120 
THE PHYSICAL GEOGRAPHY OF THE SEA. 
tions for two thousand eight hundred and twenty-nine years. He 
places his " meteorological pole" — pole of the winds— near lati- 
tude 84° north, longitude 105° west. The pole of maximum cold, 
by another school of philosophers. Sir David Brewster among 
them, has been placed in latitude 80° north, longitude 100° west ; 
and the magnetic pole, by still another school,* in latitude 73° S5' 
north, longitude 95° 39^ west. 
223. Neither of these poles is a point susceptible of definite 
and exact position. The polar calms are no more a point than 
the equatorial calms are a line ; and, considering that these poles 
are areas, not points, is it not a little curious that philosophers 
in different parts of the world, using different data, and following 
up investigation each through a separate and independent system 
of research, and each aiming at the solution of different problems, 
should nevertheless agree in assigning very nearly the same posi- 
tion to them all ? Are these three poles grouped together by 
chance, or by some physical cause ? By the latter, undoubtedly. 
Here, then, we have another of those gossamer-like clews, that 
sometimes seem almost palpable enough for the mind, in its hap- 
piest mood, to lay hold of, and follow up to the very portals of 
knowledge, where pausing to knock, we may boldly demand that 
the chambers of hidden things be thrown wide open, that we may 
see and understand the mysteries of the winds, the frost, and the 
trembling needle. ■ / 
224. In the polar calms there is 113) an ascent of air ; if an 
ascent, a diminution of pressure and an expansion ; and if expan- 
sion, a decrease of temperature. Therefore we have palpably 
enough a connecting link here between the polar calms and the 
polar place of maximum cold. Thus we establish a relation be- 
tween the pole of the winds and the pole of cold, with evident in- 
dications that there is also a physical connection between these and 
the magnetic pole. Here the outcroppings of the relation between 
magnetism and the circulation of the atmosphere again appear. 
May we not find in such evidence as this, threads, attenuated 
and almost air drawn though they be when taken singly and alone, 
yet nevertheless proving, when brought together, to have a con- 
sistency sufficient, with the lights of reason, to guide us as we seek 
to trace the wind in his circuits? The winds 106) approach 
* Gauss. 
