14 
Proceedings of the Royal Society of Edinburgh. [Sess. 
IV. — The Temperature of the Fresh- water Lochs of Scotland, 
with special reference to Loch Ness. By E. M. Wedder- 
burn, M.A. Communicated by Sir John Murray, K.C.B. 
(Read May 28, 1906. MS. received February 5, 1907.) 
(Abstract.) 
The communication of which this is an abstract has been published in the 
Society’s Transactions (Vol. XLV. Part II. No. 16), with an appendix 
containing observations made in Loch Ness by members of the Scottish 
Lake Survey and of the Order of Saint Benedict at Fort Augustus. 
Numerous temperature observations have been made in the lochs which 
have been surveyed by the Scottish Lake Survey, and these observations 
are published in the Lake Survey Reports appearing in the Geographical 
Journal. A great number of observations were made in Loch Ness between 
July 1903 and May 1905. Generalising from these observations, it appears 
that, under conditions similar to those which exist in Loch Ness, a loch 
gains heat gradually throughout its whole depth until July or August. 
In August or September it begins to lose heat. There appears at the 
surface a gradually increasing layer of water of uniform temperature, and 
while the surface temperature decreases, the total quantity of heat in the 
loch may for a time increase, owing to various mixing influences heating 
the waters at considerable depths. This layer of water of uniform tem- 
perature, while decreasing in temperature increases in depth, and at the 
time when the quantity of heat in the loch is least, the temperature of 
the loch is nearly uniform throughout. 
When this surface layer becomes distinct, i.e. when the Sprungschicht 
appears, the temperature seiche described by Mr Watson * becomes evident. 
The observations now available confirm Mr Watson’s general conclusions. 
Observations made at the two ends of Loch Ness show opposition between 
the phases of the seiche, and a binodal seiche is also apparent. The observed 
value for these temperature seiches agrees well with values arrived at by 
rough calculations. Records obtained by the Callendar Electrical Recorder 
also support strongly the theory of the temperature seiche. 
Rough calculations of the amount of heat which Loch Ness gains during 
* Geographical Journal , October 1904. 
