Lakes 



297 



the mean winter temperature is below that of the bottom water, 

 and generally very markedly so. 



During 1877-81 observations have been made by the 

 present writer on the distribution of temperature in lakes 

 forming part of the Caledonian Canal. The monthly mean 

 temperatures at Culloden and at Corran Ferry lighthouse, 

 which cannot differ much in climate from Loch Ness and Loch 

 Lochy respectively, have been supplied by Mr Buchan of the 

 Scottish Meteorological Society. The bottom temperatures 

 are those observed in the deepest part of the lakes, namely, 

 uo fathoms in Loch Ness, and 80 fathoms in Loch Lochy. 

 The connection between bottom temperature (as observed in 

 the second week of August) and winter temperature can be 

 judged of from the following table, where the mean temperatures 

 of October to March, and also of November to April are given : 



ii this table it is apparent that the bottom temperature. 

 ! tkes as deep as Loch Ness, is subject to considerable 

 ; from year to year, tli.it it depends on the temperature 

 <>t tin- previous winter, and that it is usually higher than that 

 teinperafi:' l:< < I >.-t \\cni t he hot toin tempei .it me 



and the mean winter temperature is greater the lower tin- 

 winter temp* tmther intcic^tin- to imtier that 

 the iin-aii wi tore "t 1878-79 was about one degree 

 hi-her than that <>! 1880-81, yet the bottom temperatures were 

 than in iSSi. .ind this JN no doubt due to 

 the the cold of 1878-79 was more continuous than 



