Figure 13 is a diagram of the iron tank and shows the different pipe connections, comprising six 1½-inch inlet holes I I, etc., for the water from the heater to enter 6 inches from the bottom, two 1-inch holes S S for the surface spray to enter 4 inches below the top, one 5-inch bottom outlet O for emptying and circulation, and three 3-inch overflow holes W W W for the water to waste through, the upper hole 5 feet 2 inches above the bottom, and the other 6 and 12 inches below it. The overflow was originally intended to be controlled as shown in the detail, but as there was not sufficient space without interfering with the brickwork the valves were arranged as shown on the diagram. The valves are arranged so as to close either of the lower outlets, but never to close the upper one, which under all circumstances can carry off the water to a waste sink that is trapped into the sewer. In order to raise the sides of the tank above the basement floor, as shown in Fig. 10, a plate B was riveted to the side at the upper edge, and the lead lining being turned over on it, was clamped there tightly by the continuous iron bar A, screwed to the plate B.

A special steam boiler is provided on each side of the bath to keep the water heated, and acting virtually like a common range water-back, receives at the bottom cold water from the bottom of the tank, and warming it delivers it back from its upper part to a slightly higher level in the tank, thus keeping up a continual circulation.

Figure 14 is a cross-sectional diagram showing the arrangement and connections. Each pipe H is one of three connected to the inlet holes I I, etc., Fig. 13, and the two pipes C C receive the cold water circulating from the outlet O to the boilers. Ordinarily valves D, J, G G are closed and valves F F open, the circulation being continuous from boilers to tank, as indicated by the arrows, with a small amount of fresh water received and overflowing at the surface. By closing valves G G and opening D the water may be emptied into the sewer. It was originally intended to provide a special filter (E, Fig. 1) for this bath, which would receive its supply from pipe E and then discharge it through a pump into the boilers B B, thus using the same water over and over indefinitely with repeated filterings and a small addition of fresh water to compensate for waste, but this arrangement has been abandoned for the present and the entire contents of the tank are to be renewed from time to time instead.

Figure 15 shows a special device provided for skimming or flushing the top of the tank and removing automatically and continuously any scum or floating objects from the surface of the water where a large part of the impurities and foreign particles collect. At the upper end of the bath two nozzles S S deliver a fine spray of hot, cold, or tempered water above the high-water line, and so directed as to cover the surface of the water and wash all the top part gently towards the opposite end, where it slowly overflows through the waste pipe. This is intended to prevent the accumulation of scum and constantly removes the dirtiest portion of the water. The nozzles S S are supplied by a 1-inch pipe T, which is carried along the outside of the tank wall just below the cellar ceiling and delivers from a 1½ - inch mixing chamber U, which is filled from the hot and cold pipes of the regular house system with check valves D D placed so as to prevent the possibility of water from main C backing up into main H, or vice versa.

Figure 16 is a partial vertical cross-section through the side of the tank at one of the inlets I, and shows the details of lining and the method of connecting all the attached pipes. Inside and outside flanges are tightly bolted upon the iron shell to receive the screw ends of the outside pipe and a heavy brass sleeve, over which latter is slipped a tight fitting copper sleeve which is soldered firmly to the strainer-plate and slightly flanged at the other end so as to hold securely in the cement mortar which was poured behind the marble after the pipes were set.

Figure 17 shows the connections of one of the two duplicate bath boilers B B, Fig. 1 and Fig. 14. It is placed close to the tank wall W, and contains a 100-foot coil of 2-inch brass pipe which is connected with the supply and return steam pipes R and V, and receiving water from the bottom of the tank through pipe C returns it, warmer, through the three distributing pipes H H H. Fresh cold water is delivered by pipe K and by branch L to the companion boiler on the opposite side of the tank. X is a connection left for the swimming bath special filter pump. D is the Jewell filter (see Fig. 1), which is set adjacent to the boiler and which filters all the house supply. It is connected by pipes M and G to the principal cold, water main A, Fig. 1, and when in operation has valves N N open and valve O closed, but by reversing these valves the filter is cut out; valve O serving as a by-pass. Q is the crank for operating the rotating mechanism when the filter is washed, and the designation of the different valves is as follows: 1. Washout valve. 2. Wash valve. 3. Inlet valve. 4. Pure water valve. 5. Rewash valve. 6. Back-pressure valve. 7. Filling cap. 8 Overflow valve. 9. Tank inlet valve, 10. Regulating valve. To wash the filter, open valves 1 and 2, close all other valves and turn the crank on top of the filter. To filter, close all valves except 3 and 4; valve 5 should be opened only about two minutes after washing to allow a little water to filter in the sewer.

The operation of coagulating attachment is as follows: To fill the tank close valves 9 and 10, open valve 8, remove cap 7, and fill full of crystal alum, allowing the displaced water to overflow at 8, then replace cap 7. close valve 8, open valve 9 full, and adjust valve 10 to deliver the required amount of solution. The back-pressure valve 6 should be weighted sufficient to cause a shunt current as indicated by the arrows.