Water-closets are now most generally con structed of glazed earthenware, some are made of the finest bona china and others again are made of cast-iron with a china finish. The old-styled closed plumbing has given way to the most modern sanitary appliances, and open work is generally to be found even in the poor est dwellings, because of its cleanliness, health fulness and ease of access to repair.
The next part of the general sanitary sys tem to be considered is the arrangement of pipes and appliances which connect the basins, sinks and water-closets with the general sewer. Ventilation is one of the most important sub jects which the sanitary plumber must under stand. How to prevent gases arising from sewers — for where there are sewers there is sure to be sewer-gas — and how to prevent the air in a room from becoming foul, have been constant sources of trouble to the modern sani tary plumber, and that he has solved these problems has probably resulted in more benefit and insured the public against more harm from diseases attendant upon these evils than any other one thing. It is an indisputable fact that the wise and exact observance of these sani tary laws has been a potent factor in materially reducing the death rate in our larger .cities.
In this system of pipes the most important object is to prevent the air within them from gaining access to the building. This is most generally done by means of a trap or depres sion in the pipe, or by making the internal pipes gas-tight. The inverted siphon, sealed by water lying in the bend, is probably the best form of trap. Fresh air should have free access to the pipes, the air of the sewer should be shut off from that of the nines within the house and fouled water should be immediately and completely removed from the vicinity of the building. The ventilation largely affects the methods of connecting the main drain with the soil-pipes. The most general and easiest method of ventilating the soil-pipes is to extend the drain pipe to a point above the roof, and through this the current of air, which comes in at the manholes in the street and passes along the street sewers, flows upward and out. The method is most effective where the street sewers are constructed on the °separate° sys tem, but where the street sewers are built on the `combined" plan, it is preferable to have a trap on the house sewer in connection with the fresh air inlet, because of the fact that the foul air currents are thus diverted from the interior pipes and a current of fresh air is forced up ward through the soil and ventilating pipe.
Waste pipes should be of lead, though some times cast or wrought-iron is preferable because Of the large diameter required and the soil; waste and ventilating pipes should be exposed as much as possible for purposes of inspection or repair. The main house drain and the soil
pipe should be of heavy cast-iron with lead calked joints, and all iron pipes and fittings should be coated with coal-pitch varnish, both inside and outside. If plumbing work be car ried out on the ideas set forth, with proper traps, light, ventilation, simplicity, accessibility, good workmanship and a high grade of material throughout the public health will properly be insured against the ravages of disease so com mon before the improved appliances came into vogue.
Another distinct division of the plumbing trade is the carrying of steam in pipes through out a building. Pnor to 1840 and even as late as the Civil War, the growth of steam heating had not assumed any great proportions. Eng lish inventors had made many attempts at steam heating by means of small pipes connected with boilers, on the theory that this would create a high temperature. But this soon gave way to the low pressure system because of the fact that there was little or no wear upon the ap paratus, and the generation of the low pressure saved fuel. Joseph Nason, of New York, and J. J. Walworth, of Boston, were largely instru mental in the earlier development of the indus try. Boilers were first used, but these were quickly followed by radiators constructed of wrought-iron tubes, both vertical and horizon tal. In 1865 the manufacturers began to make heating boilers and radiators from cast-iron, and the manufacture of steam and hot-water furnaces has become an industry of great im portance. The development of the modern office building has in a large measure added to the success of this branch of the trade, for it is in these that this system of heating is car ried to its greatest degree of perfection. The boilers used in these buildings are of wrought iron or steel, because the running of elevators, electric lights and pumps, necessitates that a high pressure be maintained on the boiler.
The industry is now so complex, drawing its supplies from several lines of manufacture, and consisting mainly of contracting work, that ac curate statistics of its extent cannot be com piled. Consult Starbuck. R. M., 'Modern Plumbing Illustrated) (1915) ; and Gerhard, 'Sanitary Engineering of Buildings' (1915).
See BOILER ; BATH ; DRAINAGE; PUBLIC HEALTH ; SANITARY ENGINEERIINgi SANITARY SCIENCE; VALVES; WARET: ITS KELATION TO DISEASE, ETC.