All rain-water pipes should deliver into the open air, and have no connection with the drains, except when they are disconnected. They should discharge their contents over a gully grating as at _a_, Fig. 5, or underneath the grating as at _b_, the ends of the pipes in both cases being in the open air. Every householder should insist upon this being carried out. But occasionally the rain-water pipes descend inside the house and there is no open yard where a disconnecting gully can be fixed. In such a case a separate drain should be laid to the nearest area or yard, and separation ensured. In laying down new drains in a house, where the rain-water pipes must descend in the interior, it will be better to provide a separate or twin drain to the nearest open-air space. Provision must be made at the roof for keeping foreign matters out of the rain-water pipes. Leaves, soot, and dirt will accumulate round the pipe orifices, and very often will cause the gutter to be flooded during a storm. The usual way to avert this is to fix over the opening of the pipe in the bottom of the gutter a galvanised open wire half-globe, or a raised cap of thick lead pierced with tolerably large holes. The cost for this is trifling, but the value is great. Whenever rain-water pipes _must_ run down the inside wall of a house, lead should be adopted. Sometimes rain-water pipes are taken down in the interior, when a very little initial study could have brought them to the exterior face of a wall--where alone they should be taken, whenever it is possible to do so. On attic roofs, and where only one side of the house can be used for the attachment of rain-water pipes, the water from one side is brought across the roof by means of a “box” gutter of wood, lined at the bottom and sides with lead or zinc, and covered with a board. This often emits a very foul smell, owing to the accumulation of decaying matter. When such guttering cannot be avoided, it should occasionally--say once a week--be carefully cleaned out. The same matters will sometimes silt up and stop the gullies, shown at the foot of the rain-water pipes (Fig. 5), hence it is equally necessary to see that these traps are cleaned out, say monthly. Rain-water pipes are often made the waste pipes of lavatories, baths, sinks, and slop-pails. When properly disconnected at the foot, in the open air, and when the top of the rain-water pipe does not terminate under a window of an inhabited room, this does not much matter; but when the court-yard is limited in area, and there is a window belonging to a living or sleeping room just overhead, where the rain from the roof delivers itself into the upright pipe, an offence will arise from the decomposing fats of soap, which form a slimy mess adhering to the interior of the pipe, that no amount of rainfall will dislodge.