Joseph C. Strode, of East Bradford, Pa., has taken measures to secure a patent for improvements in the above. The inventor forms the driving pipe of a peculiar shape, as it describes such a course that it enables a greater quantity of water to be raised by a machine of a given size than can be raised with a driving pipe formed in any other manner. It will moreover, cause a greater re-action of the water to take place after the closing of the valves leading to the air-chamber, and thus more perfectly ensure the opening of the discharge valve. Besides this improvement, there is an arrangement for regulating the closing of the discharge valve, so as to prevent the violent shock which it experiences each time it closes. This is remedied by causing the part of the valve below the seat, to enter a recess, and thus make a very narrow space between the valve and recess, a similar space is obtained above the valve, so that the gradually contracted escape of the water is made to break the force of the shock, and provision is also made for retaining a little water above the valve, to prevent a vacuum being maintained between the valve and its seat.