144 
BATHYMETKICAL SURVEY OF 
10-feet basin is continuous, and about a mile in length, approaching com- 
paratively close to the east end. The maximum depth of 23 feet was 
observed immediately to the east of the central constriction, the depth in 
the narrows being 14 feet, and in the large western expansion the greatest 
depth is 19 feet. The volume of water is estimated at 69 million cubic 
feet, and the mean depth at 10 feet. The area draining into the loch is 
about square miles. The survey was made on June 29, 1903, when the 
elevation was 194'G feet above the sea ; the Ordnance Survey map gives 
I96 0 feet, but the date when levelled is not indicated. A drift-mark was 
observed 3 feet above the water, which might fall perhaps a foot lower, 
giving a range in level of about 4 feet. The water was very dirty and 
green in colour, and nearly uniform in temperature, the readings at the 
surface and at 10 feet being 61°*9 Fahr., at 15 feet 61°’8, and at 20 feet 
61°*5. 
Balgavies Loch (see Plate LI.) is situated less than half a mile to the 
east of Eescobie Loch, and about 5 miles from Forfar. The length is half 
a mile, and the width nearly uniform, 250 to 300 yards, the superficial 
area being about 52 acres, of which about 60 per cent, is covered by less 
than 10 feet of water. The deepest part lies near the east end, where the 
maximum depth of 32 feet was recorded, but there is an isolated basin in 
the south-western portion of the loch with a greatest depth of 18 feet. 
The volume of water is estimated at 22 million cubic feet, and the mean 
depth at 9f feet. Balgavies Loch drains directly an area of two-thirds of 
a square mile, but since it receives the overflow from Rescobie Loch, the 
total drainage area is about 6 square miles. The loch was surveyed on 
June 29, 1903, when the elevation was 194*5 feet above the sea; the 
Ordnance Survey map gives 195*1 feet, but the date when levelled is not 
indicated. A drift-mark was observed 2 feet above the water, which 
might fall a foot lower. Serial temperatures were taken in the deepest 
part of the loch, with the following results : — 
Surface 62°-5 Fahr. 
10 feet 62°-4 „ 
There was a range of 10° throughout the body of water, the upper 10 
feet being practically uniform, while between 10 and 20 feet there was a 
fall of 6°*6, and between 20 and 30 feet a further fall of 3°*3. 
20 „ 
30 „ 
55°-8 
52°-5 
