ON THE METEOROLOGY OF IRELAND. 



351 



VELOCITIES OF THE WIND CORRESPONDING TO THE TERMS OF THE 

 f SCALE (0-6). 



We see that the terms of the estimated scale correspond, nearly, 

 to an arithmetical progression of velocities, and not of pressures. 

 This fact has been already noticed by Dr. Eobinson. 



The common difference in this series, which is equal to its first 

 term, is obtained from the numbers of the third column by means 

 of the formula V = n Fi. The following are the deduced values : 

 I. V, = 12-0. IY. V, = 10-8. 



II. 12-5. Y. 10-2. 



III. 117. VI. 12-5. 



The mean of these values is Fi = 11*6. The calculated values of 

 F, contained in the last column of the foregoing Table, are, accord- 

 ingly, obtained from the formula 



r- 11*6x11; 



their agreement with the observed values is sufficient to establish 

 the assumed law. 



As a verification of the preceding result, I took also a tolerably 

 extended series of measurements of the pressures of the wind, corre- 

 sponding to the highest term of the scale, with Lind's anemometer. 

 Their mean gave 2'06 inches for the reading of the instrument 

 corresponding to that term ; and the corresponding pressure on one 

 square foot of surface, computed in the proportion of 5 -20 pounds 

 to the inch, is 10*7 pounds. Hence, the pressure belonging to the 

 unit of the scale is Pi = 0'30. The corresponding velocity is in- 

 ferred from the formula F 2 = 437 P. Its value is F, = 11 '5; a 

 result which agrees very closely with that already deduced from 

 Robinson's anemometer. 



The results hitherto given rest only on my own estimations ; it 

 remains to POP bow far tlvv accord with those <>f otln-r obsr-r. 



