Thus we have the whole system of plumbing under test at the same time. Whereas, if only the soil pipe were tested, there are yet three joints to make for every fixture, which will never be under proper test. Instead of a short piece of lead waste or vent pipe being calked in, I would, if circumstances would admit, connect up the entire waste with trap attached, take out the crown vent and connect it with main ventilation pipe. Then, if the work stands a pressure of 10 pounds to the square inch, and holds up to that, it is absolutely tight beyond question, for all fixtures that go on are outside of the traps, now under test.

I consider 10 pounds air pressure ample test for ordinary plumbing. If the work stands at that pressure, it will, as a rule, stand 15 or more.

I was told at first that cast-iron soil pipe could not be calked with lead and oakum, to stand an air pressure of 10 pounds, but that theory has vanished, and good workmen have no trouble in making their work as tight as a glass bottle. The greatest danger is in calking around brass ferrules, and great care should be taken lest they " buckle in."

To test a job of plumbing with the proving apparatus, in the absence of a three-eighths nipple to connect the rubber hose to, it is necessary to havo a 2 or 4-inch iron plug with iron gasket to fit on the shoulder of the pipe in the hub "F," held in place by a clamp over the end of the hub, with a set-screw in the center to screw down on the plug. Into one side of this plug, screw in a short nipple and cock " G." To attach a hose from the pump close cock " D " and open cock E. Work the pump until the gauge C shows five pounds pressure, then close cock E. If the work is absolutely tight the indicator will remain at five pounds; if defective the indicator will go down. Now unscrew tap of ether cup B; open cock D and let the pressure off from the pipe; close cock D; put one ounce of ether in the cup; screw on cap; open cock D, to let the ether down, and at the same time begin to work the pump; close cock D; pump up to five pounds pressure, and close cock E. The ether will indicate where the leaks are, which the plumber will at once calk tight. Test the work again at 10 pounds pressure, and if the indicator stands at that the work is absolutely tight.

To test the pump, put on 10 pounds pressure, close cocks G and E, and if the indicator stands the pump is tight. A little soap and water put on the leaky joints with a brush will show the exact location of a leak by the formation of bubbles. Plumbers, architects, and builders here are perfectly satisfied with its ability to make a thorough test. That, together with its simplicity, commends it at once.