220 
BATHYMETRICAL SURVEY OF 
Loch Meallan an Fhudair to Loch Maree, and has tapped Lochan Fada, 
slightly lowering its level, thus beheading Abhuinn Gleann na Muic. 
The height of the loch above sea-level was not determined by the 
Ordnance Survey, nor by the Lake Survey when sounded on July 25 
to 28, 1902, owing to absence of bench-marks, but, judging from the 
spot-levels and the 1000-feet contour-line, its level must be about 1005 
or 1006 feet above the sea. 
The length of Lochan Fada is 3| miles, and its maximum breadth 
nearly two-thirds of a mile ; the mean breadth is over one-third of a 
mile. Its waters cover an area of nearly IJ square miles, and it drains 
an area 6| times greater, or over square miles. The maximum 
depth is 248 feet ; this occurs in the centre of the loch off the mouth of 
Allt Meallan a’ Chruidh. The mean depth is estimated at 102 feet, and 
the volume at 4091 millions of cubic feet. The breadth of the loch at 
the position of the deepest sounding is twelve times the depth. The 
shore development is 2T6, and the insulosity is nil ; Lochan Fada, like 
so many of the larger lochs, has not a single island. 
The bottom of Lochan Fada is very regular, the 50-feet and 100-feet 
areas being continuous, and extending almost from one end of the loch 
to the other. The main 150-feet area extends from west of Claona to 
the narrower part of the loch, and has a length of IJ miles; there is 8 
small 150-feet area near the south-east end of the loch. The 200-feet 
area extends from south-west of Claona to west of Allt na Botaig; its 
length is one mile, and average width 280 yards. 
The areas between the consecutive contour-lines, and the per- 
centages to the total area of the loch, are as follows: — 
0 to 50 feet 
230 acres 
25 ‘0 per cent. 
50 „ 100 ,, 
236 „ 
25-7 „ 
100,, 150 ,, 
263 „ 
28-7 
150,, 200 ,, 
100 „ 
10-8 
Over 200 ,, 
90 „ 
9-8 „ 
919 „ 
100-0 
It is unusual to observe, on proceeding from the shore into deeper 
water, an increasing area between the contour-lines drawn at regular 
intervals, as in the case of Lochan Fada, and indicates an average steep 
slope near shore. A glance at the map shows that the 50-feet contour 
follows closely the outline of the loch, and in places approaches very 
close to the shore. 
Seiche . — On July 28, beginning at 1 p.m., a well-marked seiche was 
observed in Lochan Fada in a sheltered bay at the south-west end of 
the loch; the wind was strong from the west. The amplitude was half 
an inch, and the period about 11 -6 minutes; but this oscillation was so 
broken up by two other oscillations, whose periods were about 2J 
