64 FISH FARMING: 



drawings. When a mass of debris has accumulated in the 

 corner where the screen A forms an acute angle with the bank 

 at the sluice c, all that ha to be done is to 1 raise* the sluice, 

 and the consequent rush of water carries all the debris down 

 the waste channel. In action a screen thus formed almost 

 clears itself automatically, and the little debris that does cling 

 to it is easily removed by an attendant, as shown in the 

 photograph. I think it will be easily realised haw much 

 better it is to erect a screen after this manner than to adopt 

 the orthodox plan of placing it at right angles to the banks, 

 with the inevitable result that all debris coming down stream 

 is forced against it, very quickly chokes it, and in the end the 

 great pressure of debris may result in the destruction of the 

 screen, or, at least, serious injury to it. 



I cannot too strongly impress upon my readers the im- 

 portance of constructing all screens and sluices in a thoroughly 

 substantial manner, and from the very best materials ob- 

 tainable. I have already referred to the importance of fixing 

 them securely. If tha greatest possible care is not exercised 

 in this connection, disastrous results may very easily follow, 

 and then it may cost pounds and a loss of much valuable 

 time to put things right even if that be possible. True eco- 

 nomy lies in the employment of best materials and workman- 

 ship. When possible, the stream should be diverted whiJe the 

 work goes forward, and the water should not be permitted to 

 flow through or over the structure until all is complete, and, in 

 the case of cement or brick-work, not until the materials are 

 thoroughly " set " and hardened. The framework of a screen 

 should penetrate well into the banks on either side, and 

 into the bottom of the stream, Any neglect of this will surely 

 result in a tiny escape of water to commence with and ulti- 

 mately the undermining of the whole structure. Moreover, 

 the very object of the screen the prevention of fish escaping 

 is quite unattainable unless the whole structure is "tight" 

 and sound. Should any leakage occur after all possible pre- 

 cautions hafve been taken, there is only one thing to be done ; 

 no half-measures ane of the slightest use. The pond must be 



