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Art. IV.— “O'/i the Fog of the Polar Regions, By Professor 
Hansteen. (Continued from page 93. of this Volume). 
Hudson’’s Bay and Straits, Baffin's Bay, and the sea around 
Greenland, are distinguished, in a remarkable manner, by a 
thick fog, which almost constantly prevails there. Captain 
Parry suffered much inconvenience from this fog, when he got 
into Lancaster Sound, and into the Straits discovered by him, 
which he calls Barrow**s Straits ; and the more on this account, 
that the compass ceased here to have any fixed direction, or, as 
the sailors say, it wandered. 
Lieutenant (now Captain) Franklin, too, if I remember right, 
experienced the same thing on his land expedition, along the 
northern coasts of America on the Polar Sea. Captain William 
Scoresby^s explanation of the origin of this fog seems very ad- 
missible, though there may be found other circumstances con- 
curring to the production of the same effect. A similar thick 
fog prevails likewise in the sea which surrounds Terra del Fuego. 
I have mentioned already, that Don Antonio de Ulloa says, 
in his letter to Mairan, that, in sailing round Cape Horn, 
he found only a few moments when he could obtain a slight 
glance of the sky. As the same fog is neither so thick nor so 
constant in other places of the same latitude, in Behring’s Straits 
for instance, or south from the Cape of Good Hope, it is not 
impossible that the streaming of the magnetic power, or of the 
polar lights, here, too, played their part. It is known by expe- 
rience, that, while these streamers are flowing, the sky has a 
tendency to become opake and misty. While the polar lights 
pass through the air, they must have the effect, in penetra- 
ting the watery vapours existing in it, im a transparent state, 
of taking from them their heat, and thereby rendering them 
opake. When a solid body passes over into a fluid, or a fluid 
body into a gaseous state, it acquires a greater quantity of heat ; 
and, in acquiring it, thus robs every surrounding body with which 
it comes in contact, of a part of what they contain. It is thus, 
in warm climates, they cool vessels by surrounding them with 
wet cloths ; so that the evaporation of the water in the form of 
steam, deprives the vessel of a great portion of its heat. In 
