PROCEEDINGS OF SECTION D. 293 



The wire-basket, when attached to the end of the fluming, projects 

 (as shown in the diagram) from 6 inches to 12 inches beyond the end, 

 according to the width. As large a straining surface as practicable 

 is given, so as to avoid any suction against the screen, and so as to give 

 even the youngest fry a chance of swimming quite close to the screen 

 without their being drawn to its surface. The latter not infrequently 

 happens where the screen is at the surface of the water, particularly 

 where, as a result of partial clogging, the water has banked up a little. 

 On account of the natural buoyancy of the wood used in the con- 

 struction of the outflow-boxes it is necessary to weight them slightly so 

 that they may remain in position, otherwise they will have to be 

 wedged in. For this purpose flat galvanized iron straps may be put 

 Tound the sides, or else the cleats themselves may be of galvanized 

 iron. 



Some time before being used, the whole contrivance is given two 

 or three coats of patent asphaltum paint, so as to render the wood 

 non-absorbent and readily cleaned. This asphaltum should be renewed 

 from time to time. 



It is advisable to have a spare one made for each pond, so that 

 one may be taken out now and again, say, to be cleaned and thoroughly 

 dried and re-asphalted. 



For cleaning while in position, an ordinary tar-brush set obliquely 

 on the end of a long handle will be found of service. 



I spoke of the great straining surface offered by the use of the 

 wire-basket attached to the lower end of the outflow-box, as compared 

 with the ordinary small surface screen. I need only take No. 1 pond 

 at Prospect as an instance. Under old conditions the straining 

 surface at the outlet was equal to about 15 inches by 1 inch — equal to 

 about '10 of a square foot — always providing the water was running 

 through freely (which through partial temporary clogging would 

 frequently not be the case). With the use of the outflow-box and 

 without increasing the actual width of the outflow, the straining surface 

 is increased to 4*90 square feet ; or 49 times the old straining surface. 

 The advantage is obvious. 



Though the contrivance above described is so very simple, its 

 eSect is so good that I have deemed it worth while to describe it for the 

 benefit of those who are possessed of fish-ponds in which there is an 

 insufficient circulation of water. Added water circulation and 

 oxygenation mean increased stocking capacity of course, and often an 

 insufficient water supply is blamed for what sidould be laid at the door 

 •of imperfect circulation. 



These outflow-boxes might be made of thin metal. If a rectangular 

 pond is being specially constructed and it is desired to incorporate the 

 principle of drawing ofi the water from the bottom, it v\^ould be better 

 to have the outflow-boxes let in to the end of the pond, so that the end 

 might present a " flush " surface. 



