THE COUESE OF STOEMS. 
143 
hagen, embracing the whole of Europe, and the North Atlantic 
Ocean, with parts of Asia, Africa, and America, and representing 
the chief meteorological elements at a given hour on every day 
of the year. 
Having once mastered the general laws of the wind, the 
observer of the weather is no longer coufined to a knowledge of 
what is going on at his own post of observation. He sees 
his mind’s eye the whole system, of which the weather at his 
own station forms a part. Like the comparative anatomist 
with his bone, he constructs an entire storm from a mere local 
fragment. If, for example, he notes a strong S.E. wind, he 
knows with as much certainty, as if he had telegraphic informa- 
tion of the fact, that a centre of barometric depression lies in the 
S.W. He has no positive means of ascertaining the distance of 
this centre, but if he sees his barometer falling fast, he knows 
that the centre is moving rapidly towards him. Should he 
observe the wind slowly veer from S.E, to S. and S.W., he will 
conclude that the centre of the storm is no longer coming 
towards him, but is passing at a considerable distance in the N. W. 
If the changes of wind, instead of being slow, are very rapid, 
he knows that the centre is passing at no great distance from 
him. If the wind, instead of veering in the ordinary direction, 
backs from S.E. to E. and N.E. (supposing him to observe in 
this locality), he infers that the centre is passing up the English 
Channel or across France. If, as sometimes happens, a dead 
calm prevails with a low barometer, he judges that he is in the 
centre of a cyclonic system. In the case of persistent gales such 
as we have lately experienced,^ oscillating between S.W. and 
W., he rightly pictures to himself a succession of deep depressions 
passing in the far North. In this way, so much additional 
interest is given to the observation of weather changes, as goes 
^ This paper was read March 4, 1881. 
