FOE PLEASURE AND PEOFIT. 57 



the box, and by cross bearers from side to; side if necessary. 

 This screen, or rather parts of it, may be so fitted that they can 

 be removed if necessary, i.e., just lifted out ; and perhaps this 

 is advisable more often than not. The box is fixed in the 

 bank of the pond, so that the screen at the inlet end is about 

 three or four inches below the normal height of the water in 

 the pond, which is adjusted, as I have said, by the controlling 



AN OUTLET SHELF OR LIP. 



sluice. When the box extends from pond to pond, as in Fig. 

 10, the outlet end should project into the pond somewhat, so as 

 to throw the water well out into the pond in order to guard 

 against washing away the shelving bank ; or, better still, an 

 outlet shelf or lip may be attached to it, as shown in the 

 illustration. By-the-bye, this outlet shelf or lip is advisedly 

 placed at any description of outlet, for reasons which will 

 become obvious as we go forward with our operations. In 

 action the water enters the apparatus at the arrow a, falls 



