THE FRESH-WATER LOCHS OF SCOTLAND. 
85 
Strathtay, lying to the north-east of Loch Kennard and west of Loch 
Skiach, and flowing by the Balnaguard burn into the river Tay shortly 
before its junction with the river Tummel, is over a quarter of a mile in 
length, with a maximum breadth of about one-eighth of a mile, the 
mean breadth being about one-sixteenth of a mile or 21 per cent, of the 
length. Its waters cover an area of about 11^ acres, and it drains an 
area 13 times greater, or about a quarter of a square mile. Twenty- 
five soundings were taken, the maximum depth observed being 12 feet. 
The volume of water is estimated at 2,888,000 cubic feet, and the mean 
depth at nearly 5^ feet, or 48 per cent, of the maximum depth. The 
length of the loch is 123 times the maximum depth, and 258 times 
the mean depth. The loch forms a simple basin; the deeper water is 
found towards the southern end, the three soundings exceeding 10 feet 
being centrally placed in the southern half of the loch. Only three 
soundings were taken under 5 feet close to the shore, so that the slope 
of the bottom is on the whole moderately steep. The area of the lake- 
floor covered by less than 10 feet of water is over 10 acres, or 88 
per cent, of the total area of the loch, and only a small proportion of this 
area is covered by less than 5 feet of water. Loch Scoly was surveyed 
on May 29, 1903. The temperature of the surface water was 63°*0 
Fahr., and a reading at 5 feet gave the same result, while a reading at 
10 feet gave 56°*0 — a fall of 7°'0 in the temperature of the water at 
10 feet as compared with that at 5 feet. 
Loch Or die (see Plate XXVI.). — Loch Or die is a very pretty loch 
situated amid grouse-moors to the east of the river Tay, and surrounded 
by wooded hills; it is a good trouting loch, but strictly preserved. It 
trends in an east-and-west direction, being widest towards the west end 
and narrowing somewhat towards the east end. It is nearly two-thirds 
of a mile in length, and nearly half a mile in maximum breadth, the 
mean breadth being over a quarter of a mile, or 44 per cent, of the 
length. Its waters cover an area of about 116 acres, or nearly one-fifth 
of a square mile, and it drains an area nearly 24 times greater — over 
4^ square miles. Sixty-five soundings were taken, the maximum depth 
observed being 69 feet. The volume of water is estimated at 133,110,000 
cubic feet, and the mean depth at 26J feet, or 38 per cent, of the 
maximum depth. The length of the loch is 49 times the maximum 
depth, and 128 times the mean depth. Loch Ordie is extremely simple 
in conformation, the bottom sinking gradually on all sides down to the 
greatest depth, which is approximately centrally placed, though rather 
nearer the west than the east end. The 25-feet basin is about two-fifths 
of a mile in length and over a quarter of a mile in maximum width, 
while the 50-feet basin is about a quarter of a mile in length and one- 
seventh of a mile in maximum width. The area of the lake-floor 
covered by less than 25 feet of water is about 66 acres, or 57 per cent. 
