18 
Proceedings of the Boyal Society of Edinburgh. [Sess. 
case. Fig. 4 shows the arrangement of the isotherms in Loch Ness on 29th 
August, and fig. 14 their arrangement on 31st August 1903. 
The isotherms in fig. 14 below 44° are drawn for every tenth of a 
degree ; above that, the isotherms are drawn for every degree. It will be 
seen that there is a pretty sharp discontinuity at about 48°. The isotherms 
above that do not present any great peculiarity, nor are the isotherms 
immediately below the discontinuity layer other than would be expected. 
But the isotherms below 44° are very much disturbed, and the deeper the 
isotherm the greater its slope. This is certainly not what would be 
expected, and I think it shows that the cause of this disturbance of the 
lower isotherms is not directly to be found on the surface, but that the 
temperature distribution must be explained by some system of deep 
currents. Unfortunately, the meteorological observations for this period 
are very scant. On the 29th, 30th, and 31st August the winds were variable. 
The observations on which fig. 14 is based were taken on a Monday, and 
unfortunately no observations are available for the previous day. It is 
accordingly difficult to say what has produced the distribution shown. 
There was a strong S.W. wind blowing from the 25th to the 28th August, 
as shown from the records of the meteorological station at Fort 
Augustus. This wind may not have been general along the loch, for the 
observations from the meteorological station at Inverness do not record 
high winds at this time. 
