30 
BATHYMETRICAL SURVEY OF 
LOCHS OF THE SCOURIE BASIN. 
The two principal lochs within this basin (Lochs an Laig Aird and 
a’ Bhaid Daraich) were sounded by the Lake Survey, and were found 
to form a complete contrast both in outline and conformation. Loch 
an Laig Aird is most irregular in these respects, while Loch a’ Bhaid 
Daraich is quite simple. The overflow from Loch an Laig Aird is carried 
by the Allt Loch an Laig Aird into Loch a’ Bhaid Daraich, which flows by 
the short stream Allt a’ Mhuilinn into Scourie bay on the west coast 
of Sutherland. 
Loch an Laig Aird (see Plate XI.).— Loch an Laig Aird is situated 
about a mile to the north-east of Scourie, and half a mile to the south 
of Loch nam Breac. The waters of the loch almost entirely encircle 
a large promontory of land, the connecting isthmus being only about 
100 feet across, and cover an area of about 67 acres. The loch is on 
the whole shallow, the area of the bottom covered by less than 20 feet 
of water being about 51 acres, or 76 iper cent, of the total area. The 
deepest part of the loch is in the arm stretching south-westwards from the 
large promontory, where there is a long narrow basin exceeding 40 feet in 
depth, the deepest sounding in 42 feet having been taken close to the 
southern shore, about a quarter of a mile from the south-western extremity 
of the loch, and only about 40 feet from shore, so that the slope of the 
bottom at this place is very steep. A steep slope also occurs near the 
south-western extremity of the loch, where soundings in 13 and 14 feet 
were taken about 10 feet from shore. In the broad arm to the east of the 
large promontory the maximum depth observed was 31 feet, and a similar 
depth was found to the north-west of the large promontory. The loch 
was surveyed on September 9, 1902, but the elevation of the lake-surface 
above the sea could not be determined. 
Temperature Observations . — A series of temj)eratures taken at 5 p.m. on 
the date of the survey, in the deepest part of the loch, gave the following 
results : — 
Surface 57°‘2 Fahr. 
20 feet ... ... ... ... 56°-2 „ 
35 „ 56°-l „ 
Loch a’ Bhaid Daraich (see Plate XL). — Loch a’ Bhaid Daraich is 
situated near the village of Scourie, and little more than a quarter of a 
