80 
BATHYMETRICAL SURVEY OF 
43°’5. A series of temperatures was taken below the surface at 1 p.m, 
on April 24, 1902, in 102 feet of water, with the following results; — 
Surface 
5 feet 
10 „ 
20 „ 
50 ,, 
70 „ 
100 „ 
43° *5 Fahr. 
43° o ,, 
43° -4 ,, 
43° *2 „ 
43° 0 ,, 
42° '6 ,, 
42° -4 ,, 
showing a gradual decrease of temperature from surface to bottom, the 
range of temperature being 1°-1 in the 100 feet of water. 
Loch Tay (see Plates XXIV. and XXV.). — Loch Tay is one of the 
largest of the Scottish fresh-water lochs, unsurpassed in the beauty of 
its surroundings, and well known to anglers on account of its salmon 
fishings, which are among the best in Scotland. It is also a good trout- 
fishing loch, having been much improved within recent years by being 
stocked with Loch Leven trout. The scenery around the loch is very 
fine — grand and wild towards the south-west end, with the mighty Ben 
Lawers rising from its northern shores about half-way down the loch, 
becoming more sylvan in character towards the north-east end, a 
splendid view presenting itself to the eyes of a spectator from Kenmore 
Bridge (see Fig. 24). 
Loch Tay is the largest loch in the basin of the river Tay, though 
Loch Ericht is a very formidable rival for this distinction, as will be 
seen from the following comparison : — 
Loch Tay. 
Loch Ericht. 
Length... 
14’55 miles. 
14‘5 miles. 
Maximum breadth ... 
1*07 miles. 
1 ’0 mile. 
Mean breadth... 
' 0-70 mile. 
0‘5 mile. 
Superficial area 
I 10T9 square miles. 
7 '21 square miles. 
Maximum depth 
508 feet. 
512 feet. 
Mean depth ... 
199 076 feet. 
189-201 feet. 
Volume of water 
56,550 million cub. ft. 
38,027 million cub. ft. 
This comparison shows that the maximum depth observed in Loch 
Ericht slightly exceeds that observed in Loch Tay, but in all other 
respects Loch Tay has the advantage, though as regards length and 
maximum breadth the two lochs are almost identical. 
Loch Tay is over 14 J miles in length, and over one mile in maximum 
breadth, the mean breadth being nearly three-quarters of a mile, or 
nearly 5 per cent, of the length. Its waters cover an area of over 6500 
acres, or over 10 square miles, and it drains directly an area of about 
187 J square miles, but since it receives the outflow from Lochs Dochart 
and lubhair, its total drainage-area is over 232 square miles, or nearly 
