156 
BATHYMETKICAL SURVEY OF 
Loch Bhradain (see Plate LVIII.). — Loch Bhradain (or Vrotten) lies 
midway between Loch an Duin and Loch an t-Seilich, receiving the 
outflow from the former and draining into the latter. Trending in a 
south-west and north-east direction, it exceeds half a mile in length, with 
a maximum breadth of one-fifth of a mile, covering an area of about 53 
acres, and draining an area of 7 square miles, including Loch an Duin. 
The basin is simple, with a maximum depth of 41 feet, recorded near the 
middle of the wide northern part of the loch. The volume of water is 
estimated at 34 million cubic feet, and the mean depth at 15 feet. The 
loch was surveyed on May 18, 1904, but the elevation could not be deter- 
mined; from spot-levels it was estimated to be about 1452 feet above the 
sea. The surface temperature was 43°*4 Fahr. 
Loch an t-Seilich (see Plate LVIII.) lies about four miles to the east 
of Loch na Cuaich, flanked on the west by Bogha-cloiche (2945 feet) and 
on the east by Mullach Coire nan Dearcag (2846 feet). It is the longest 
of the Spey lochs, but is inferior in superficial area to Loch Morlich and 
Loch Insh. In outline the loch is sub-rectangular, trending nearly north 
and south, and is 1^ miles in length, with a maximum breadth of nearly 
half a mile at the southern end, whence it narrows slightly towards the 
north, the mean breadth being one-third of a mile. The superficial area is 
about 249 acres, and the area draining into it is nearly 25 square miles, 
including Lochs an Duin and Bhradain. The maximum depth of 98 feet 
was observed in two places, separated by shallower water: (1) nearly half 
a mile from the northern end towards the eastern shore, and (2) over a 
quarter of a mile from the southern end in a central position. The 
volume of water is estimated at 448 millions of cubic feet, and the mean 
depth at over 41 feet. The floor of the loch is somewhat irregular, show- 
ing slight undulations both longitudinally and transversely, and the 
coutour-lines are sinuous in places ; the deep water approaches very close 
to the southern end, a sounding in 75 feet being recorded less than a 
hundred yards from the southern shore. The loch was surveyed on May 
17, 1904, but the elevation could not be determined ; from spot-levels it 
was estimated to be about 1390 feet above the sea. Temperatures taken 
in the southern deep basin showed a range of only 1°*7 Fahr. from surface 
to bottom, the readings being — 
Surface 
10 feet 
20 „ 
40 ,, 
60 „ 
80 „ 
440-0 Fahr. 
43°-5 „ 
43°*1 „ 
42°-7 „ 
42°-6 „ 
42°-3 ,, 
Loch Insh (see Plate LIX.) is situated about 5 miles to the north- 
east of Kingussie, surrounded by woods (see Fig. 33), and may almost be 
regarded as a large expansion of the river Spey. Though containing the 
