of Atmospherical Phenomena. 33 
should have been excited when the atmospheric pressure was not 
found to diminish from winter to summer, with increasing heat. 
Vhen, by the labors of Prinsep more particularly, the phenom- 
ena of the tropical atmosphere in Hindostan became more known, 
there was seen to be a great difference between the barometric 
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Was atl immediate consequence of the periodical change of wind, 
i.e. of the monsoons. This erroneous view was completely re- 
futed when the barometric relations at the Siberian stations be- 
came known; for it was then found, that north of the Himalaya 
(which in the supposed hypothesis must have formed the limit of 
the phenomenon), the annual barometric variation was exhibited 
on a large scale, and over a region so extensive, that the shores 
of the Icy Sea itself could hardly be assumed as its boundary. 
A greatly diminished atmospheric pressure taking place in summer 
over the whole continent of Asia must produce an influx from all 
surrounding parts; aud thus we have west winds in Europe, north 
winds in the Icy Sea, east winds on the east coasts of Asia, an 
south winds in India. The monsoon itself becomes, as we see, 
In this point of view only a secondary or subordinate phenomenon. 
I have endeavored to establish the reality of the above phe- 
nomenon and its climatological bearings in several memoirs ; and 
I must refer for the numerical values to Poggendorff’s Annalen, 
vol. lviii, p. 177; vol. Ixxvii, p. 309; and to the Berichte of the 
Berlin Academy, 1852, p. 285. Iwill here embody the results in 
distinet propositions, in order to show, in connexion therewith, 
the importance of the bearings of the Hobarton observations. 
At all stations of observation in the torrid and temperate 
Soons than beyond it, having in that region rather the character 
of a flattened summit or table-land, the elasticity continuing 
Nearly the same throughout the period of the rainy monsoon. 
Near the equator the convex curve of the northern hemisphere 
ecomes, first flattened, and then gradually transformed into the 
Concave curve of the southern hemisphere. In the Atlantic this 
transition takes place in a rather more northerly parallel. In re- 
gard to the magnitude of the annual variation, the following rule 
Szconp Srnizs, Vol. XIX, No. 55.—Jan., 1855. 5 
