16 THE FRESH-WATEK LOCHS OF SCOTLAND 
B 
Miller-Cassella maximum and minimum deep-sea thermometers 
(Buchanan's pattern) were also 
in use during the survey. In 
order to make a more profound 
study of temperature changes 
in a loch, an installation of 
electric thermometers, consist- 
ing of platinum resistance ther- 
mometers and a Callendar 
recorder, was set up at Fort 
Augustus, on Loch Ness. The 
recorder was placed in the 
boat-house of St Benedict's 
Abbey, and the thermometers 
were operated from the deck 
of a small yacht called the 
Rhoda, anchored in 300 feet 
of water and distant about 
300 yards from the boat-house ; 
a four-ply cable connected the 
recorder with the Rlioda. This 
same apparatus was later set 
up in Loch Garry by Mr E. M. 
Wedderburn in the spring of 
1908. A sunshine receiver 
which could be lowered to any 
depth in place of the platinum 
thermometers also formed part 
of the equipment. Experi- 
ments were also made with a 
thermophone outfit, purchased 
in America, for recording the 
temperature. 
Electrical Experiments. — 
Advantage was taken of Lake 
Survey facilities to make some 
experiments on a point of 
theoretical importance, viz. the 
ionisation of air when sur- 
rounded by thick layers of 
water. A charged electroscope 
Fig. 7. was immersed in Loch Ness at 
various depths, and the rate of leakage of the charge under these 
conditions was compared with the rate in ordinary circumstances. 
B 
