Pressure of Aqueous Vapour. 



415 



The pressure is constant in the winter quartei- from 7** p.m. till 6'' a.m. ; and in the mean for the year the 

 pressure is nearly constant from 11'' a.m. till S"" p.m. 



The mean tension of aqueous vapour for the year occurs at 7*" 50™ a.m. 



S"" 30m P.M. 



The interval between the two epochs of mean tension is 12'' 40"" 



TABLE XII. — Hourly Means of the Pressure of Aqueous Vapour for each Month in 1844, 

 as deduced from Tables II. and VIII. 



TABLE XIII. — Hourly Means of the Pressure of Aqueous Vapour for each Astronomical yuartei-, 



and for the Year 1844. 



