XCVIt 



surface below the water level— tlie purpose being to in- 

 sure tliem against being clogged by the piling up of 

 successive layers of drift, wMcli otherwise would inevi- 

 tably be occasioned by the gradual rise of the water 

 consequent upon its obstructed flow. The arrangement 

 suggested will always afford a free exit to the water 

 beneath the mass of accumulated floating rubbish. 



The general details of outlet, A, are clearly indica- 

 ted in the views given. The screens s. s. s. — as well 

 as those of the "overflow" — are disposed in a suita- 

 ble frame work, and should slide easily in their re- 

 spective grooves, so that they may be readily removed,. 

 cleaned and replaced. An additional set of such grooves 

 are provided at this outlet, as will be seen by reference 

 to the plate ; and these latter, which are innermost in 

 point of position, are furnished, instead of screens, with 

 solid planks g. g. g. — the edges of which are neatly fltted 

 to each other, so as to render their joints water tight, or- 

 as nearly so as possible. The upper edge of each plank,, 

 again is provided with staples or eyes— 3/. ./. ,/. — through 

 which the hook, ^, may be readily passed in order to lift 

 the plank from the frame. When the X3lanks are in posi- 

 tion these eyes are received into corresponding slots, n. n. ,. 

 in the lower edge of the planks immediately above them,, 

 so as to allow the planks to flt closely together. 



The purpose of this fourth, and solid, screen is to ena- 

 ble the culturist to lower the water in the pond, whenever 

 it becomes necessary to do so, by drawing it from either 

 the surface or the bottom, as may be deemed most advis- 

 able. To draw it from the surface only, it will simply 

 be necessary to open the valve c ; and to remove the 

 planks in succession, as the water subsides. While to 

 draw from the bottom will require all the planks to be 

 first removed ; and the valve to be opened when this has 

 been done. 



In addition to the valve c, the drain-pipe, P, may be 

 provided, at m., with a clog or strainer, to guard it 



