THE FRESH-WATER LOCHS OF SCOTLAND. 
73 
twenty-nine times greater than that of the loch. Over 100 soundings 
were taken in Loch Lyon, the maximum depth observed being 100 feet. 
The volume of water contained in the loch is estimated at about 
460,750,000 cubic feet, and the mean depth at 45 feet, or 45 per cent, 
of the maximum depth. The length of the loch is 92 times the maximum 
depth, and 205 times the mean depth. As stated, the loch forms a 
simple basin, the bottom sinking gradually on all sides towards the 
deepest part, which is approximately centrally placed. The deep water. 
FIG. 21. LOCH LYON. 
(P?wtograph by Sir John Murray.) 
however, approaches much closer to the south-west end than to the 
north-east end, where the 25-feet line is distant about a quarter of a 
mile from the shore, probably through silting up of the lake-floor at that 
end. The 25-feet basin is nearly IJ miles in length, the 50-feet basin 
is about IJ miles in length, and the 75-feet basin is about 1^ miles in 
length. The area of the lake-floor covered by less than 25 feet of water 
is about 92 acres, or 39 per cent, of the total area of the loch; the area 
between the 25- and 50-feet contour-lines is about 36 acres, or over 
15 per cent. ; the area between the 50- and 75-feet contours is about 
