572 
Proceedings of the Royal Society 
[May 18, 1872. — Circumstances having delayed the publication 
of the Society’s Proceedings, I take this opportunity of adding the 
result of recent and conclusive observations. These were made on 
10th April and 6th May, as near as I could to the place of the 
observations described above. 
April 10. — The weather on this occasion was very fine and 
favourable for my purpose. During the whole winter period after 
November 18th, the date of the last observations, the weather 
had been remarkably open. The mean temperature of the atmo- 
sphere for the five intervening months, as kindly calculated for me 
by Mr Buchan, Secretary of the Meteorological Society, from 
observations at Balloch Castle, at the southern end of the loch, 
was 1 0, 4 higher than the average for the same months for thirteen 
previous years.* Consequently, the same influence of the winter 
season on the temperature of deep waters cannot be expected as in 
ordinary winters, or in a hard winter, such as the preceding one of 
1870-71. 
When I made my observations, about 3 p.m. on 10th April, the 
temperature of the air on land was 55° ; and on the water, one mile 
from the shore whence the wind blew, it was 53° in the boat, 
scarcely 2 feet above the surface of the lake. The following tem- 
peratures were obtained, at various depths in the same place : — 
Surface, . 
43°-0 
150 feet, . 
42°T 
50 feet, . 
42°*6 
200 „ . . 
42°-0 
75 „ . 
42°2 
594 ,, bottom, 
42°*0 
100 „ . 
42°-2 
These observations were made with Casella’s protected thermo- 
meter. The thermometer in Adie’s cistern, for bringing up water 
from the bottom, also stood at 42° when brought up to the surface, 
the temperature of the upper warmer stratum being much too low 
to affect the cistern in its passage. 
May 6. — Between 10th April and this date the weather varied 
* In tbe course of his calculations Mr Buchan arrived at the interesting 
fact that the average mean temperature of the air during the six cold 
months of these years, at the level of the lake’s surface, was 41°*7 from No- 
vember 18 to April 10, cr very nearly that of the deep substratum . — See sub- 
sequently, for his observat. ons , the later Proceedings of the Society. 
