Loch Lomond during the Autumn of 1885 335 



i8th August and the 5th September, an interval of 18 days, 

 during which the temperature of the layer immediately at the 

 surface had begun to fall, five times as much heat was conveyed 

 downwards as was dissipated from the surface. Between the 

 dates 5th September and 22nd September the two quantiti-- 

 almost exactly balance one another. Between 22nd September 

 and i5th October the amount transmitted downwards is only 

 half what leaves the surface; and between the I5th October 

 and 1 4th November the amount transmitted downwards is 

 quite insignificant not more than 4 per cent, of what 

 escapes to the air. The activity in the heat exchange has 

 been greatest between 22nd September and i5th October when 

 it has been dissipated at the surface at the rate of 3-74 fathom- 

 degrees, and conveyed downwards at the rate of 2 fathom- 

 degrees per day. The crest of the heat wave passes from surface 

 to bottom in about three months, the height of it decreasing 

 very rapidly as the depth increases. 



Dates of Maximum Temperature at Different Depths. The 

 intersections of the curves give, as above shown, an indication 

 of the date of maximum temperature at the particular depth. 

 In Table XII will be found the depths corresponding to the 



TABLE XII. 



prim -ip.il intersections and the mean dates. The actual dates 

 of maximum temperature \\ill always be a day or t\\" 

 than the mean dates. The number of observations is too small 

 to enable us to say what the maximum temporal these 



en. 

 As t! in of 1885 has been a cold one, the above mean 



