M. Bouvard on the influence of Wind, fyc. 



77 



The results obtained by the first of these formulae are given 

 in the last column of the preceding table. The errors in ex- 

 cess and defect are tolerably well balanced over the quadrant of 

 latitude. In 74°, where Captain Parry's observations were made, 

 the formula makes the daily variation only about the 600th 

 part of an English inch. 



Art. X. — On the Influence of Wind on the Height of the 

 Barometer. * By M. A. Bouvard, Director of the Royal 

 Observatory of Paris, &c. 



The direction of the wind exercises a very great influence on 

 the height of the mercury in the barometer. The winds from 

 the south cause it to fall, while those from the north make 

 it rise. This fact is well established by eleven years 1 ob- 

 servation at the Observatory. The following table contains 

 the mean height of the barometer reduced to the zero of tem- 

 perature for 9 h a. m. Noon, and 3 h p. m. The direction of the 

 wind was determined either by the direction of the clouds or 

 by that of the vanes placed on the Observatory. 



From these results it appears that the mean heights of the 

 barometer are lower during south winds, and that they increase 

 as the wind goes by the west from the south to the north, where 

 they reach their maximum. They afterwards diminish gradu- 

 ally in passing from the north to the south by the east. It is 



* This article forms one of the sections of M. Bouvard's Memoir already 

 referred to in p. 72. See this Journal, No. iv. p. 241. 



