204 
VICISSITUDES OF MEAN DAILY TEMPERATURE 
THROUGHOUT THE YEAR, &C. 
By E. G. Aldridge, F.G.S., F.R. Met. Soc. 
HOUGH the Reduction of the Greenwich Meteoro- 
logical Observations, 1841-1890, Part HI., has long 
been published, I am not aware that any attempt on 
‘ a fairly large scale has been made to extract from 
it information which may be both useful and entertaining. I 
venture now to offer, for the use of the readers of your periodi- 
cal, some interesting statements which I have prepared from a 
study of the figures given in Tables IX., XL, and XII. of the 
volume above referred to. In Table XII. the temperatures are 
those derived by taking the mean of the daily maximum and 
daily minimum, 1841-1890. Tables IX. and XI. contain the 
mean daily maximum and the mean daily minimum tem- 
peratures after they have undergone the “ smoothing ” pro- 
cess which was found desirable at Greenwich Observatory in 
order to lessen the many irregularities existing in Table 
XII., notwithstanding that observations were made during 
the lengthy period of fifty years. From these two tables I 
prepared a third, showing the mean daily temperature. Only 
one place of decimals was used; and when the figure in the 
second place was “ 5,” it was rejected. The “smoothed ” values 
represent, I suppose, what would have been the result if obser- 
vations had been taken since (let us say) the time of IMagna 
Charta, or during some other very extended period, the climate, 
of course, remaining unchanged. It will be understood that the 
temperatures are in degrees Fahrenheit, and that all of them, 
unless otherwise stated, are mean temperatures. The 29th of 
February is not dealt with. 
“Unsmoothed” Values. “Smoothed” \ alues. 
Table XII. From Tables IX. and XI. 
January. 
Tlie month opens with a mean 
of 37'9°- The 3rd, 4th, and 5th 
show an increase of about 05'°. 
On the 6th the temperature falls to 
377°, and remains near that point 
till the 1 2th, when the value is 
37'o° — the lowest of the whole year. 
The next day shows a rise of o'9° ; 
and on the 19th the mean is 38‘8°. 
On the 2 1 St, however, the tempera- 
ture falls to 37'3°, and is nearly as 
low as that of the 12th. On the 
22nd it is 38 'o°, and on the 23rd 
387° ; and there is now a some- 
what interrupted increase till the 
The month opens with a tem- 
perature of 38'2’. The differences 
from day to day arc small ; and 
there is a practically continuous 
drop to 377° on the loth and nth 
(the coldest days). After these, 
there is an almost unbroken rise to 
39'8° on the 31st (the warmest 
day). From the 19th to the 22nd 
a slight incidence of cold is indi- 
cated. Range during the month, 
