ON THE TEMPERATURE OF THE FRESH-WATER LOCHS OF SCOTLAND. 431 



were seldom very smooth — frequently, no doubt, there were instrumental variations. 

 But often the changes were demonstrably not instrumental. Fig. 1 5 is typical of a great 

 many curves. It is the record obtained with a thermometer at 100 feet on 18th and 

 19th August 1904. It shows very clearly the changes which were in progress at that 



tlveniunrtetaabioofeet. 



Fig. 15.* 



depth — that is, in the neighbourhood of the Sprungschicht. Such rapid variations are 

 quite natural, as convection currents must inevitably be set up where there are two 

 layers of water of different temperatures in contact with one another, especially so in 

 this case, as, owing to the presence of the temperature seiche, there is relative motion 

 between the two layers. 



* See footnote, page 423. 

 TEANS. EOY. SOC. EDIN., VOL. XLV. PART II. (NO. 16). 61 





