358 BATHYMETRICAL SURVEY OF 



found to be 94-24 feet, as compared with 93*2 feet observed by the 

 officers of the Ordnance Survey on July 1, 1870. Loch Lochy contains 

 37,726 millions of cubic feet of water, or nearly 50 per cent, more than 

 Loch Arkaig, the second largest loch in the basin. 



At the north end a small basin, called Ceann Loch, measuring one- 

 half by one-third of a mile, and having a maximum depth of 66 feet, is 

 cut off from the main loch by a narrow channel** in which the greatest 

 depth is 40 feet. 



The main loch is a simple basin, with the U-shaped section charac- 

 teristic of glacier-formed lakes. All the contours are continuous, those 

 at 50 and 100 feet enclosing areas little less than the total length of the 

 loch. The area enclosed by the 200-feet contour measures 6| miles in 

 length, by the 300-feet contour 4J miles, and by the 400-feet contour a 

 little over 3 miles in length. The 500-feet contour encloses a very 

 small area, one-third of a mile long by one-eighth of a mile broad, 

 just about the middle of the loch, and includes the deepest sounding in 

 531 feet. From opposite the mouth of the river Arkaig to the outflow, 

 the loch shallows rapidly and the contours are irregular. 



The following table gives the approximate areas between the 

 consecutive contour-lines drawn in at intervals of 100-feet, with the 

 percentages to the total area of the loch : 



to 100 feet 923 acres 24 -4 per cent. 



100 200 ,, 937 24-8 



200,, 300 651 ,, 17-2 



300,, 400 ,, 571 15-1 



400,, 500 678 17'9 

 Over 500 , 23 . 0'6 



3783 , 100-0 



The flat-bottomed character of the basin is indicated by the 

 comparatively large area covered by water between 400 and 500 feet 

 in depth, an area greater than in the two shallower zones; the zone 

 between 100 and 200 feet, also, is rather larger than the shore zone. 



Temperature Observations * The surface temperature varied from 

 43-5 Fahr. to 42-l. A series taken on April 29 showed the small 

 range from the surface to 425 feet of only l-2. It will be seen from 



* During the past twenty years Sir John Murray has taken many temperature obser- 

 vations in Loch Lochy, and has published and discussed the results in the following papers, 

 to which the reader is referred for further details : (1) " On the Effects of Winds on the 

 Distribution of Temperature in the Sea- and Fresh- water Lochs of the West of Scotland," 

 Scott. Geogr. Mag., vol. 4, p. 345, 1888; (2) " On the Temperature of the Salt- and Fresh- 

 water Lochs of the West of Scotland, at Different Depths and Seasons, during the years 

 1887 and 1888," /Voc. Roy. Soc. Edin., vol. 18, p. 139, 1891; (3) "Some Observations on 

 the Temperature of the Water of thu Scottish Fresh-water Lochs," Scott. Geogr. Mag., 

 vol. 13, p. 1, 1897. 



