THE FRESH-WATER LOCHS OF SCOTLAND. 
157 
largest volume of water of the Spey lochs, it is inferior in superficial area 
to Loch Morlich. Of irregular outline, it exceeds a mile in length from 
south-west to north-east, — from inflow to outflow,— and from east to west 
the diameter is little less than a mile, the mean breadth being nearly half 
a mile. The superficial area is about 280 acres, or less than half a square 
mile, and the total drainage area exceeds 316 square miles, including the 
other lochs lying above it. The maximum depth of 100 feet was observed 
towards the south-eastern shore. The volume of water is estimated at 451 
million cubic feet, and the mean depth at over 37 feet. When the loch 
was surveyed on October 9, 1903, the elevation could not be determined, 
but was estimated to be about 4 feet higher than shown on the Ordnance 
Survey map, where the elevation is given as 721*4 feet above the sea, 
though the date when levelled is not indicated, the water being rather high, 
and flooding the shore in some places. Weeds were abundant at the inlet 
and outflow of the river. The floor of the loch is somewhat irregular, as 
shown by the sinuosity of the contour-lines, apparently brought about by 
the deposition of material by the inflowing river, the contour-lines being- 
pushed out into the centre of the loch. The deep water lies in the 
eastern portion of the loch, sending out a tongue along the western shore 
into the south-western portion of the loch. Nearly one-half of the lake- 
floor is covered by less than 25 feet of water. The temperature of the 
water was practically uniform from surface to bottom, the readings at the 
surface and at 50 feet being identical, viz. 45°*3 Fahr., while a reading at 
85 feet gave 45°*1. 
Loch Alvie (see Plate LTX.) is situated about 2 miles south-west of 
Aviemore, and about 8 miles north-east from Kingussie. It is irregular in 
outline, consisting of a wide central portion, sending out an arm to the 
west and another arm to the north-east. The loch is nearly a mile in 
length, with a maximum breadth of almost half a mile, covering an area of 
about 139 acres, and draining an area of 11 square miles. The deepest 
part lies in the north-eastern portion of the loch, the maximum depth of 
70 feet having been observed less than one-third of a mile from the north- 
east end. An isolated deep basin was also found in the western part of 
the loch, soundings in 50 and 52 feet being recorded less than one-third 
of a mile from the west end, while the wide central portion is less than 50 
feet in depth. One-half of the lake-floor is covered by less than 25 feet of 
water. The volume of water is estimated at 163 million cubic feet, and 
the mean depth at 27 feet. The loch was surveyed on October 9, 1903, 
but the elevation could not be determined ; from spot-levels the elevation 
is apparently about 685 feet above the sea. The surface temperature was 
47°-0 Fahr. 
Loch Gamlina (see Plate LX.), the smallest of the Spey lochs surveyed, 
lies about 2 miles to the south-east of Loch Alvie, on the opposite bank of 
