644 MR E. M. WEDDERBURN 
to observe at closer intervals of time, and also at shorter distances along the loch. 
Figs. 7-11 show that though the temperature-depth curves follow a definite type 
there are many irregularities —double discontinuities and the like—which can only be 
investigated in this way, and for the elucidation of which recording instruments would 
be invaluable. Towards the end of the month an effort was made, by concentrating 
the observers at Stations III. and V., to follow some of these smaller variations, but 
these small variations seemed at that time to have almost disappeared, and a number 
of accidents occurred which made this series of observations of little value. 
Before work was discontinued, observations were made at the point marked VI. on 
the sketch map simultaneously with observations at Station V., during a strong west 
wind—so strong that both boats dragged their anchors. These observations were made 
from 6 a.m. to 6 p.m., on 29th August, during which a small oscillation was in progress 
The depth of water at Station VI. was only about 12 metres, and always about 2 metres 
or so above the bottom there was a sudden fall in temperature, the temperature found 
at 12 metres being the same as was found at about 24 metres at Station V. Whether 
this was due to the high wind or not, cannot be said, as similar observations were not 
made during a calm. It is very probable, however, that it was the result of the high 
wind, and indicated that warm surface water was being forced downwards by the 
high wind. 
Viewed as a whole, the results of the investigation may be summarised as 
follows :-— 3 
It has been proved beyond all possible doubt that what we have called Temperature 
Seiches do exist, and that they are truly of the nature of a standing boundary wave. 
Examples of the effect of winds, both in starting and in damping oscillations already 
in progress, have been given, with an indication that even a wind of very modera e 
strength will start oscillations, and examples of oscillations foreed by wind have also 
been obtained. ‘ 
The observations suggest the lines on which the investigation of lake temperatures 
may most profitably proceed in the future, viz. the investigation of the short-period 
oscillations, analogous to “vibrations” at the free surface of the loch, most of them 
probably due to travelling boundary waves, some due to standing waves of high 
nodality, and some perhaps due to transverse oscillations. 
Before passing to the more technical part of this paper, | should like to record my 
indebtedness to all the observers who assisted in the work, and particularly to those in 
charge of the various stations. But for the energy with which they all carried on the 
work; which was frequently of an uninteresting as well as of an arduous and uncomfort- 
able nature, the expedition would have been a failure. I should also like to acknowledge 
the courtesy shown by proprietors along the loch shore for facilities for landing b 
ete.; also to many of those in the district who in various ways, such as rescuing 
shipwrecked observers, helped on the work. | 
