298 Transactions.— Miscellaneous. 
14. The results of these experiments, which are corroborated by those 
of Mr. Robert Seott, Mr. Glaisher, and Mr. Charles Cator, appear almost 
-conclusively to dispose of the question—whether our present anemometrical 
returns be intercomparable for the purposes of climatology, by answering 
that question most decidedly in the negative. I may add that the observa- 
tions taken at the various New Zealand observatories during the past ten 
years exhibit such striking and inexplicable discrepancies as strongly to 
support this unfavourable view. 
15. We now arrive at the second point on which anemometry is sup- 
posed to furnish us with information, namely, the force ofthe wind in heavy 
gales. We seek to ascertain the dynamical force exerted by the horizontal 
movement of the air on a vertieal plane surface, such force to be expressed 
in pounds of pressure on each square foot ofthe said surface. Itis accepted 
as an axiom in meteorology that the velocity and pressure of the wind are 
eorrelative, and this correlation has been variously formulated. The 
formula now most generally accepted is that given by Sir Henry James, 
which is that the pressure in pounds on the square foot equals the square of 
the velocity in miles per hour multiplied by :005; or, sedent. algebrai- 
cally, if a be the velocity and « the required pressure, then —— a sa. 
16. From this formula it will be perceived that the EN of velocity 
to pressure proceeds with increasing velocities by a peculiar mode of pro- 
gression. The theory when investigated gives some rather remarkable 
results. For instance, at a velocity of 20 miles per hour, or what is 
considered a ** fresh ” breeze, the pressure is 2 pounds per square foot, but 
at a velocity of 40 miles the pressure is 8 pounds. So at 50 miles the 
pressure is 19-5 pounds; at 100 miles 50 pounds; at 150 miles, 112:5 
pounds. At 200 miles, could such a velocity be attained, the pressure 
would be 200 pounds; at 400 miles, 800 pounds; and at 1,000 miles, 
5,000 pounds. Thus by this formula when the velocity is doubled the 
pressure is quadrupled. Such at least is the accepted theory. 
17. It is true that other tables of relation between anemometric velocity 
and pressure have been constructed, but apparently they are founded 
merely on the concurrent records of Robinson's and Osler's anemometers, 
and not on any definite mathematical theory or investigation of the principle 
involved. For example, one author represents a force of 9 pounds as equal 
to a velocity of 49 miles, which he describes as ** a great storm." Another 
describes similarly a velocity of 74 miles, which he gives as equivalent to a 
pressure of 21 pounds. Ina third work a ** most violent hurricane" is repre- 
sented by a velocity of 107 miles, and a pressure of 46 pounds. A fourth 
deseribes a pressure and velocity of respectively 49 pounds and 110 miles, as 
“ a hurricane, tearing T trees and throwing down buildings"; while a fifth 
