62 BATHYMETRICAL SURVEY OF 



been found towards the north-eastern end of this basin, and com- 

 paratively close to the eastern shore. The volume of water contained 

 in the loch is estimated at 76,236,000 cubic feet, and the mean depth 

 at 9J feet. The loch is on the whole comparatively shallow, about 63 

 per cent, of the bottom being covered by less than 10 feet of water, 

 while only 9 per cent, of the bottom is covered by over 20 feet of water. 

 The loch was surveyed on April 16, 1902, over 100 soundings being 

 recorded. The surface of the water was found to be 962 feet above 

 sea-level by the officers of the Ordnance Survey in 1897. The tem- 

 perature of the surface water at 6 p.m. on April 16, 1902, was 45 0- 2. 



Loch Bd (see Plate XVI.). Loch Ba (or A-baw) is extremely 

 irregular in outline, studded with large and small islands, and with 

 many rocks and boulders. Its length from south-west to north-east in 

 a straight line is over 2 miles, and following the axis of deep water 

 about 2J miles. Its maximum breadth in the southern portion from 

 east to west is over a mile, and the mean breadth is nearly half a mile. 

 Its waters cover an area of about 585 acres, or nine-tenths of a square 

 mile, and it drains directly an area of 4J square miles, but, since it 

 receives the outflow from Loch Buidhe, Lochan na Stainge, and 

 Lochan na h-Achlaise, its total drainage area is nearly 17^ square miles, 

 or nineteen times the area of the loch. 



The bottom of Loch Ba is very irregular. The deepest water occurs 

 in the northern portion between the islands of Eileaii Molach and 

 Eilean na h-Iolaire, where there is a small basin less than a quarter of 

 a mile in length, and over 20 feet in depth, the maximum depth of 

 30 feet having been observed about one-sixth of a mile to the north of 

 the northern point of Eilean Molach. An isolated sounding of 20 feet 

 was taken close to the western shore of the southern portion of Eilean 

 Molach. There are three irregular basins with depths exceeding 10 

 feet : the central one, enclosing the 20-feet basin, and extending on both 

 sides of Eilean Molach and to the west and north of Eilean na h-Iolaire, 

 is nearly three-quarters of a mile in length and over a quarter of a mile 

 in breadth ; the southern one, occupying the wide south-eastern portion 

 of the loch, is nearly half a mile in maximum diameter ; and the third, 

 situated in the north-eastern extension of the loch, is nearly half a mile 

 in length and nearly a quarter of a mile in breadth. The volume of 

 water contained in the loch is estimated at 206,497,000 cubic feet, and 

 the mean depth at 8 feet, being 27 per cent, of the maximum depth. 

 The length of the loch is 378 times the maximum depth and 1402 times 

 the mean depth. Over 70 per cent, of the floor of the loch is covered by 

 less than 10 feet of water, and only 1| per cent, by more than 20 feet of 

 water. The loch was surveyed on April 17 and 18, 1902, over 300 

 soundings having been taken. The level of the loch was' determined by 

 the Ordnance Survey officers in 1897 as being 957 feet above sea-level. 



