Loch Lomond during the Autumn of 1885 319 



only eight fathoms, cold deep water is thus enabled to penetrate 

 from the Tarbet basin into the Ardlui basin, but not into the 

 Luss basin. Further, the Ardlui basin receives, for its size, a 

 much greater supply of the affluent waters from the land, so 

 that its waters in winter are probably colder than those of the 

 lake lower down. 



In accordance with the autumnal character of the distri- 

 bution, the temperature of the first ten fathoms approaches 

 uniformity at all the stations. It is highest at Ardlui, being 

 56-2, and lowest at Rowardennan, being 55-1. The steepest 

 gradients are all between 10 and 20 fathoms. They are steeper 

 in the shallow basins than in the deep ones; in the Ardlui 

 basin the average gradient is 1-53 per fathom between 10 and 

 15 fathoms. 



On 7th September the Inversnaid station was revisited, 

 and the temperatures on the gradients accurately ascertained 

 by sending thermometers to every fathom, from 13 to 17 

 inclusive, with the following result: 



Observations at Inversnaid, yth September 1885. 



The mean gradient in these four fathoms of water is r-ro^ 

 per fathom, tli.- maximum is 1-55 between 16 and 17 fathom-.. 

 It is therefore probable that tin- actual maximum gradient in 

 the Ardlui IMMII may be as much as 2 per fathom. 



Owing to a mistake, 105 fathoms of lino were paid out at 



(ulness and Inv< TMI aid m-t>ad of 100, which accounts for tin- 



irregular intervals between the thermometers at the deeper 



depths. From 30 to 70 fathoms the temperature of the water 



;htlv higher at Stuckgowan than at Inversnaid. From 



