How to obtain it. -;, v . 69. 



A B is a bar of wood, underneath which is the wire or perforated 

 screen, as shewn. On the outer ends of this bar, where it 

 extends to C and D, are nailed several boards. Another cross 

 bar lies at the back of the boards just below the screen, e to f, 

 and another at the bottom of all, g to h. The whole of the wood- 

 work below the dotted line k, /, m, n, o is to be buried in the 

 bottom and banks of the raceway, and, in constructing it, the 

 screen should be made of a suitable size to fit the raceway, 

 unless it be intended to use a projecting one. In such a case 

 no screen is fitted into the opening below A B, but the projecting 

 one may be fixed to the woodwork, and instead of working in the 

 raceway it works in the pond. There is a great advantage in 

 using wood, inasmuch as joints, alterations, and repairs are easily 

 made. It is true that it is more liable to decay than stone, but it 

 lasts a long time, and is not so often damaged by frost, and it has 

 the advantage of being less expensive and more easily adapted 

 than masonry. It should always be charred, both for the sake of \ 

 preservation, and to prevent the growth of fungus ( Saprolegnia). \ 

 A screen constructed in this way will be found a very simple 

 affair, and the filling of the trench which has been dug to receive 

 it, if properly done, will render it perfectly tight and secure. If 

 the work be done in concrete or masonry the principle is still the 

 same, and will ensure safety unless it has been very clumsily 

 managed indeed. The screen can be made to slide in a groove or 

 be a fixture, as may be most desired. 



There is not much fear of the water getting round or under- 

 neath such a screen, and it will be found to be worth the labour 

 expended upon it. Fully three-fourths of those I have come 

 across which have been made in some other way have been 

 found to be useless. Once I was called to inspect a small lake 

 that had been stocked by an enterprising hotel proprietor. The 

 fishing had not improved as it should have done. We made a 

 careful survey of the water and its surroundings, and on 

 approaching the outlet one of the causes of failure was very 

 apparent. The outlet screen consisted of a big wooden frame 

 with perpendicular iron bars, but it was choked up so that no 

 water could pass through it, and instead of doing so it was escaping 

 through a hole which it had washed out round the end of the 



