580 THE FRESH-WATER LOCHS OF SCOTLAND 
Lake Vener, the third largest lake in Europe, with a length of 
112 miles, a breadth of 56 miles, and an area of 2149 square miles, 
is situated towards the west of the depression, and drains to the 
Kattegat through the Gota ; the Klar, the greatest Scandinavian 
river, flo^vs into the lake. Lake Vener lies at an elevation of 144 feet 
above sea-level ; the maximum depth is 292 feet, the mean depth 108 
feet, and the volume of water contained in the lake is estimated at 
about 6,357,600 million cubic feet. It is connected with Lake Vetter 
by canal. 
Lake Vetter lies at an elevation of 289 feet above sea-level, has 
a length of 80 miles, an average width of about 18 miles, and has 
an area of 733 square miles. The maximum depth is 413 feet, 
the mean depth 128 feet, and it is estimated to contain about 
2,543,000 million cubic feet of water. It receives short streams from 
the plateau of Southern Sweden, and discharges eastwards by the large 
Motala River to the Baltic. By the eastern branch of the Gota 
Canal it has navigable communication with Lake Vener. 
Lake Malar also drains to the Baltic. It lies at an elevation 
of only IJ feet above sea-level, and covers an area of 450 square 
miles. The maximum depth is 210 feet, the mean depth 26 feet, and 
the volume is estimated at about 353,200 million cubic feet. 
Lake Hjelmar lies about 70 feet above sea-level, and covers an 
area of 185 square miles. The greatest depth is 65 feet, and the 
outflow of the lake is to the Baltic. 
Reference may here be made to the remarkable temperature con- 
ditions recorded in a small lake in the island of Tysnos, off the coast 
of Norway, the depth of which does not exceed 15 feet.^ When 
visited in 1888 the temperature at the surface was 54° '7 F. (12°"6 C), 
but at one foot below the surface it rose to 60" F. (15° "56 C), at four 
feet down it was 69°-2 F. (20°-67 C), at seven feet down it was 73°-0 F. 
(22°-78 C), the maximum temperature of 74°-0 F. (23°-33 C.) being 
reached at ten feet below the surface ; further down the temperature 
fell distinctly, being only 72'-0 F. (22°-22 C.) at the bottom. On 
30th June 1888 the maximum temperature was no less than 81°'3 F. 
(27° '4 C.) at about seven feet beneath the surface, and fell to 78° "8 F. 
(26° "0 C.) by July 21, being then between nine and ten feet below the 
surface, and to 73° 9 F. (23' '28 C.) by 11th August at about eleven feet 
beneath the surface. Careful search had been made for a hot spring, 
but nothing of the kind could be found, and the conclusion was that 
these phenomenal temperatures were due to solar radiation ; this is 
supported by the fact that the specific gravity m situ of the inter- 
mediate and hottest layer lies between that of the surface and bottom 
1 See GibsoD, Seventh Annual Report of the Fishery Board for Scotland, Part IIL 
p. 433, 1889. 
