A Manual of Automatic Telephony

Abstract

THE average technical student finds great difficulty in mastering the theory of the working of automatic telephony. In our opinion, this is due to the fact that nearly every book on the subject begins at once by describing in detail some complete automatic system, and the student is lost in what appears to be a hopelessly complicated maze of circuits. Mr. Wilman has appreciated a beginner's difficulties, and so begins with a few simple general considerations before describing the uses of the various devices used in practice. The diagrams given are very clear, all unnecessary details being omitted, and so the student will have little difficulty in seeing how an automatic system works. Manual systems in the past have given satisfaction, but there are several advantages in connexion with automatic systems which make them more desirable. For example, connexions can be completed more quickly and can be released instantaneously. Errors due to incorrectly hearing a number are eliminated. There is a large saving in operators' salaries. A twenty-four hours' service can be given in every exchange, and so a large number of small exchanges can economically replace a large exchange. In countries where several languages are spoken, a call may be completed with equal facility whatever language the subscriber speaks. As for many years to come automatic and manual exchanges must exist side by side, the author devotes a chapter to explaining how they can be interconnected. We recommend this book to all readers who want to get an elementary knowledge of the working of an automatic system.

A Manual of Automatic Telephony.

Charles W.

Wilman

By. (Lockwood's Manuals.) Pp. vii + 223. (London: Crosby Lockwood and Son, 1927.) 7s. 6d. net.