DAILY RANGES OF TEMPERATURE. 
r is found that animal life is best preserved wben the temperature 
f each season is that of its average, and when the range of tempe- 
iture is also that of the average, and that sickness and death follow 
jay great departure from these averages. 
The occasional destruction of shrubs and fruit-trees by the cold of 
S inter is very distressing and very annoying;, and this sometimes takes 
lace when the mean temperature of the aiP is the same as the plant 
is previously endured without injury; but the mean temperature of a 
i ariod does not represent the actual temperature to which the plant 
Us been subjected. The mean temperature may be based upon a 
| mge of temperature corresponding to the average, or it may be from 
jie much smaller or much larger than the average ; and in the latter 
; ise the plant is subjected to the injurious effect of alternate very high 
Ud very low temperatures, and in winter time this would imply a 
] iriod, and perhaps a long one, in which the temperature was below 
h° Fahr, 
i It is very important that the agriculturist and out-door horticulturist 
l .ould know the ranges of temperature to which plants are exposed in 
j e open air. This variation of temperature differs day by day and 
I onth by month ; and it is only after a long series of observations 
I I at we are able to determine the average daily range in every season, 
le readings of the maximum and minimum thermometers have been 
’ ken continuously at Chiswick since 1826, and the difference between 
1 ese values gives the range of temperature on each day throughout 
He period comprised between the years 1826—1869. Collecting these 
mth by month and arranging them in parallel columns for different 
i ars, we have at one opening the ranges of temperature on every day 
| roughout that month for the whole forty-four years, and thus Tables 
NX. to XLI. were formed. 
