Withy. — On Sanitation and Ventilation. 469 



scribed are brought together, and the separate parts named, 

 on Plate XLIX., fig. 1. 



Waste-water Pipes. 

 These are required to discharge the contents of baths, 

 lavatories, urinals, and sinks. They should be kept entirely 

 clear from connection with the soil-pipe. This may seem 

 superfluous, in the opinion of some who have followed me in 

 the description of a modern soil-pipe, however desirable it 

 might be to separate them from one of the old style. But we 

 must bear in mind that plumbers are mortal like ourselves, 

 and do not always perfectly execute what has been well de- 

 signed. We must also remember that materials always decay, 

 and may be damaged by accidents ; and, further, that the 

 best thoroughfares sometimes get blocked. Danger may arise 

 from any of these contingencies happening, and it is always 

 well to make assurance doubly sure, especially when the cost 

 of doing so is not great. There can be no danger in carrying 

 several of these pipes into one, provided the area of the main 

 pipe is made sufficient. There should always be a trap, formed 

 as an S bend, in the pipe pretty close up to each vessel to be 

 discharged. At the lowest part of the bend of the trap a 

 brass screw-plug should be fitted for the purpose of cleaning 

 out the sediment, and for readily getting at any obstruction. 

 Plate XLVIIL, fig. 4, shows such a bend, with screw-plug. A 

 grating should be fitted over the top of the pipe to detain any 

 pieces of refuse which may find their way into the vessel. In 

 order that the clearway of the aperture shall not be too much 

 reduced by this, the pipe should be widened out at the top to 

 take a grating rather larger in diameter. The waste-pipe 

 should then be carried through the wall and made to discharge 

 in the open air above an earthenware sink-trap fitted with a 

 galvanised-iron loose grating. This will cut off all connection 

 with the drain, fresh air will flow freely into the pipe, and the 

 waste w T ill be discharged more quickly, because the vent is 

 not choked as it would be if it opened out into the water of 

 another trap. Cast-iron traps, of whatever form, are objec- 

 tionable, owing to their liability to become perforated by cor- 

 rosion, and owing to the roughness of their inner surfaces 

 compared with those made of lead or glazed earthenw T are. 

 Where a good deal of cooking is carried on it will be advisable 

 to have the outside trap fitted with a removable tray which 

 shall retain the grease : such a trap is shown on Plate 

 XLVIIL, fig. 5. In the absence of such a provision every 

 trap should be made self-cleansing — i.e., constructed without 

 corners, pockets, or rough places. The size of traps can only 

 be determined by the amount of waste which they are ex- 

 pected to carry off. 



