90 BATHYMETRICAL SURVEY OF 



is about 48 acres, or 56 per cent. Loch Broom was surveyed on June 

 11, 1903, but the elevation above the sea could not be determined. 

 Drift-marks were observed 3 feet above the level of the water on the 

 date surveyed. 



The temperature of the surface water on commencing the survey at 

 noon on June 11, 1903, was 60'0 Fahr., and two readings in open 

 water one at the surface and one at a depth of 8 feet gave in each 

 case 60-8. 



Loch Essan (see Plate XXVII.). Loch Essan (or Easain), a hill loch 

 lying to the north of Loch Dochart, containing dark-coloured trout of 

 rare quality, but strictly preserved, flows by the Allt Essan into the 

 river Dochart after it leaves Loch lubhair. It is nearly half a mile in 

 length, and over one-fifth of a mile in maximum breadth, the mean 

 breadth being about one-ninth of a mile. Its waters cover an area of 

 about 32 acres, and it drains an area of over 1J square miles an area 

 32 times greater than the area of the loch. Over 40 soundings were 

 taken in Loch Essan, the maximum depth observed being 18 feet. The 

 volume of water is estimated at 9,664,000 cubic feet, and the mean 

 depth at nearly 7 feet, or 38 per cent, of the maximum depth. The 

 length of the loch is 135 times the maximum depth, and 356 times the 

 mean depth. The loch trends in an east and west direction, and is very 

 irregular in outline. The bottom is also irregular, forming three small 

 basins with depths exceeding 10 feet, the westernmost being the deepest, 

 the maximum depth of 18 feet having been observed about one-sixth of a 

 mile from the west end of the loch. To the east of this western deep 

 basin, and near the centre of the loch, lies a heap of stones around 

 which soundings of 6 feet were taken. A little farther to the east lies 

 the central 10-feet basin, based on a sounding of 11 feet. To the east 

 of the central basin there is a constriction in the outline of the loch in 

 which soundings of 7 and 8 feet were taken, and on approaching the east 

 end the loch widens out, and the bottom sinks to form the third (eastern) 

 10-feet basin, the maximum depth in which is 16 feet. To the south of 

 this eastern basin is a small island, the passage between the island and 

 the shore being obstructed by weeds, and weeds are also abundant along 

 the northern shore. The area of the lake-floor covered by less than 10 

 feet of water is about 26 acres, or 81 per cent, of the total area of the 

 loch, while that covered by more than 10 feet of water is about 6 acres, 

 or 19 per cent. Loch Essan was surveyed on June 16, 1903, the 

 elevation of the surface of the water being estimated at about 1440 feet 

 above sea-level. 



Lochan Breaclaich (see Plate XXVII.). Lochan Breaclaich (or 

 Loch-an-Breacklaich), a hill loch containing fine trout, flows into Loch 

 Tay near its south-west end by the Allt na Breaclaich. It is peculiar 





