THE BIRTH, LIFE, AND DEATH OF A STORM. 247 
principle which has been recognized in our science during the 
present generation, and its practical importance is daily forcing 
itself more and more into public notice with the development of 
weather telegraphy. It is usually known under the name of 
Buys Ballot’s Law, and is stated as follows : — 44 Stand with your 
back to the wind, and the barometer will be lower on your left 
hand than on your right.” 
The truth of this law is evident to anyone who looks at a 
weather chart, but the Dutch Professor, after whom it is named, 
though he justly claims the credit of having persistently advo- 
cated the acceptance of this relation of the wind to the distri- 
bution of pressure, was not by any means the first to discover it. 
The final result of all the inquiries into the question is that 
on the mean of all winds the angle between their direction and 
the tangent to the isobar at the place is about 20°. 
These principles of wind motion have a most important 
bearing on the theory of the motion of the air in hurricanes and 
typhoons. The old popular idea of these phenomena is that the 
air blew round and round the central calm in circles, so that 
any sailor caught in one of these storms could at once know that 
when he was hove-to, if he looked in the wind’s eye the centre 
bore eight points to the right in the northern hemisphere, and 
to the left in the southern ; or, what is the same thing, if he was 
scudding before the wind the centre would lie exactly on the 
starboard beam in the northern and on the port beam in the 
southern hemisphere. 
Modern meteorologists, however, almost with one voice, 
declare for a spirally incurving movement as the most probable 
behaviour of the wind, as would be indicated by the angle which 
its direction makes with the isobars as just explained ; but this 
view presents no novelty, for it was first stated about forty years 
ago, and Piddington, in his 44 Sailor’s Hornbook ” says that even 
Redfield, when propounding his 44 Law of Storms,” stated : — 
44 I have never been able to conceive that the wind in violent 
storms moved only in circles. On the contrary a vortical move- 
ment, approaching to that which may be seen in all lesser vortices, 
aerial or aqueous, appears to be an essential element of their 
violent and long-continued action, of their increased energy 
towards the centre of axis, and of the accompanying rain. In 
conformity with this view, the storm figure on my chart of the 
storms of 1830 was directed to be engraved in spiral or involute 
lines, but this point was yielded for the convenience of the 
engraver.” 
We see, therefore, that when we trace back to its origin the 
belief that any storms are really circular, we find that it was 
44 the convenience of an engraver,” which decided the question. 
It may be safely asserted that there does not exist for a single 
