INTRODUCTION

Only the sail can contend with the pump for the title of the earliest invention for the conversion of natural energy to useful work, and it is doubtful that the sail takes precedence. Because the sail cannot, in any event, be classified as a machine, the pump stands essentially unchallenged as the earliest form of machine for substituting natural energy for human physical effort.

The earliest pumps we know of are variously known, depending on which culture recorded their description, as Persian wheels, waterwheels, or norias. These devices were all undershot waterwheels containing buckets that filled with water when they were submerged in a stream and that automatically emptied into a collecting trough as they were carried to their highest point by the rotating wheel. Similar waterwheels have continued in existence in parts of the Orient even to the present day.

The best-known of the early pumps, the Archimedean screw, also persists into modern times. It is still being manufactured for low-head applications where the liquid is frequently laden with trash or other solids.

Perhaps most interesting, however, is the fact that with all the technological development that has occurred since ancient times, including the transformation from water power through other forms of energy all the way to nuclear fission, the pump remains probably the second most common machine in use, exceeded in numbers only by the electric motor.

Because pumps have existed for so long and are so widely used, it...