ON TEMPERATURE OBSERVATIONS IN LOCH EARN. 643 
afternoon of the 24th a strong west wind began to blow, and continued for the rest of 
the month, and this wind was strong enough to start an oscillation. 
It was hoped that it would be possible to obtain fairly definite information as to 
the effect of variations in the strength of the wind, but this unfortunately was not the 
case. Some general conclusions can, however, be drawn. Thus on 5th August a wind of 
from 10 to 15 miles per hour, blowing for eight hours, was sufficient to change the 
distribution of temperature from a west wind type to an east wind type, and again, on 
14th August, a wind of this strength suddenly arising and enduring for about thirteen 
hours, nearly the period of the oscillation, was sufficient to start a small oscillation. 
Then again the curve for 9° ©. in fig. 17, from 17th to 20th August, seems to show an 
oscillation with a period which is far from uniform, but is much longer than fifteen hours. 
These oscillations are forced, as the following table will show, it being remembered* that 
at Station I. an east wind tends to raise the bottom isotherms and a west wind to lower 
them. Reference to fig. 15 will show that there were alternately calms and winds of 
moderate strength. 
Direction Ss i : Remarks on Isotherm for 
of Wind, Duration of Wind. GG ab Stations 
West. Noon on 17th—3 a.m, on 18th, Minimum about 9 p.m. on 17th. 
5 5 a.m.—9 p.m. on 18th. 5 6 p.m. on 18th. 
East. 8 a.m.—midnight on 19th, Maximum at midnight, 19th—20th. 
* 4 p.m. on 20th—6 a.m. on 21st. - about midnight, 20th—21st. 
The oscillations observed are, therefore, probably forced, while during periods of calm 
from 9 p.m. on 18th to 8 a.m. on 19th (11 hours), and from 3 am. to 4 p.m. on 20th 
(13 hours), we see the natural period for the loch trying to assert itself. 
Further examples of the effect of variations in the strength of the wind might be 
multiplied, but one other example is sufficient. We have seen that the strong wind 
which sprang up on the 24th seemed likely to start an oscillation, but this oscillation 
lasted only a very short time. ‘The wind moderated very considerably about 1 a.m. on 
the 26th, to rise again in strength at noon, and this increase in the strength of the 
wind, without any change in direction, was so timed as to damp down the oscillation 
which had just been started. 
It was, perhaps, a misfortune that during the larger portion of the month the 
oscillations were so small, but the presence of a large oscillation during the whole 
period of oscillation would have masked the smaller embroideries which the observa- 
tions show. ‘The observations were not arranged specially for the examination of these 
embroideries, and it would be desirable, for the more complete investigation of them, 
* See “Temperature of Scottish Lakes,” Bathymetrical Survey of Scottish Lochs, vol. i. p, 122. 
