226 BATHYMETRICAL SURVEY OF 



Loch of Harray. It is surrounded by a boggy flat, except on the north, 

 where the Hill of Greenay rises. Rock is seen at several points on the 

 north-east shore. The length is fully half a mile, and the breadth fully 

 a quarter of a mile. The bottom is flat, with a maximum depth of 3 feet, 

 and a large area of this same depth. The north-west corner is filled with 

 reeds. The mean depth is 1J feet, the area about 77 acres, and the volume 

 5 millions of cubic feet. The drainage area measures fully 3 square 

 miles. The outflow is westward by a small stream, utilized as a mill 

 stream, into the Burn of Warth. The surface was 51-7 feet above sea- 

 level on September 6, 1906. 



Loch of Isbister (see Plate XCL). A small loch, square or somewhat 

 cruciform in shape, near the Church of Twatt, and 1J miles south of the 

 Loch of Boardhouse. It is surrounded by extensive boggy flats, especially 

 to the west, so that a rise of even a foot in level would greatly extend 

 the area of the loch. It is extremely shallow, and much obstructed by 

 stones. The length from north to south is nearly two-thirds of a mile ; 

 the breadth from east to west is a little less. The greatest depth, 3 feet, 

 is at the east end. The mean depth is 1J feet, the area about 80 acres, 

 and the volume 5 millions of cubic feet. The drainage area is 4J square 

 miles. A drain with sluice leads to the Loch of Banks. The surface 

 temperature was 64- 6 Fahr. on September 1, 1906, the highest observed 

 in Orkney. The bottom is free from weeds, except in the southern corner, 

 and covered with grey clayey mud. The level was estimated at about 



40 feet above sea-level. 



Loch of Kirbister (see Plate XCII.). The Loch of Kirbister (or Loch 

 of Orphir) is a loch of moderate size, and somewhat triangular shape, 

 in the parish of Orphir, 5 miles south-west of Kirkwall. It lies amid 

 cultivated land in a broad valley between hills of over 700 and 800 feet 

 respectively. It is l miles long, and fully half a mile broad. The 

 bottom is almost perfectly flat, a great central area being uniformly 

 5 feet deep. The maximum depth is 6 feet, and the mean depth 4 feet. 

 The area of the surface is about 227 acres, and the volume of water 



41 millions of cubic feet. The drainage area measures 8 square miles. 

 The largest burns are those entering at the two ends of the loch. The 

 outflow is near the southern end, by a mill burn, about half a mile long, 

 with a rocky channel, flowing into Waulkmill bay. The surface was 

 52-1 feet above sea-level on August 14, 1903. The surface temperature 

 was 57'0 Fahr. 



Loch of Tankerness (see Plate XCII.) is a triangular loch of moderate 

 size, near St. Andrew's church, 4 miles east of Kirkwall, surrounded 

 by pasture and wet meadows. It is nearly a mile long by half a mile 

 broad. It is shallow and flat-bottomed, very gradually deepening from 



