FOR PLEASURE AND PROFIT. 129 



01 time. The prevention of such disaster is ai simple matter, 

 all that is required being proper attention to the screens. 

 But I may well emphasise the importance of keeping the 

 screens below the surface of the box, and I show them in this 

 position in the next drawings. Fig. 29 is ai section acro.ss the 

 filtering box at one of the screens 1 , and Fig. 30 is a section 

 showing the method of fixing the slats at the back and front 

 of the screen so that they form a groove on each side of tLe 

 box. A is the flannel screen, B is the framework of the screen, 

 c is the slat, D is the lid of the box, E isi the framework of the 

 box, and F is the space left for the water to flow over the 

 screens in casei of auiy of them becoming clogged with sedi- 

 menb. It should be noticed that the bottom of the frame of 

 the screen is bevelled, so that it fits snug and accurately to 

 the bottom of the box. Screens fixed in this manner arc 

 never any cause of trouble by floating. They may be quite 

 easily cleaned by allowing them to get dry, when the sediment 

 can be lightly brushed or dusted off. For 1 this reason, and 

 for others which I have previously explained, a few spare 

 screens are very useful ; indeed 1 , they are necessary. If the 

 water is very full of sediment of a, somewhat coarse nature, 

 the first and second screens may be of fine wire gauze, but, 

 as a rule, the flannel will be found to be ail that is necessary. 

 The screen next the outlet should b& removed as seldom as 

 possible, and even then a duplicate should be ready to put 

 into position immediately. This screen should always re- 

 main in position while the water in the filtering box is being 

 lowered by means of the plug4iole, but the other screens 

 should be removed, and, of course, the main supply shut off. 

 One other caution : Let the plug-hole be amply big, so that 

 the process of lowering the water in the box is rapidly 

 effected. 



Fig. 31 shows ai useful form of outlet spout for the supply 

 to the filtering box, for the filtering box, and for th& distri- 

 buting box; and Fig. 32 is ai plan of the spout. It is fitted 

 with ai small hand sluice, of which there must be a number, 

 with different size holes at c to regulate the quantity of water 



K 



