Loch Lomond during the Autumn of 1885 331 



16 fathoms occurs in the last days of September. It is probable 

 that temperature at the bottom (35 fathoms) was about its 

 maximum on I5th October. 



The points of intersection of the curves indicate depths 

 where the temperature of the water was found to be the same 

 on both days. Although the temperature of the water at this 

 depth has risen and fallen in the interval, it has returned to 

 the same thermal state at the end of the interval as at the 

 beginning. In Table IX the distribution of heat in the water 

 above and below these points is indicated for the different pairs 

 of dates. As a linear heat unit is required the fathom-degree* 

 has been adopted. 



From the table we see that between the 5th and 22nd 

 September the water as a whole has lost as much heat as it 

 has gained, so that all the heat that the layer above the inter- 

 section at 13-5 fathoms has lost appears in the deeper water 

 below the intersection. On an average over the whole period, 

 no heat has been dissipated to the atmosphere. This, of 

 course, is only true on an average ; for during the first portion 

 of the period the water has been receiving heat, and during 

 the second portion it has been dissipating it at the surface. 

 During this interval the heat passed downwards to the deeper 

 layers has been at the rate of 1-94 fathom-degrees per day. 

 Between the 22nd September and I5th October the amount of 

 heat transmitted downwards has been 14 per cent, of the total 

 loss above the intersection. The heat dissipated per day to 

 the atmosphere is 2-61 units, and that passed downwards 0*61 

 unit. The curve of 141)1 November does not cut that of 

 i5th October, and the loss of heat is at the rate of 3-2 units 

 per day, all of which has gone out into the atmosphere. On 

 the j ;rd November 1876 I found the water of the Luss basin 

 to have ;i uniform temp, r.iture 47-8 from ^urt.ire to bottom. 

 In the year 1876, therefore, the water hid a temperature 

 1-5 higher on the . vember than it has in 1885 on 



I4th November, or nine days earlier. For the same date the 



1 I : i ! It thr fathom has a 



: then tin- 

 same as the ordinary heat unit. Se 



