Zim and Skelly discuss informally the uses, manufacture and operation of plumbing systems, and their tendency to skim lightly over some puzzling matters (how does ""the energy of the sun. . . raise water to high places"" and what exactly happened when ""the original lift pump. . . sucked air from a pipe""?) is balanced by the appeal of Ames & Erikson's precise diagrams of valves, fittings, meters and pipe systems. And those charts which distinguish a 45 degree street elbow from a reducing T and photos like that of a 20 foot high gate valve have a concrete fascination that will extend beyond the clear but generalized elementary level text.