476 
ARTICLE XVI. 
On the Periodical Variations in the Pressure of the Alinosphere 
in the Interior of Continents. By Prof. H. W. Dove. 
[Read before the Royal Academy of Berlin, October 1842. ] 
METEOROLOGICAL phenomena appear under such a va- 
riety of forms in the different parts of the earth, that the theo- 
ries advanced for their explanation bear more or less the stamp 
of the locality in which we are accustomed to observe. The 
annual periodical cycle is likewise of such great importance in 
this inquiry, that what the traveller gains by changing his place 
of observation is partly lost by not passing such a period with 
the atmosphere at the same locality. In avoiding therefore local 
errors he is apt to fall into temporal ones. Moreover, the peri- 
odical phenomenon becomes fully known only by its repetition ; 
and it is now agreed that the science is best promoted by sta- 
tionary sets of observations extending over large districts of the 
surface of the globe. 
On the coasts of England the attention of Saussure would not 
have been called to the importance of the ascending current, 
nor would Hadley have discovered the theory of the trade-winds 
in the valleys of Switzerland. If therefore we admit that moun- 
tainous countries have been the birth-place of meteorology, we 
must, on the other hand, confess that its progress was much 
promoted when it descended from the mountains into the plains. 
The substitution of Hutton’s rain theory for that of Deluc, the 
exchange of Saussure’s hygrological ideas for those of Dalton, 
are striking instances of this transition. It is owing to the 
dissimilar conceptions of the mountaineer and of the inhabitant 
of the plain having obtained their full estimation in the science, 
that the two fundamental principles of atmospheric processes, 
the motion of the air in vertical and horizontal direction, have 
obtained equal justice. Certainly, wherever we are, we can see 
but one of these operations in force; and even, as Espy has 
done, place an ascending current as leader at the head of a 
whirlwind ; but we have only to cast our eyes on one of Redfield 
and Reid’s maps of storms to be convinced that such an idea is 
by no means in accordance with nature. 
