The Telephone An Account of the Phenomena of Electricity, Magnetism, and Sound, as Involved in Its Action   By: Amos E. Dolbear (1837-1910)

By Professor A. E. Dolbear

THE TELEPHONE

With directions for making a Speaking Telephone Illustrated 50 cents

THE ART OF PROJECTING

A Manual of Experimentation in Physics, Chemistry, and Natural History, with the Porte Lumière and Magic Lantern New Edition Revised Illustrated $2.00

MATTER, ETHER, AND MOTION

The Factors and Relations of Physical Science Illustrated $1.75

Lee and Shepard Publishers Boston

THE TELEPHONE:

AN ACCOUNT OF THE

Phenomena of Electricity, Magnetism, and Sound,

AS INVOLVED IN ITS ACTION.

WITH DIRECTIONS FOR MAKING

A SPEAKING TELEPHONE.

BY

PROF. A. E. DOLBEAR,

TUFTS COLLEGE,

AUTHOR OF "THE ART OF PROJECTING," ETC.

BOSTON: LEE & SHEPARD, PUBLISHERS.

COPYRIGHT, 1877, BY A. E. DOLBEAR.

PREFACE.

THE popular exhibitions of the speaking telephone during the past six months, together with numerous newspaper articles, have created a widespread interest in the instrument; and it has been thought that a small book explanatory of its action would meet a public want.

It has seemed to be necessary to call attention to the various phenomena and inter actions of the forces involved; and hence the author has attempted to make plain and intelligible the phenomena of electricity, magnetism, and sound. Cuts have been inserted where they could be useful in making the mechanical conditions more intelligible; and a table of tone composition has been devised, which shows at a glance the constituents of the sounds of various musical instruments.

As the speaking telephone, in which magneto electric currents were utilized for the transmission of speech and other kinds of sounds, was invented by me, I have described at some length my first instrument, and have also given explicit directions for making a speaking telephone which I know, by trial, to be as efficient as any hitherto made; but nothing in the book is to be taken as a dedication of the invention to the public, as steps have already been taken to secure letters patent according to the laws of the United States.

A. E. DOLBEAR.

COLLEGE HILL, MASS.

THE TELEPHONE.

ELECTRICITY.

SOME of the phenomena of electricity are manifested upon so large a scale as to be thrust upon the attention of everybody. Thus lightning, which accompanies so many showers in warm weather in almost every latitude, has always excited in some individuals a superstitious awe, as being an exhibition of supernatural agency; and probably every one feels more or less dread of it during a thunder shower, and this for the reason that it affects so many of the senses at the same time. The flash may be blinding to the eyes if near to us; the thunder may be deafening to the ears, and so powerful as to shake the foundations of the hills, and make the ground upon which we stand to sensibly move: these with the remembered destructive effects that have been witnessed, of buildings demolished and large trees torn to splinters in an instant, are quite sufficient to raise a feeling of dread in the strongest mind. In the polar regions, both north and south, where thunder storms are less frequent, the atmospheric electricity assumes the form called the aurora borealis, or the aurora australis, according as it is seen north or south of the equator.