THE FRESH- WATER LOCHS OF SCOTLAND. 185 



majority of the lochs. This loch will therefore be described with some 

 fulness, and those which essentially resemble it, differing mainly in size, 

 will be included in the summary table giving the principal dimensions. A 

 few of the other large lochs, and any of rather different structure or 

 coming nearer true rock-basins, as well as Loch Obisary, on account of its 

 size and depth, will be described with more detail. 



Of the thirty-nine lochs which were surveyed thirty-two are fresh- 

 water, and the remaining seven are more or less salt. Some of those 

 regarded as fresh may receive very exceptional tides. Lochs Duin, Strumore, 

 Oban a' Chlachain, and Leodsay are purely tidal, receiving ordinary tides, 

 though their level is only moderately affected by the tides. Loch Strnmore 

 rises and falls about 2 feet, while the whole tide is about 18 feet. Loch 

 Oban nam Fiadh is of an intermediate character, the flora and fauna 

 towards the lower end being purely marine, while in the upper part the 

 fauna is fresh-water. Loch Caravat is so fresh that we only learned its 

 tidal character from the account of the natives. 



There are no important streams in North Uist. In the western part of 

 the island are some a few miles in length, and large enough to be dignified 

 by names, but in the part surveyed, where most of the lochs are situated, 

 they are extremely short, generally only a few yards long. The stream 

 which drains Loch Scadavay and its connected chain of lochs, though of 

 fair size, is of inconsiderable length. This stream, with those connecting 

 all the larger tributary lochs, has a total length of only about a mile, and 

 the longest portion of it, from Loch Scadavay to Loch Garbh-Abhuinn Ard, 

 is less than half a mile long. 



The thirty-nine lochs surveyed belong to nineteen distinct basins. Most 

 of these contain only one loch, which usually drains directly to the sea by 

 a short channel, often no longer than the width of the public road. There 

 are twelve of these lochs, which are the only lochs in the basins to which 

 they belong, or the only lochs surveyed. They are Lochs Veiragvat, an 

 Duin, nan Geireann, Hosta, Oban a' Chlachain, Leodsay, an Tomain, Obisary, 

 a' Chladaich, Tormasad, a' Bharpa, and Buaille. The only important lochs 

 among these are Lochs Obisary and nan Geireann. 



There are only six of the basins in which more than one loch was 

 surveyed. These basins cannot be distinguished by the names of the 

 streams draining them, as these are usually nameless. They are here 

 distinguished by the name of the most important loch in the basin, or by 

 that of the lowest, into which the others drain. 



The Scadaiay Basin. This is by far the largest of the basins, and 

 includes ten lochs which were sounded, besides many smaller ones. The 

 combined surface areas of all the lochs have a total measurement of nearly 

 :3f square miles, Loch Scadavay itself contributing nearly half of this. The 

 combined drainage area extends to 14J square miles, and of this Loch 

 Scadavay alone, excluding its tributary lochs, drains more than half, or over 



