75 
PHYSICAL AND MATHEMATICAL SECTION. 
October 14th, 1873. 
E. W. Binney, F.R.S., F.G.S., in the Chair. 
Mr. Samuel Broughton was elected Treasurer of the Sec- 
tion, in place of the late Mr. Thomas Garrick. 
“Mean Monthly Barometric Headings at Old Trafford, 
Manchester, from 1849 to 1872,” by G. V. Vernon, F.B.A.S., 
F.M.S. 
Having a tolerably complete register of barometric read- 
ings, and knowing of no published normal values for any 
station in or near Manchester, I have reduced and tabulated 
the monthly means for the period above named. 
The barometer with which the observations were made 
was a standard by Negretti and Zambra,. No. 266, and 
which had been compared at Greenwich. 
All the observations have been corrected for capillarity 
and index error to reduce them to the Greenwich standard, 
and then reduced to 32° F. 
In the earlier part of the series I have unfortunately some 
months deficient, but in the latter part of the series I have 
been able to fill up the gaps by the use of the very careful 
series of observations made at Eccles by my friend Thomas 
Mackereth, Esq., F.B.A.S., by applying corrections deter- 
mined by comparing the months in which the observations 
were simultaneous. 
I found that the two series of observations were nearly 
identical after allowing for difference of level. 
The mean annual pressure for the entire series was 29 '780 
inches, which, corrected for an altitude of 123 feet above 
the mean sea level, and assuming the mean annual tempei'a- 
