THE FRESH- WATER LOCHS OF SCOTLAND. 
225 
Loch of Harr ay (see Plate XC.). — The Loch of Harray, the largest in 
the islands, lies immediately to the north of the Loch of Stenness. The axis 
runs nearly north and south. The southern portion is elongate, with undu- 
lating shore-line ; the northern part bifurcates into two broad inlets, giving 
the whole loch the approximate form of the letter Y. The surrounding 
land is undulating and everywhere low. The east side is principally farm- 
land — there are extensive wet meadows (as at Kirk Ness) — moorland, 
and here and there low cliffs of gravel or rock. The Bridge of Brogar is 
built on the rocky barrier separating the Loch of Harray from the Loch of 
Stenness. The length, measured in a straight line, is 4| miles, and the 
greatest breadth 1| miles. The mean breadth is three-quarters of a mile. 
There are many islands, extensive shoals, and isolated stones. The bottom 
is flat, and the mean depth is about 9 feet. The greatest depth, 14 feet, 
occurs nearly in the narrowest part of the loch. The superficial area is 3| 
square miles, and the volume of water 951 millions of cubic feet. 
The area of country draining into the loch is about 45 square miles. 
The largest streams are the Burn of Hourston, draining several small 
lochs, and entering the Loch of Harray at the north end, and the Burn of 
Netherbrough, flowing in at the east side. The outflow at the Bridge of 
Brogar is, in certain states of the tide, converted into an inflow. There 
was always a current out or in during the survey, but there was never a 
measurable difference of level. The surface was 3*6 feet above sea-level 
on August 21, 1903. The temperature was 55°*0 Fahr. both at the surface 
and at a depth of 14 feet. 
Though there is a free ingress of water from the Loch of Stenness, and 
the shores of that loch are overgrown by marine alg8B close up to the 
Bridge of Brogar, the brackish water entering the Loch of Harray appears 
to be insufficient to have much effect on its biology. No sea-weeds were 
seen on the east side of the Bridge, the water was fresh to the taste, and 
the ordinary fresh-water plankton animals were present. 
Loch of Bosquoy (see Plate XC.). — A small loch of rhomboid form 
near the north-east corner of the Loch of Harray, into which it drains 
by a short mill stream controlled by a sluice. It is surrounded by boggy 
meadowland. There are many islets of reeds in the western part of the 
loch. The length is two-thirds of a mile, and the breadth nearly one- 
third of a mile. The greatest depth is 5 feet near the north shore and 
east end. There is a considerable flat-bottomed area 4 feet deep. The 
mean depth is feet, the area about 65 acres, and the volume 7 millions 
of cubic feet. There is a considerable drainage area (31 miles) chiefly on 
the Hill of Milldoe (734 feet) on the east, from which the Oorrigal burn 
flows. Where it enters the loch the stream is known as the Burn of 
Layaw. The level was estimated at 36 feet above sea-level. 
Loch of Sabiston (see Plate XCI.). — This small loch in the Harray 
basin, also known as the Loch of Housby, lies Ij^ miles north of the 
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