692 THE POPULAR SCIENCE MONTHLY. 



having to estimate the direction and rate of motion of every storm the 

 instant it shows itself in their neighborhood, are in the position of 

 astronomers expected to assign the path of a comet from the first 

 glimpse they get of it through a break in a cloud a problem which all 

 will allow to be impossible of solution. Accordingly, great interest 

 attaches to the attempts made from time to time to lay down princi- 

 ples for forecasting the motion of the disturbance. 



I have already stated that, as a general rule, the cyclones move 

 round the anticyclones ; but this principle requires for its application 

 to storm-warning purposes, access to charts embracing a very consider- 

 able extent of the earth's surface. These are very difficult for English- 

 men to obtain, as our own daily charts are very limited in area, and 

 frequently do not exhibit even the whole extent of a single cyclonic 

 depression, much less its relation to the distribution of pressure all 

 about it. For those, however, who can consult such charts it is pos- 

 sible, so to speak, to take their stand at a higher point of view and sur- 

 vey the conditions prevailing, say over Europe, on any given day. 



If the amount of change in the pressure or of rise and fall of the 

 barometer during the preceding night be plotted every morning on such 

 a chart, it is found that the path of the system for the day does not lie 

 directly toward the region where the greatest fall has occurred during 

 the night, but is regulated to a certain extent by the direction of the 

 line drawn from the point of greatest fall to that of greatest rise. 



Another theory of storm-motion, strongly held by those who attrib- 

 ute all our storms to condensation of vapor, is that the track of the de- 

 pression is always directed toward the region where the air is dampest. 

 This principle, like that just noticed, can hai'dly be turned to account 

 in this country for our own practical benefit, inasmuch as the whole of 

 these islands appear to be almost equally damp, owing to the proximity 

 of most of our telegraphic reporting stations to the sea. 



Other suggestions have been made in various quarters, with the 

 view of throwing light on this very important subject ; but we can 

 not say that the results have met with general acceptance, and the mat- 

 ter urgently demands further study. 



I must now come to the final portion of my theme the death of a 

 storm ; and on this subject, unfortunately, I have very little to say. 

 As we have not been able to produce evidence of the birth of a storm, 

 so have we never been lucky enough to find any one who was in at the 

 death. In fact, some French meteorologists have hazarded the state- 

 ment that storms can travel all round the world until at last they travel 

 off it. 



Storms have been traced from the Pacific coast of North America 

 across the Atlantic ; but these instances are necessarily rare, and, as 

 far as European experience goes, no storm arriving from the Atlantic 

 ever travels far into Russia. This fact is, of course, very much in fa- 

 vor of the condensation theory of storm generation, which has already 



