METEOROLOGY. 



291 



The mean daily range for eacli month is exhibited in the subjoined 

 table, which embodies the two last years' observations with the ther- 

 mometrograph. 



For 1856-'57. 



£ o 



Mean of all highest readings by day 

 Mean of all lowost readings by night 

 Mean daily mensual range 



57.38 



13.66 



63.5668.22 71.30 



1 



1 

 47.9150.01 



15.65il8.21jl7.95 



79,20 



78.95 81.03 



53.35 



58.88^58.8864.69 

 20.3222.0716.34 



78.99 57.75 



55.45 49.86 



I 



23.54:17. 



59.41 



67.29 



16.96 



Dividing the year into its meteorological seasons, the mean daily 

 ,nge will be as follows : 



Spring, (February, March and April) 15°. 84 



Summer, (May, June, July, August, and September) 19°. 64 



Autumn, (October and November) 16°. 83 



"Winter, (December and January) 12°. 18 



Reverting to the table of monthly and annual means we find the 

 respective mean temperature of the seasons to be as follows : For the 

 spring months, mean 55°. 31, the mean maximum being 71°. 20, and the 

 mean minimum 42°. 13 ; for the summer, mean 70°. 19, and the mean 

 maxima and minima 92°. 50 and 55°. 11, respectively ; for the autumn, 

 mean 58°. 47, and mean maxima and minima 78°. 20 and 44.°00, re- 

 spectively ; in the two winter months the mean is 45°. 94, the mean 

 maxima 0°.90j and the mean minima 29°. 70 



Thus it is demonstrated that there is a mean difference between 

 winter and spring of 9°, 35 ; between spring and summer of 14°. 88 ; 

 between summer and autumn of 11°. 72 ; and between autumn and 

 winter of 12°. 53. The difference of the means of the hottest and 

 coldest months between summer and winter is also shown to be 

 24°. 25, and the extreme variation_, or the difference between the mean 

 maxima of the former and the mean minima of the latter, 41°. 50. 



It will be noticed that in our division of the seasons we have, in 

 accordance with the phenomena observed, defined February as the 

 first of the three spring months, and appropriated five months to 

 summer, and only two to autumn, and two to winter. Indeed, the 

 dormant season is of so short duration that the tropical division into 

 the wet and dry seasons would perhaps be more appropriate. The 

 whole period of sensible winter is far from being a complete season of 

 suspension of vegetation. During the period we have assigned to it 

 many forms of vegetable life are still active ; particularly the roots of 

 grasses and winter grains. The lowest mean daily temperature 

 belonging to this period is seldom below 40°. Although the ther- 

 mometer has been known to fall as low as 33° as late as the 10th of 

 February, still the leafing process generally commences during the 

 first week of February and is completed at a temperature not much 



