FOB PLEASURE AND PROFIT. 21 



protect the eggs from being swept aiway by the first flood 

 and floods pretty generally occur during the season of incubar 

 tion of otherwise destroyed. In Fig. 6 1 suppose* a stream 

 in the hills is confined between bigh banks ; that the levels of 

 the surrounding countryside do not permit of a channel being 

 cut, as shown, in connection with my remarks on how to con- 

 struct ponds in hilly districts in the chapter on that subject, 

 and that consequently the redds must be protected absolutely 

 in the bed of the river itself. 



Choose a favourable spot, if possible where the current will 

 naturally be inclined to flow towards the channel c c, and 

 form a substantial breakwater B B B, which must be sufficiently 

 high to protect the redds from any possible flood. Above the 

 dotted line D the bed of the stream, and consequent depth of 

 water, must b arranged so as to ensure a constant supply of 

 water flowing through the- " underground " supply channels 

 E E E (which are made and fixed as explained in Fig. 4 and 

 Fig. 5), when, the water is at its lowest level. Below the 

 dotted line D the channel c c must be well deepened, and the 

 adjoining bank may, if possible, be encroached upon; the 

 material so obtained being used in the construction of the 

 breakwater. These precautions become necessary in order to 

 facilitate the passage of a great push of waiter through the 

 channel c c. It will be noticed that the screen F is, of neces- 

 sity in, this case, cleared from debris by a sluice at the end 

 nearest the bank, and not by a channel cut into the bank, as 

 in Fig. 2 and Fig. 3. The redds are marked at A. The falls 

 to them should be arranged to permit of exttfai deep falls at 

 j and K, especially at J ; this to guard against the flood water 

 flowing back on the lower redds. If possible, the fall of the 

 river from the point G to the point H should exceed the pro- 

 bable rise of water ait flood time ; if this is so, then you need 

 fear nothing from flood water flowing back over the redds, 

 but if it be less then you are sure to get some sediment on the 

 eggs after the flood subsides. This is certainly not in your 

 favour ; but it can be dealt with, if it does not occur in too ex- 

 aggerated a form, in the manner explained at the end of this 



