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 IJ 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 
