262 SALMONIA. 



in a part of its course, below Ischel. I was 

 once at that place, when the thunder storm 

 of a night having washed the dust of the 

 roads into the river, it was extremely turbid 

 from Ischel to the Traun see. It rendered 

 the upper part of this large lake coloured; 

 but notwithstanding this, the river came 

 from the lower part of it perfectly clear, 

 and I caught fish in it there with a fly, 

 which at its entrance into the lake was quite 

 impossible. 



Poiet. — You, Halieus, must certainly 

 have considered the causes which produce 

 the colours of waters. The streams of our 

 own island are of a very different colour from 

 these mountain rivers, and why should the 

 same element or substance assume such a 

 variety of tints. 



Hal. — I certainly have often thought 

 upon the subject, and I have made some 

 observations and one experiment in relation 

 to it, I will give you my opinion, with 

 pleasure, and as far as I know, they have 

 not been brought forward in any of the 

 works on the properties of water, or on its 



