
tion of four voyages across the Atlantic, from longitude 10° to 
40° west, gives the following results as the mean of all the 
observations taken, about the 50th parallel of latitude on each 
voyage :— 
Temperature of 
Water. Air. 
January 15 to 22, 1849 52 .... 49 
1 to G, 1850 54-5 .... 54-G 
7 to 11, 1851 50-G .... 49-6 
19 to 30, 1852 (the storm) .. 56-5 .... 55-7 
Means 53-4 .... 52-2 
