THE FRESH- WATER LOCHS OF SCOTLAND. 81 



23 times the area of the loch. Nearly 1000 soundings were taken 

 in Loch Tay, and the maximum depth observed was 508 feet. The 

 maximum depth recorded by Mr. Grant-Wilson in 1888, when he took 

 415 soundings in Loch Tay, was 85 fathoms, or 510 feet. The volume 

 of water contained in the loch is estimated at 56,549,745,000 cubic feet, 

 or over one-third of a cubic mile, and the mean cTepth at 199 feet, or 39 

 per cent, of the maximum depth. The length of the loch is 151 times 

 the maximum depth, and 386 times the mean depth. 



Loch. Tay trends in a north-east and south-west direction, being 

 slightly sinuous in outline, somewhat like the italic letter/, as was noted 



FIG. 24. LOCH TAY. FKOM KKNMOUK BRIDGE. 



(Photograph by T. N. Johnton, M.B.. C.M., F.R.S.E.) 



in the case of Loch lubhair, which flows into it. It is extremely simple 

 in conformation, the bottom sloping gradually, without any pronounced 

 irregularities, on all sides down to the deepest part, as is well shown 

 on the longitudinal and cross sections on the map. The 50-feet basin 

 approaches to within less than 400 feet from the south-west end and less 

 than 800 feet from the north-east end, and is 14J miles in length. The 

 slope of the bottom is thus steeper at the south-west end than at the 

 north-east end. In the former position a sounding of 65 feet was taken 

 about 750 feet from shore, giving a gradient of 1 in 11J, and in the 

 latter position a sounding of 80 feet was taken about 1075 feet from 

 shore, giving a gradient of 1 in 13J. The 100-feet basin extends from 



G 



