242 
BATHYMETRICAL SURVEY OF 
mile ; there are no feeders of any importance, and the Twatt burn conveys 
the overflow into Bixter Voe. 
On July 17, 1903, the surface was 77*9 feet above sea-level; on 
October 24, 1877, the Ordnance Survey officers found it to be 78*7 feet. 
The surface temperature was 54°*8 Fahr. « 
Loch of Collaster (see Plate C.) is a very small triangular loch, lying 
1 mile north-west of Aithsting church. It measures fully one-third of a 
mile from north to south, by one-fifth of a mile broad at the north end. 
It is very shallow, the maximum depth of 10 feet being near the north end. 
It receives on the west the Burn of Shunalittle from Loch Shunalittle. 
The Twatt burn carries the overflow to Kirkhouse Water (not surveyed), 
whence the Burn of Quinigill issues, and, joining the Twatt burn from 
the Loch of North-house, enters Bixter Voe. The superficial area is 
about 25 acres, the mean depth nearly 6 feet, and the volume of water 
7 millions of cubic feet ; three soundings in the maximum depth of 
10 feet were taken near the northern end. It drains an area of less 
than half a square mile. The height of the loch above sea-level could 
not be ascertained. 
On July 14, 1903, the surface temperatures was 53°'0 Fahr. 
Loch of Strom (see Plate Oil.) lies 5 miles due north of Scalloway, and 
is one of the longest lochs in Shetland, but is very narrow. It is a tidal 
loch. Its axis runs nearly due north and south. The valley in which 
it lies is here very narrow, and the hills which bound it slope steeply 
into the loch. On the east the hills are higher and covered with 
heather, and rock shows at many points on the lake-shore; on the 
west the lower hills are rugged and covered with grass ; rock shows 
at the promontory called Quoy ness, on the west shore, and at the 
extreme south end. South of the Strom bridge the west shore is a terrace 
of gravel with boulders. There is rock at the north end of Strom 
bridge, and at the sea end of the Strom on the south side. The tide 
appears to have little effect on the level of the loch, which was 
0-5 foot above sea-level on the date of the survey (August 1, 1903), but it 
must renew the water with sufficient frequency to permit of the growth of 
fucoids and other marine organisms over the whole of the bottom, even to 
the extreme north. The northern part of the loch, rather more than half 
the length, is very narrow; south of Quoy ness is a broader portion. 
The length is a little over miles, which slightly exceeds that of the 
Loch of Cliff, unless the narrow eastern arm is included in the length of 
that loch. The greatest breadth, one-third of a mile, is just south of 
Quoy ness. 
The Loch of Strom is very shallow. East of Quoy ness, on each side 
of the narrow island, the depth is only 6 feet, and there is deeper water 
both to the north and south. In the northern basin, the central part of 
