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 The observations were originally made from 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 Rlioda, 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 Ness was submitted to analysis by Dr. Tetlow, who found 

 nothing abnormal about the water, except its softness and freedom from 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. 



