302 



Lakes 



apparent from the table given below. Of the Lakes of Zurich 

 and Morat and Loch Lomond the mean temperatures are in 

 the order of their depth. Linlithgow is altogether peculiar. 

 Its high temperature, which increased steadily all the time it 

 was covered with ice, was due to chemical action amongst the 

 filth which has been allowed to accumulate at its bottom. 

 When the ice broke up the dead fish were taken away in carts. 



Table of Temperature in Frozen Lakes. 



Dr Forel gives the following particulars about the frozen 

 Swiss lakes. "The Lake of Morat has a surface of 27-4 square 

 kilometres and a maximum depth of 45 metres (147 feet) ; it 

 is 1425 feet above the sea ; and its mean latitude is 49 56' N. 

 The ice overspread its whole surface suddenly in the night of 

 the I7th to the i8th December, and it remained frozen till the 

 8th March. The Lake of Zurich has a superficies of 87-8 square 

 kilometres, a maximum depth of 468 feet and altitude of 1338 

 feet, and a mean latitude of 47 16' N. Its congelation was 

 gradual, and not sudden like that of the Lake of Morat. First 

 the upper part of the lake was covered with ice between Manne- 



