ON THE ANEMOMETERS OP PLYMOUTH. 241 



Report on the Working of Whewell and Osier's Anemometers at Ply- 

 mouth, for the years 1841, 1842, 184'^. 

 By W. Snow Harris, Esq., F.R.S., ^c. 



There is no department of meteorology in so unsatisfactory a state as that 

 relating to the general course and velocity of the wind, especially in high 

 latitudes; for although many talented persons have given their attention oc- 

 casionally to this subject, and a variety of instruments for measuring the 

 force and velocity of the wind have been suggested, yet no series of observa- 

 tions conducted upon any definite or correct view of the great periodical and 

 other movements of the air, and embracing the question in all its generality, 

 has, so far as I can learn, been ever fairly carried out, so that we yet require 

 careful investigations by means of simultaneous observation, and with instru- 

 ments well-adapted to the purpose, in order to appreciate with anything like 

 accuracy the phaenomena of winds and the laws of atmospheric circulation. 



Meteorology, as a predictive science, is certainly very defective ; almost 

 every change in the state and condition of the air is generally considered 

 quite an affair of chance, yet such is not really the case ; the philosopher 

 knows nothing of chance, and is well assured that every atmospheric varia- 

 tion is the result of unerring laws. 



The laws of the periodical movements, and general circulation of the air 

 about our globe, demand very special attention, as being intimately as- 

 sociated with future atmospheric changes. It is not improbable, from the 

 great regularity of the winds in latitudes but little subject to capricious va- 

 riations, that even in higher latitudes a similar regularity may upon the whole 

 become apparent, in eliminating by a sufficient number of observations the 

 forces which disturb the general course of the winds in these latitudes. 



The great defect of the partial methods hitherto pursued in observing and 

 recording the winds, has been a want of due attention to their force and ve- 

 locity; the direction, together with the time which any particular wind 

 blows, being the only elements usually considered. We have it is true one 

 or two useful tables by Rous, Hutton and others, expressing the common 

 designation of certain winds and the velocity due to certain pressures, but 

 these do not appear to have been employed in obtaining any general meteo- 

 rological deduction, such as the mean direction and rate of motion of the air 

 in a particular place for any given period, and which it is most important to 

 determine. To arrive at this, however, we require a correct register of the 

 direction and velocity or some other element from which the velocity may 

 be determined. Professor Whewell has well explained this in his valuable 

 paper in the Cambridge Philosophical Transactions, vol. iv. Indeed it is 

 quite evident, that more air may be transferred over a given place in one day 

 by a wind blowing with great force in a certain direction, than would move 

 over the same place in a week by the gentle breezes of a wind blowing in 

 an opposite one, and hence any inquiry which does not embrace this essen- 

 tial principle in anemometry, cannot be productive of correct results. 

 Ksemptz, with a view to the generalization of the winds of different latitudes, 

 has, in the absence of all record of their velocity, supposed them all equal in 

 force, and takes their duration as the measure of their value, considered as 

 so many distinct forces. 



It was with the intention of obtaining a more perfect investigation of 

 this question, that the British Association confided to my care the anemo- 

 meters designed by the Rev. Professor Whewell and Mr. Osier of Birming- 

 ham, both of which were so theoretically constructed as either to give at 

 once the integral force of the wind, that is to say, the velocity conjointly 



1 844. R 



