88 
NATURE NOTES 
observations have therefore been subjected at Greenwich to a 
“smoothing” process, after which July 15 (64-35°) still remains 
the hottest day, though the i6th is practically as warm. Jan- 
uary 10 and II (37-7°) now rank as the coldest days of the year. 
The first maximum temperature of 70° or upwards in March 
during the half-century takes place on the 24th (70-9°), in 1871 ; 
and it will be seen that this almost immediately follows the 
commencement of Spring. It is interesting to note that on the 
same day, in 1879, the maximum is only 33-4°, tending to show 
that Winter endeavours to extend his realm up to about this 
date. The i6th, in 1845, is the time of the latest occurrence in 
the early part of the year of a maximum temperature of 32° 
or below {2j‘6°). This date is almost on the boundary between 
Winter and Spring. Apropos of the remark that March is in 
some places very little warmer than January, it may be stated 
that the mean temperature of March ii is a mere trifle higher 
than that of January 31 (40-5°)! Even after “smoothing,” the 
difference is but 1-4°. The latest instances of a maximum tem- 
perature of 70° or upwards happening in the Autumn are 71-6° 
on October 15, 1861, and 71-4° on the same day in 1862. A 
maximum of 67-3°, however, occurs as late as November 8 in 
1847. 
From March 22 to April 4 (inclusive) the Greenwich mean 
temperature rises as much as 5-8° — from 41-4° to 47‘2°. It is 
evident, therefore, that the pulse of Spring commences to beat 
vigorously at about the time of the Vernal Equinox. Soon after 
the beginning of the Autumn there is a corresponding fall of 
the mean temperature. It amounts to 6° — from 56-3° on 
September 28 to 50-3° on October 13 (inclusive). 
It has been stated that when the mean temperature has risen 
to 42°, vegetation generally begins to increase. In this connec- 
tion it is well to observe that the date in March when this mean 
temperature is not followed by a lower one is the 23rd (42-7°), 
the day nearly corresponding with the first of Spring. After 
November 26 (42-5°) all mean temperatures for a time are below 
42°, except that of December 6 (42-1°), and the alleged stoppage 
in the growth of general vegetation happens, it will be seen, 
soon after the beginning of Winter. 
The latest date of the occurrence of a minimum temperature 
of 32° or below in May is the 24th (1867), and this is only just 
after the end of the Spring. In September the earliest date is 
the 27th (1885), and this almost coincides with the commence- 
ment of the Autumn. The earliest instance of a maximum tem- 
perature of 32° or below at this season is on November i6th in 
1887 (29-2°). This day is almost on the line between Autumn 
and Winter. A maximum of 80° or upwards I see has never 
occurred in the fifty-year period after September 22 (80-5° in 
1848), except (8i-o°) on (Jctober 4, 1859. The 22nd marks 
almost exactly the end of the Summer. The first record of 
a maximum temperature of 80° or upwards in Spring is on 
