OF TEMPERATURE AT TORONTO IN CANADA. 
149 
rature is passed through about 8^ 31 ™a.m., and 7‘' 44 "'p.m., making intervals of 
Ilh J 3 m and 12*^ 47“. The hours from 9 p.m. to 7 a.m. inclusive are throughout the 
year colder than the mean temperature of the day; those from 10 a.m. to 7 p-m. are 
throughout the year warmer than the mean temperature of the day ; 8 and 9 a.m., 
and 8 p.m., are sometimes warmer and sometimes colder than the mean temperature ; 
8 a.m. is colder except for about three weeks in July, and 9 a.m. is warmer except 
from November 20 to March 11 ; 8 p.m. is colder from the middle of March till late 
in November, and either coincides with the mean temperature, or is slightly warmer 
during the remainder of the year. 
The hours of highest and lowest temperature on every fifth day of the year, and 
the amount by which the temperature at those hours exceeds or falls short of the 
mean temperature of the day, may be examined in detail in Table III. From the third 
week of September until April, 2 p.m. is the warmest hour, with the exception of some 
days in January and February, when 3 p.m. is warmer ; from April to the middle of 
May, and again from the end of July to the middle of September, 3 p.m. is the warmest 
hour; and from the middle of May to the middle of July, 4 p.m. The coldest hour 
from the latter part of April to the end of June, and again from the end of October 
to late in November, is 4 a.m, ; from the middle of July to the middle of Oetober, 
in January, and for a short time in the middle of April, it is 5 a.m. ; from the latter 
end of February to early in April it is 6 a.m. ; and generally in December and 
February 7 a.m. Jlie range from the minimum to the maximum in the day is greatest 
in July (18°'2), and least at the end of December (5°'2). The daily range has but 
one maximum in the year, which is in July ; not as at Prague, where June and July 
have a less range than the months immediately preceding and following them, and 
where consequently there are two maxima; a phenomenon attributed to the greater 
prevalence of clouds in June and July. 
It may be desirable to add a few words on the assistance to observers of tables 
which furnish corrections to the mean temperature of the day for every hour of every 
day in the year, such as Table III. Besides their direct use at the station itself, 
they have a useful bearing, within a reasonable distance from the station, on the 
selection of observation hours in the many cases in which it may not be possible to 
observe at hourly or two-hourly intervals, by affording a ready means of estimating 
the amount of error to which a deduction from any limited combination of hours is 
subject. If we desire for example to seek the observation hours within the command 
of a single observer, which may give the best approximation to the mean temperature 
of the day, and to that of the month, and of the year, as well as to the climatic 
difference (/. e. the difference between the hottest and the coldest months), we find, 
that of homonymous hours, the best pairs at Toronto are 9^ — 9^ and 10'' — 10'', 10'' — 10'' 
being the better of the two; but that 8'' — 8'', which is a combination frequently 
adopted by observers, does not suit so well at Toronto as either 9'' — 9'' or 10'' — 10'', 
The average errors in the different months, when the temperature is inferred from 
MDCCCLIII. 
X 
