120 
BATHYMETRICAL SURVEY OF 
with trees and grass, and is said by Mr. Patrick Murray to be natural; 
the small island to the south is artificial, composed of stones, with a 
submerged causeway running eastward to the shore; the island in the 
south-western portion of the loch is also artificial, built on piles, and 
is said to have been used as a prison. Loch Monzievaird trends in a 
north-east and south-west direction, being widest and deepest towards 
the south-western end ; there is a central constriction which divides the 
loch into two basins. It is over half a mile in length, with a maximum 
breadth of one-fifth of a mile, the mean breadth being over one-tenth 
of a mile, or 19 per cent, of the length. Its waters cover an area of 
about 37 acres, and it drains an area of 1§ square miles — an area 27 
times greater than the area of the loch. Over 60 soundings were taken, 
c the maximum depth observed being 39 feet. The volume of water con- 
tained in the loch is estimated at 23,905,000 cubic feet, and the mean 
depth at nearly 15 feet, or 38 per cent, of the maximum depth. The 
length of the loch is 74 times the maximum depth, and 198 times the 
mean depth. The depth of water in the central constriction is 7 feet, 
with deeper water on both sides, the maximum depth observed in the 
north-eastern portion of the loch being 20 feet, while the maximum 
depth of the loch (39 feet) occurs in the south-western portion, com- 
paratively near the western shore, where the Conalter burn flows in 
and the Downie burn flows out. The area of the lake-floor covered by 
less than 10 feet of water is about 15 acres, or 39 per cent, of the total 
area of the loch; that covered by water between 10 and 20 feet in 
depth is about 14 acres, or 37 per cent. ; that covered by water between 
20 and 30 feet in depth is about 4 acres, or 12 per cent. ; and that 
covered by more than 30 feet of water is about 4 acres, or 12 per cent, 
of the entire area of the loch. Loch Monzievaird was surveyed on June 
8, 1903 ; its elevation above the sea was not determined by levelling, 
but it is evidently slightly under 200 feet since the 200-feet contour 
almost coincides with the shore-line. The outflow is controlled by a 
sluice, and on the date of the survey the water in the loch was very 
low. 
- T emijerature Observations. — Temperature observations taken in the 
deepest part of the loch gave the following results : — 
Surface 68°'0 Fahr. 
5 feet 68° -0 ,, 
10 ,, .. 60°-5 ,, 
15 ,, 53°-0 „ 
20 ,, 51°*0 ,, 
36 „ 47°-4 „ 
This series shows a range of temperature from surface to bottom 
amounting to 20°*6, there being a fall of 7°’5 between 5 and 10 feet, 
and a similar fall between 10 and 15 feet — a decrease of 15° in the 10 
feet of water, equal to l°-5 per foot. 
