365 



XXI.— 0^2 the Irregular Oscillations of the Barometer 



at Manchester. 



By G. V. Vernon, F.R.A.S, 



Bead April 2nd, 1861. 



A PAPER having recently been read before the Society by 

 Mr. Baxendell, upon the values of the mean monthly and 

 annual amounts of the irregular oscillations of the baro- 

 meter, at various localities upon the globe, it was thought 

 that similar deductions from observations made at Man- 

 chester might be acceptable as additional data upon the 

 subject. 



All the observations given in this paper were made with 

 standard instruments. The barometer readings used were 

 made daily at eight a.m. 



In Table I. are given the total monthly amounts of the 

 oscillations and their number. 



The number of oscillations in each month may be 

 slightly in error, but never to the extent of an entire 

 oscillation : this arises from oscillations beginning in one 

 month and ending in another. As the number of oscilla- 

 tions could not be deduced for the entire year, it was not 

 thought necessary to estimate this number more closely. 



Table II. contains the mean daily oscillations for each 

 month, and has been formed by dividing the figures in 

 Table I. by the number of days in each month. 



The maximum amount of oscillation appears to take 

 place in January and the minimum in July, to which may 



SER. III. VOL. I. MM 



