DURING recent years there has been an increasing demand for machines and devices which will convert alternating currents into direct currents. Bulk supplies are usually given by alternating currents, but for some supply networks and for traction, direct currents are required. In these circumstances, devices such as machines called rotary converters, or stationary apparatus utilizing a physical property of electrolytes?electric arcs, gas discharge tubes, etc.?are employed. The latter kinds of apparatus are called rectifiers and are of many types utilizing very different physical phenomena.
Mercury Arc Rectifier Practice
By F. C. Orchard. Pp. xi + 224 + 23 plates. (London: Chapman and Hall, Ltd., 1935.) 15s. net.