of Edinburgh, Session 1885-86. 
409 
distribution varies at the different stations, there is little difference 
in the mean temperature of the 30 fathoms, it is higher at Row- 
creeshie than farther north. From the surface to 10 fathoms the 
highest temperatures are at the lower end of the basin, from 15 to 
30 they are nearer the upper end. At 15 fathoms the temperature 
at C ulness is lower than either north or south of it. 
5th September 1885. — All day the weather was most favourable 
for experimenting, except perhaps at Culness, when it threatened 
for a few minutes to blow and rain. Otherwise it was almost quite 
calm, with overcast sky, so that there was no overheating by the 
sun or cooling by the wind. 
Positions— No. 5. — Outer Ross Island bears S. 27° E. (true), 
distant 0*74'. 
No. 6. — Rowardennan Lodge bears N. 102° E. (true), distant 
0-43'. 
No. 7. — Stuckgowan Lodge bears S. 67° W. (true), distant 0*32' 
to 0*37'. 
No. 8. — Tarbet Pier bears S. 43° W. (true), distant 1*3'. 
No. 9. — Inversnaid Inn bears N. 34° E. (true), distant 0‘7\ 
No. 10. — Stuckindroir House bears N. 60° W. (true), distant 
0*38'. 
All the places mentioned in this paper are to be found in the 
Admiralty Chart of the lake. 
Owing to the overcast state of the sky, there is little variation in 
the temperature of the surface. Below the surface there is again 
considerable variation, but the maximum range, 2° ’25 at 15 
fathoms, is less than was observed on 18th August. The character 
of the distribution is distinctly autumnal. On 18th August the 
observations were confined to the Tarbet basin and were limited 
to 30 fathoms; to-day they extend to the three deep basins of 
the loch. The Ardlui and the Luss basins resemble each other in 
that their maximum depth is about the same — 34 fathoms ; but the 
Ardlui basin is separated from the Tarbet one by a ridge of 
probably 17 fathoms, while the ridge shutting off the Luss basin 
has a maximum depth of only 8 fathoms, cold deep water is thus 
enabled to penetrate from the Tarbet basin into the Ardlui basin, 
but not into the Luss basin. Further, the Ardlui basin receives, 
for its size, a much greater supply of the affluent waters from the 
