LOCHS OF THE FORTH BASIN. 
Within this basin the following lochs were sounded by Sir John Murray 
and the late Mr. Fred. P. Pullar, viz., Lochs Katrine, Arklet, Achray, 
Vennachar, Drunkie, Voil, Doine, Lubnaig, Chon, Dubh, Ard, 
Menteith, and Leven. The eight first-mentioned lochs belong to the 
catchment-basin of the river Teith, and have a special interest from 
being directly or indirectly connected with the excellent water-supply 
to the city of Glasgow.* Loch Arklet belongs to the catchment-basin 
of Loch Lomond, but the Corporation of Glasgow has power to divert 
its waters into the catchment-basin of Loch Katrine. 
Loch Katrine (see Plate IV.). — Loch Katrine is one of the best 
known and most beautiful of the Scottish lochs. The celebrated 
* In the year 1855 the Corporation of Glasgow was empowered by Act of Parliament 
to raise Loch Katrine 4 feet above, and to draw it down 3 feet below, the previous 
summer level, thus giving a total available depth of 7 feet for the supply of water to 
the city, the quantity of water to be drawn from the loch being restricted to fifty 
million gallons in twenty-four hours. For the purpose of providing compensation water 
to the riparian owners on the river Teith, power was also given to raise Loch Vennachar 
5 feet 9 inches above its previous summer level, and to draw it down 6 feet, and 
also to raise Loch Drunkie 25 feet. An aqueduct was built from the southern shore of 
Loch Katrine to Glasgow, 8 feet wide and 8 feet high throughout, with a semicircular 
top, and having a fall towards Glasgow of 10 inches per mile. At first only a portion 
of the available fifty million gallons per day was conveyed to Glasgow, but by the 
end of 1881, the whole of the works necessary to complete the oidginal design wei’e 
finished. In the year 1884 it was found necessary to provide a larger quantity of water 
in order to keep pace with the growth of the city, and it was then found that the rough- 
ness of the rock sides of the aqueduct had a very retarding influence upon the velocity 
of the water, and that the aqueduct could not be made to discharge more than forty-two 
million gallons per day. Power was subsequently obtained from Parliament to build a 
second aqueduct, to raise Loch Katrine an additional 5 feet, and to convert Loch Arklet, 
which flows into Imch 1 omond, into a reservoir by raising it 25 feet in level. These 
works are now in progress, and when completed are estimated to give a supply of 
seventy-five millions of gallons of Avater per day to the city of Glasgow. Should a still 
greater supply be necessary in the future, it is believed this can be obtained by connecting 
Loch Doine Avith Loch Katrine by a tunnel through the intervening hills, and by con- 
structing an embankment at the bottom of Loch Doine to raise the water-level 30 feet, 
and another at the bottom of Loch Voil to raise the Avater-level of that loch 10 feet, 
and if still more water were wanted, IjOcIi Lubnaig ct)uld furnish it (see papers by James 
M. Gale, Esq., m. inst. C.e., in the Trans. Inst. Engineers in Scotland., vols. vii., xii. , 
xxvi., and xxxviii., and his Eeport on the proposed extension of the GlasgoAv Corporation 
Water Works, dated May 17, 1884). 
L 
