36 



REPORT — 1841. 



Upon the ivorking of WhewelVs Anemometer at Plymouth during the 

 past year. By W. S. Harris, Esq., F.R.S. 



My last Report on this instrument contained an account of cei'tain im- 

 provements in the mechanism and mode of fixing found by experience neces- 

 sary to its perfect employment. I have now the satisfaction of bringing under 

 the notice of the Physical Section a series of observations, continued for a 

 whole year ; from which has been laid down, by the inventor's method, a gra- 

 phic delineation or type of the wind during this time, and extending from 

 July 184'0 to July 1841*. It will be seen by this chart now before us, that 

 we have, to a great extent, realized Mr. Whewell's happy thought, namely, 

 that of obtaining a sort of type of the winds for a given place, so as eventu- 

 ally to arrive at the general annual movement of the air. The mean result 

 of the observations now before us agrees nearly with that arrived at by the 

 observations made by Mr. Southwood, with the same instrument, and printed 

 in the Eighth Report of the Association. It shows in this place (Plymouth) 

 an annual movement of the air from the S.S.E. toward the N.N.W. nearly. 

 It is not a little interesting to observe the daily march of the wind, as indi- 

 cated by the daily register of the instrument. We find, for example, certain 

 tourbillons or great disturbances occurring here and there, which seem to 

 interfere with what might probably, in more settled latitudes, be a constant 

 and regular movement of the air, as in the trade winds ; yet, upon the whole, 

 the progress of such a regular current is traceable, notwithstanding these in- 

 terferences ; and the movement of the air is found to be by this chart from the 

 southerly to the northerly points of the compass. It does not seem requisite, 

 for our present purpose, to attempt more than a very summary generaliza- 

 tion ; without therefore obtaining, by a strictly geometrical method, the re- 

 sultant magnitude and direction for each month, and from these again the 

 resultant magnitude and direction of the Avhole, as done in my former Report, 

 it will perhaps suffice to pass a line immediately through the whole series of 

 types, in such way as to obtain by the eye alone the final resultant. Such a 

 line will evidently pass from the S.S.E. to the N.N.W. points of the compass, 

 or very nearly. If now we associate this fact with the result obtained from 



* The delineation liere referred to was exhibited in the Section-room, in a frame 12 feet 

 high by 6 feet wide. 



