416 
BATHYMETRICAL SURVEY OF 
of soundings per square mile of surface is 128. The aggregate volume 
of water contained in the lochs is estimated at 280,923 millions of 
cubic feet, or less than 2 cubic miles. The area drained by these lochs 
is about 690 square miles, or twenty times the area of the lochs. 
Notes on the Temperature of the Water* in Loch Ness. 
By E. M. Wedderburn, w.s., ll.b. 
Regular temperature observations in Loch Ness were begun at Fort 
Augustus in July, 1903, at the same time as the first limnograph to be 
used in Scotland was erected. At first the temperature observations 
were subsidiary to the other observations made in the loch, but gradually 
their importance increased until the investigation of lake temperatures 
became one of the principal studies of members of the Lake Survey 
stationed on Loch Ness. The observations were originally made from 
a rowing boat by means of the Pullar and Lucas sounding machines and 
deep-sea reversing thermometers. An endeavour was made to take the 
observations at regular hours in as nearly as possible the same positions 
in the loch from day to day, but in stormy weather the keeping of the 
same position during lengthy observations was attended with con- 
siderable difficulty. In September, however, a small decked fishing 
boat, called the Blioda, was anchored off Fort Augustus in about 300 
feet of water. The anchoring of this boat caused some anxiety, but it 
was ultimately accomplished by means of a large mushroom anchor, 
which, with the necessary length of chain, was put at the disposal of 
Sir John Murray through the courtesy of Mr. Davidson, superintendent 
of the Caledonian canal. 
This boat was primarily intended to accommodate the electrical 
thermometers which were installed, but it came to be very largely used 
for taking observations by means of mercury thermometers. Lengthy 
series of observations could be taken in comfort whatever the state of 
the weather, and with great economy in time. It was possible to 
use three or four sounding machines and thermometers at once, and 
consequently a series of observations could be made much more 
expeditiously than when only one sounding machine was used. 
* The water of Loch JSess was submitted to analysis by Dr. Tetlow, who found 
nothing- abnormal about the water, except its softness and freedom L’om mineral matter, 
the total solids being equal to only 2-9224 parts per 100,000 (1-9012 parts of fixed solids, 
and 1-0212 parts of volatile solids); the principal constituents are sodium and calcium 
chlorides, while magnesium chloride, iron, potassium, silicon, carbonic acid, and sulphuric 
acid are present in traces. 
