100 
BATHYMETRICAL SURVEY OF 
feet from tlie eastern shore. The last sounding indicates a very steep 
slope in this position, equal to 1 in 1*9, and off the western shore further 
north a similar steep gradient is indicated by a sounding of 36 feet 
taken about 100 feet from the shore, equal to 1 in 2*8. The soundings 
reveal, further, an ill-defined shallow ridge, running in a north and 
south direction across the wide portion of the loch, covered by less than 
30 feet of water, with deeper water on both sides. The area of the lake- 
floor covered by less than 25 feet of water is about 23 acres, or 64 per 
cent, of the entire area of the loch. Loch nan Eun was surveyed on 
July 2, 1903 ; its elevation above the sea could not be determined from 
bench-mark, but, estimated from spot-levels, its elevation must be about 
2575 feet. There is evidently very little variation in the level of the 
surface of the water, since no drift-mark indicating a higher level could 
be seen, and a fall of a few inches would cease to feed the outflowing 
burn, which forms a waterfall a few yards from the loch, the top of the 
fall being at nearly the same level as the loch. 
T emperature Observations . — The temperature of the surface water on 
commencing the survey at 10.30 a.m. was 50°*0, and a series of tem- 
peratures taken at noon in the deepest part of the loch gave the 
following results : — • 
Surface ... ... ... ... ... ... ... 50°’8 Fahr. 
25 feet 50° ‘5 ,, 
45 „ 49°-8 „ 
Lochs Craiglush, Lowes, Butterstone, Clunie, Drumellie, Bae, 
Fingask, White, Black, and the Stormont lochs form a connected series 
of lochs all draining into the Lunan burn, which flows into the river 
Isla shortly before its junction with the river Tay; they all contain 
pike and perch, and trout also are taken in Lochs Craiglush, Lowes, and 
Drumellie. The group nearest the source of the Lunan burn consists 
of Lochs Craiglush, Lowes, and Butterstone. 
Loch of Craiglush (see Plate XXIX.). — The Loch of Craiglush is 
situated in Drumbuie wood near Dunkeld, and is almost surrounded by 
trees. Its shores are weedy, and where the Lunan burn enters there is 
a large grassy flat formed of material brought down by the stream. It 
trends in a north-east and south-west direction, and is over half a mile 
in length, with a maximum breadth of over a quarter of a mile, the 
mean breadth being nearly one-flfth of a mile, or 32 per cent, of the 
length. Its waters cover an area of about 70 acres, or over one-tenth 
of a square mile, and it drains an area of about 5| square miles — an 
area 52 times greater than the area of the loch. Over 50 soundings were 
taken, the maximum depth observed being 44 feet. The volume of 
water contained in the loch is estimated at 49,079,000 cubic feet, and 
the mean depth at 16 feet, or 37 per cent, of the maximum depth. The 
