10. Wash basins are either round or oval in shape. The ova/ basin affords more room for the free use of the arms than a round one of the same capacity, and is, therefore, preferred.

Basins are measured over the outside of the top flange. Round basins vary in diameter from 12 to 16 inches. Oval basins are usually made in three sizes, 17 in. X14 in., 19 in. X15 in., and 21 in. Xl6 in. The word bowl is now often used instead of basin. It refers only to that part of the fixture which holds the water.

Basins are made of iron, galvanized or enameled, and also of porcelain. The porcelain basins are made in plain white color, or they are decorated to any degree of elegance that may be desired. Wash basins are constructed in many ways. In the commonest variety, the bowl is separate from the slab or top, and the splash plate or back is also separate from the slab.

In other varieties, the bowl, top, and back are made in one piece of metal or porcelain.

11. Bowls are made with and without overflows, and the overflows are of several varieties. In Fig. 7 the overflow consists of a strainer A and a nozzle, or horn, B, to which a waste pipe is attached by a cemented slip joint, or by a rubber cone connection. The latter is preferable.

Fig. 7.

In Fig. 8 the overflow duct a, which is molded on the basin, leads into the waste outlet b through holes c in the connection under the rubber plug d.

In Fig. 9 the porcelain bowl is constructed with a recess a to contain a combined standing overflow and waste plug b. The base of the waste plug is perforated and forms a good strainer, which can easily be cleaned by lifting out the entire waste plug and overflow arrangement. The top of the plug b slides in a guide which is secured to the marble top c by a lockout d. The standing waste is suspended by a bayonet catch, as shown at e.

Fig. 8.

Fig. 9.

In Fig. 10, the bowl c is made plain without even a stopper, and has a strainer only. The stopper and standing overflow are contained in the tube a. The surplus water escapes through the holes b. Bowls are also made with flushing rims, and the faucets are placed below the top, having only the handles in sight. The rim of the bowl is thus freed from all obstructions, and the hands of the bather cannot be injured by the nozzles of the faucets.

Fig. 10.

Wash basins are supported upon substantial wall brackets, or upon metal frames or pedestals. They should never be cased in with cabinet work, because such enclosures cannot be kept clean, and vermin will find lodgment in the crevices of the woodwork.

12. The slab, or top, should have a raised rim around its entire perimeter, so that splashes of water will drain back into the bowl. The holes for basin cocks and other attachments should also be surrounded by raised rims, for the same purpose. The holes for ordinary basin cocks should be made square to receive the square shank of the cock, and thus prevent it from turning.

The proper height of the top of the slab from the floor varies from 30 to 31 1/2 inches, the former being generally satisfactory.

The basin cocks should be attached to the slab with a lead washer between the marble slab and the nut underneath. The chain stay should be fastened in the same manner. The cocks should be set in plaster of Paris.

The connection between the waste pipe and the discharge outlet of the basin is commonly made by means of a screw coupling, as shown in Fig. 8. Great care must be exercised in screwing up this joint because the bowl is very liable to crack or break at this point. A thick gasket of soft rubber should be used between the lockout e and the porcelain.

The space between the splash plates, or back, and the wall should be completely filled with plaster of Paris, so that no crevice or hole is left for vermin.