We have received a letter from Joseph Bailiff, Allegheny City, Pa., stating that he has been much troubled with the suction pipes; ol pumps bursting at about two of three feet below the valves—the pipes are about 27 ieei in depth. The bursting of the pipe has usoaf ly taken place in iron pumps that) have &J1I31 five feet ol water above the lower valves—tie valve being nearly 1J inches in diameter, and pipe about the same, stroke of piston S iach. es, diameter of chamber, 3 inches.1- Pumps, at Pittsburgh do not work well with m ore thai 27 feet oi suction pipe. The fault in all likelihood is in. the suction pipe—a defect in the iron. There is no lest a pressure than 15 lbs. on the square inch oi the suction pipe, and it must be well cast to stand this pressure. An air chamber should be attached behind the lower valve to every suction pipe over 12 feet in depth.