1906-7.] Temperature of the Fresh-water Lochs of Scotland. 15 
the year give 1'9 X 10 16 gram calories. Dr Knott states the total quantity 
of heat supplied as about 7*2 X 10 16 gram calories, or about four times the 
quantity of heat which is actually stored up. 
It was not found possible to measure directly radiation into or out of the 
loch. The temperature observations at the surface, and in the neighbour- 
hood of the Spv'ungschicht, show the presence of convection currents, and 
these currents are a very large factor in the heating and cooling of a loch. 
(Issued separately April 4, 1907.) 
