

SEPTEMBER 219 



so as the slush of London streets when 

 snow and salt have been churned by the 

 traffic. How was that? Whence had 

 the impurities come ? I surmised then, 

 and think now, that they had come with 

 the clouds from Glasgow. The furnaces 

 of that great city send into the air 

 enormous quantities of peculiarly dense 

 smoke, which is distributed to astonishing 

 distances. This I know from frequently- 

 repeated observations on a loch on the other 

 side of the hills which are the southern 

 boundary of Loch Tay. It is covered by 

 a film of soot when rain comes from the 

 south-west, where Glasgow is. The film 

 is so considerable that when the water is 

 dead-calm trout breaking the surface, not 

 with their heads only but with their 

 backs and tails also, leave in it the marks 

 of their shapes, and when wind comes, 

 making the water break in waves upon 

 the shore, the beach is blackened. Now, 

 if rain brings down some of the impurities 

 with which the clouds are charged, is it 

 not manifest that snowflakes, much larger 



