792 
Proceedings of the Iioyal Society 
beginning of winter, or on the 18th November; and that this deep 
water temperature probably remains constantly at, or very near, 
42° 0. 
Sir Robert asked me for a statement of the temperature of the 
air at Loch Lomond from 18th November 1871 to 10th April 
1872, or during the time that the cold stratum of water of the 
uniform temperature of 42 o, 0 had increased about 100 feet in 
thickness. This I have prepared from the observations made at 
Balloch Castle, by Mr David Hill, the observer of the Scottish 
Meteorological Society at that place, Balloch Castle is at the foot 
of the loch, and 72 feet above its surface. The table showed the 
mean temperature of each day during the time,—the mean of the 
maximum and minimum temperatures of each day being assumed 
as the mean temperature of that day. Of this table an abstract is 
given below, from which it appears that the mean temperature, 
from 
November 18 to 30 
was 
38°'0, or 2°*5 below the 
average 
December 
1 „ 31 
55 
39°*4, „ 0°-4 
55 
January 
1 „ 31 
>5 
40 o, 8, ,, 2 0, 3 above 
55 
February 
1 „ 29 
55 
CO 
o 
CO 
o. 
CO*' 
o 
CO 
:> 
55 
March 
1 „ 31 
5 5 
43°-6, „ 2°*1 
55 
55 
April 
1 „ 10 
55 
45°*6, „ l°-4 
55 
55 
The average temperature of the 145 days was 4L7, which l°-4 
above the average of past years. 
Taking the observed mean temperature of each day for Edin¬ 
burgh as calculated by the late Principal Forbes,* and applying to 
these the differences observed between Balloch Castle and Edin¬ 
burgh, the normal temperature of each day at Balloch Castle was 
calculated. In this way the divergence of the temperature of each 
of the 145 days from its normal was ascertained. The amount for 
each day was given in a table,—temperatures above the average 
being given in red ink, under the average in blue. An abstract of 
this table is given below, from which it appears that there were 
four cold, and four mild periods, as under :— 
* Trans, of the Society, vol. xxii. p. 351. 
