DRAINS

must be in good order if the house and the town aro to be healthy. The chief points in good drains are that they are (1) water tight, (2) well ventilated, (3) without direct connection betweon those carrying ty eg those carrying waste from baths, washbasins and the like, (4) well flushed. (1) In order to be water-tight the drain should be made of iron, but owing to the expense thi involves they are generally made of earthenware. The joints between the earthenware pipes were formerly filled only with clay, but as this was proved to cause = ff in @ very short time, they have recently been ‘ecig-red led with cement, which is much better, but which is apt to expand and produce leaks by bursting the joint; long iron pipes with lead joints is the most water-tight system invented so far. Next the bed in which the pipes aro laid must not be liable to sink or the joints will give, even though firmly cemented. For this purpose care is taken not to sink the original trenches deeper than nece ary, as any filling in with fresh earth promotes subsequent sagging. At times drains are laid in beds of concrete, though this is not as efficient as at first hoped, owing to cracking often taking place. (2) The ventilation of the drains must bo very a or sewer gas will find its way into the house in spite of the most careful cele to prevent it. (3) The waste pipes from baths, etc., should never open directly into tho sewer, even though the connection is guarded by a pe They ppt their water into an open receiver or gully placed outside the house, and the gully should be connected with the sewer. Then if any sewer es escapes from tho Ly it will pa off in the opon air without being conducted are the house. In tho same way the water used to flush tho water-closet should not come direct from the chief cistern, but from a special smal) cistern, the water of which is nover used for drinking purposes. By this arrangement if sewer gas pa into the dual cistern, it will be absorbed by the water in it without pa ing on to the chief re | water cistern. (4) In order that a drain may be well ’ not only must an ample supply of water pa down it, but 4 the drain must be laid at pa an incline thet the flow is: sufficiently rapid, and must be fairly narrow aid as straight es po ible for the same reason; and again, fri >tion must be reduced by making the internal surface smoc_h. By these means the accumulation of filth is reduced to a minimum. Testing the drains is best done by plugging the outlet of the br eee drain at the nearest th or and then poor, Be with water from the water-closet. If a leak is present, water soon sinks, and if many leaks are present it may not be po ible to fill the drain at all. Suspected leaks may also be tested by pouring down strong oil of —, or asaf@tid a in hot water, whilst a second person ip the room below determines whether the odour escapes or not, but this method is not so thorough as the former test, though more easily performed by the householder. to: Typhoid Fever, Diphtheria, Water Closets—Sewage Di ] [s. 355]