The system described in these pages is intended to prevent in a measure this excavating, and to enable a person above the ground to determine the number, capacity, and state of the drains underneath the surface, as well as to more readily discover any imperfections in soil-pipes and sanitary fittings. When sewers are laid to a town or district, it is the practice of the authorities to let the work by tender, the lowest tender being oftentimes accepted; consequently it is in the interest of the contractor to get the work done as quickly and cheaply as possible. It is impossible for the engineer, or clerk of works, to see the whole of the work done, and the result is that a large quantity of bricks which form the sewer are not properly bedded. Liquid sewage finds its way through the joints of the brickwork and percolates through the soil, in some cases to a very considerable distance, contaminating the water it mixes with on its course, and oftentimes it forms a putrid mass under the basement of buildings which happen to be of a lower level than the sewers. To prevent this, a clause should be inserted in the contract that each length of drain or sewer should be tested by atmospheric pressure, say 5 lb. to a square inch. The top of the sewer should be as tight as the bottom to prevent any gas escaping through the sandy soil or rubble which may be filled in around the sewers or drains. Leaky sewers and badly-jointed pipes under the soil should never be allowed, yet the danger is not so great in them as in those pipes laid above the ground. Joints to these pipes so often leak that without testing them thoroughly when laid, one leaky joint would cause an unpleasant odour in a building for years without its source being discovered. The reason of this is, that the current of air passes through buildings in a thousand different ways. I have known a sickly odour to come from a cupboard on the first floor of the wing of a building some 60 feet from any soil-pipe or grating; one case in particular, that of a nursery cupboard. This occurred through a leaky soil-pipe from the closet in the basement of the building. From the planning of the building the chimney near the cupboard had the greatest draught of air in the house, and the air which supplied this chimney came principally from the basement. The sewer gas from the leaky joint, being of a heavier gravity than the atmosphere of the house, was carried along the floor unobserved to this particular room, filling at night, when the fire was not burning, this cupboard, which contained linen, and this held the impurities given off from the leaky joint in the pipe. Many cases of a similar nature could be mentioned, where families will never recover the loss sustained by them through similar leaky joints in the soil-pipes.