Do you know how a telephone can be induced to howl and why it should be that way in the first place? Have you ever wondered just what inventions finally extended the limits of long distance telephony to include direct communication between New York and San Francisco where previously Denver was the western boundary? Do you realize that the telephone "dial system" represents the acme in development of electrical brains? Have you heard why politeness is not the only good reason for not interrupting the speaker during a long distance conversation? These are merely a smattering of the many questions projected by the laity on the subject of electrical communication and answered by the author's series of essays.
The material is presented in such a manner that the treatment of each topic forms a sort of groundwork leading to a better understanding of the subject directly following. The author is a trained scientist and is exceedingly well versed in his subject. MoreoveL he has had considerable experience as a teacher and to reach the non-scientific reader, has followed the precepts of Mohammed in coming to the mountain. Done in this manner, the book is exceptionally free of those scientific abstractions so essential in text books. Rather, the book represents an interesting exposition on electrical communication with special care paid to the romance of its development, all of which contributes to produce a volume of effortless reading.
The author starts with the Vivisection of Speech. Here as in other instances, ether plays an important role. A description of the dial system of telephoning is aptly described as communication with Electrical Brains. Frequencies and Modulation are fundamental topics and precede a discussion of such interference phenomena as Action and Reaction, Attenuation and Echoes. Following the chapters on the characteristics of electrical communication circuits, the various forms of apparatus receive their share of attention. Transmitters and receivers now bear slight resemblance to the originals both in respect to form and performance. The vacuum tube has won the title of "Modern Jinn." There is a timely essay on the "talking pictures" and the difficulties of television are expertly balanced against the possibilities for the future. The cathode ray tube offers renewed hope.
If the reader has wondered how as many as twelve different telegraph messages can be transmitted over a single pair of wires the chapter on Filters and Channels will enlighten him considerably. Under Levels of Communication the "noisemeter" and its decibel measuring ability is discussed in relation to the part it can play in the control of sound intensities best suited to a particular type of communication. All this induces one to look eagerly forward to what the future may bring in the line of advances in electrical communication.
T. K. CLEVELAND.