77 
Experiments upon Heat. 
extraordinary coldness is vulgarly supposed to be communicated 
to the air by the snow ; but this is an erroneous opinion ; for 
these winds are in general much colder than the snow itself. 
They retain their coldness, because the snow prevents them 
from being warmed at the expence of the earth ; and this is a 
striking proof of the use of the snows in preserving the heat of 
the earth during the winter, in cold latitudes. 
It is remarkable that these winds seldom blow from the 
poles directly towards the equator, but from the land towards 
the sea. Upon the eastern coast of North America the cold 
winds come from the north-west ; but upon the western coast 
of Europe, they blow from the north-east. 
That they should blow towards those parts where they can 
most easily acquire the heat they are in search of, is not ex- 
traordinary ; and that they should gradually cease and die away, 
upon being warmed by a contact with the waters of the ocean, 
is likewise agreeable to the nature and causes of their motion ; 
and if I might be allowed a conjecture respecting the principal 
use of the seas, or the reason why the proportion of water upon 
the surface of our globe is so great, compared to that of the 
land, it is to maintain a more equal temperature in the diffe- 
rent climates, by heating or cooling the winds which at cer- 
tain periods blow from the great continents. 
That cold winds actually grow much milder upon passing 
over the sea, and that hot winds are refreshed by a contact with 
its waters, is very certain ; and it is equally certain that the 
winds from the ocean are, in all climates, much more tempe- 
rate than those which blow from the land. 
In the islands of Great Britain and Ireland, there is not the 
least doubt but the great mildness of the climate is entirely 
