76 BATHYMETRICAL SURVEY OF 



the soundings taken by different surveyors. Mr. Grant- Wilson took 

 over 180 soundings in 1888, Sir John Murray and the late Mr. F. P. 

 Pullar took about 150 soundings in 1900, and the Lake Survey took 500 

 soundings in 1902, but in no case was the depth found to exceed 288 

 feet. On the accompanying map only the Lake Survey soundings are 

 laid down, and the contour-lines drawn in from them. 



Loch Earn is 6J miles in length, and four-fifths of a mile in maximum 

 breadth, the mean breadth being three-fifths of a mile, or 9J per cent, 

 of the length. The waters of the loch cover an area of over 2400 

 acres, or nearly 4 square miles, and it drains an area of over 54J 



FIG. 22. LOCH EARN. 



(Photograph by J. Parsons, B.Sc.) 



square miles an area fourteen times greater than the area of the 

 loch. Five hundred soundings were taken in Loch Earn, the maximum 

 depth observed being 287 feet, which agrees very well with the 

 maximum recorded by Mr. Grant-Wilson in 1888, viz. 48 fathoms, 

 or 288 feet. The volume of water contained in the loch is estimated 

 at 14,420,638,000 cubic feet, and the mean depth at 138 feet, or 48 

 per cent, of the maximum depth. The length of the loch is 118 times 

 the maximum depth, and 245 times the mean depth. 



Loch Earn forms a simple basin, the lake-floor sinking gradually on 

 all sides down to the greatest depth, as is well shown by the longitudinal 

 and three cross-sections on the map. The 50-feet contour-line follows 



