28 
fluctuations in the barometer. These disturbing causes will, 
in any region, be much increased at the setting in of winter 
and the commencement of hard frost ; for at this crisis a large 
amount of latent heat will be liberated and will contribute its 
influence to disturb the equilibrium of the air. A similar 
crisis will occur at the end of winter on the breaking up of the 
frost, and will necessarily be attended with similar results. 
As the times of these crises appear to correspond in a remark- 
able manner with the times of maximum disturbance of the 
barometrical column, it seems but fair to infer that a relation 
exists between the causes here stated to be in operation, at 
the critical periods just named, and the periodical disturbance 
of the mercury in the barometer indicated by Mr. Baxendell’s 
“ dynamical curves.” The correctness of this inference, or 
the contrary, can only be established by future observation of 
phenomena, and the collection of facts, many of them of a 
kind seldom thought of hitherto as constituting elements for 
the solution of problems in meteorology. 
