The following inquiry has suggested a description of an automatic arrangement for turning off the gas-supply to a hot-air pumping-engine, recently arranged by Messrs. Pasco & Palmer, plumbers, of this city:

Q. Can you let us know whether there is any device whereby the gas-supply to the caloric pumping-engines can be shut down to a mere spark when the water-tank is full, and turned on again when the tank is empty, automatically?

A. The device represented in the drawing does not do what our correspondent asks for, which would seem to be a much more difficult thing to accomplish than to simply turn off the gas, since the hot-air pump in most common use is a single-crank engine, requiring the proper adjustment of the piston before starting.

The following 'is an explanation of the arrangement shown in the sketch: On the gas-pipe d supplying the engine is a stop-cock, on which a grooved iron wheel takes the place of a handle. A chain, attached to a pin at the point a in the circumference of the wheel, passes over the top and supports a small tin pail, c. The end of the tank tell-tale e is brought over the pail, so that the weight of the water discharged into it will cause the pail to fall, thus turning the wheel and closing the valve on the gas-pipe. Before starting the pump again the pail is emptied. The large pipe /, shown on the right hand, is an air-chamber on the suction-pipe to supplement the smaller one attached to the pump. The stop-cock g, at its foot, is for removing all the water from it.

Figure 57.

There are other devices for the same purpose, such as a small tank under the tell-tale, containing a float connected with the valve on the gas-pipe, but the arrangement shown above is simpler than anything we have seen for the purpose.