CHAPTER I. INTRODUCTORY: WIRELESS TRANSMISSION AND RECEPTION. THE ETHER.

Wireless Telegraphy and Telephony Simply Explained

Transcriber's Note

This book was transcribed from scans of the original found at Google

Books. I have not transcribed the original book's index. Variant

spelling are not corrected. Some illustrations are rotated.

WIRELESS TELEGRAPHY

AND TELEPHONY

SIMPLY EXPLAINED,

A PRACTICAL TREATISE

Embracing Complete and Detailed Explanations of

the Theory and Practice of Modern Radio

Apparatus and its Present Day Applications,

together with a chapter on the

Possibilities of its Future Development

BY ALFRED P. MORGAN

EDITOR MECHANICAL AND ELECTRICAL DEPARTMENT OF THE "BOY'S MAGAZINE,"

AUTHOR OF

WIRELESS TELEGRAPH CONSTRUCTION FOR AMATEURS, ETC.

VERY FULLY ILLUSTRATED

NEW YORK

THE NORMAN W. HENLEY PUBLISHING CO.

132 NASSAU STREET

1916

COPYRIGHT 1915 AND 1912 BY

THE NORMAN W. HENLEY PUBLISHING COMPANY

Composition, Electrotyping and Printing

By J. J. LITTLE & Ives Co., New York

PREFACE

Probably no marvel of modern science so grips the imagination as the

mystery of those quivering impulses which go forth invisibly to link a

ship sailing over the seas with the shores of the distant land.

The author has endeavored to furnish a comprehensive explanation, in

simple language, of the theory and practice of this wonderful art, and

to explain, as far as possible, the importance of the position occupied

by wireless telegraphy to-day and the possibilities of to-morrow.

The title of this book naturally limits the amount of discussion that

can be undertaken, and so, in the space at command, there has not been

any real attempt made to enter into any engineering or constructive

details further than is necessary to make the text clear.

Much that might properly be made a part of the preface has been embodied

in the book, in order to avoid repetition, and to also bring certain

matter to the attention of those readers who consider a preface to be

merely an opportunity for the author of a book to express opinions very

often quite foreign to the title, and so unconcernedly skip it with

hardly more than a passing glance.

The author wishes to extend his sincere thanks to Mr. H. W. Young,

Editor of Popular Electricity; to Mr. John Firth, to Colonel George P.

Scriven, and to the Scientific American, for their kindness in supplying

photographs for some of the illustrations, and to his friend, Mr.

Safford Adams, who has kindly read the proofs and made many valuable

suggestions.

ALFRED P. MORGAN. May, 1915.

TO

NIKOLA TESLA

WHOSE GENIUS HAS HARNESSED ELECTRICITY TO THE DAILY WORK OF MAN AND

WHOSE INVENTIONS ARE THE BASIS OF ALL MODERN WIRELESS TRANSMISSION, THIS

BOOK IS DEDICATED.

TABLE OF CONTENTS

PREFACE

CHAPTER I. INTRODUCTORY: WIRELESS TRANSMISSION AND RECEPTION. THE

ETHER. ELECTRICAL OSCILLATIONS. ELECTROMAGNETIC WAVES.

CHAPTER II. THE MEANS FOR RADIATING AND INTERCEPTING ELECTRIC WAVES.

AERIAL SYSTEMS. EARTH CONNECTION.

CHAPTER III. THE TRANSMITTING APPARATUS.

CHAPTER IV. THE RECEIVING APPARATUS.

CHAPTER V. TUNING AND COUPLING, DIRECTIVE WAVE TELEGRAPHY.

CHAPTER VI. THE DIGNITY OF WIRELESS. ITS APPLICATIONS AND SERVICE.

WIRELESS IN THE ARMY AND NAVY. WIRELESS ON AN AEROPLANE. HOW A

MESSAGE IS SENT AND RECEIVED.

CHAPTER VII. THE EAR. HOW WE HEAR. SOUND AND SOUND WAVES. THE VOCAL

CHORDS. THE STRUCTURE OF SPEECH.

CHAPTER VIII. THE TELEPHONE TRANSMITTER AND RECEIVER. THE PHOTO

PHONE. THE THERMOPHONE. THE SELENIUM CELL. THE SPEAKING ARC.

CHAPTER IX. THE WIRELESS TELEPHONE.

CHAPTER X. REMARKS. THEORY. ACCOMPLISHMENTS. MAXWELL'S HERTZ'S

DISCOVERY. THE FUTURE.

CATALOGUE OF GOOD, PRACTICAL BOOKS

LIST OF ILLUSTRATIONS

Fig. 1.—Throw a stone into a pool of water and little waves will radiate

from the spot where the stone struck.

Fig. 2.—A Leyden jar is a glass jar lined inside and outside with

tinfoil for about two-thirds of its height.

Fig. 3.—A static machine, connected to a Leyden jar.

Fig. 4.—A Leyden jar discharging through a coil of wire.

Fig. 5.—Curved line representing an oscillatory discharge of a Leyden

jar.

Fig. 6.—Navy type of Leyden jars.

Fig. 7.—The simplest practical transmitter.

Fig. 8.—A cross-section of the aerial and atmosphere.

Fig. 9.—Under the same conditions, but viewed from above.

Fig. 10.—A simple receiving arrangement.

Fig. 11.—An amateur aerial and station.

Fig. 12.—The Army wireless station at Fort Gibbons.

Fig. 13.—Lightning discharge near Montclair, N. J.

Fig. 14.–Photo of double lightning discharge passing to earth near the

First Orange Mountain, Montclair, N. J.

Fig. 15.—Vertical aerials of the grid, fan and inverted pyramid types.

Fig. 16.—A diagram showing pyramid aerial.

Fig. 17.–A diagram illustrating the directive action of a flat-top

aerial.

Fig. 18.—Aerials of the "V" and inverted "L" types.

Fig. 19.—A diagram showing the arrangement of a "T" aerial.

Fig. 20.—Flat top aerials of the inverted "U" and "T" types.

Fig. 21.—Umbrella aerial.

Fig. 22.—An amateur aerial (flat top).

Fig. 23.—Diagram showing the difference between loop and straightaway

aerials.

Fig. 24.—Showing how wires are arranged and insulated.

Fig. 25.—Aerial insulator.

Fig. 26.—Leading-in insulator.

Fig. 27.–A side view of the aerial shown in Fig. 22.

Fig. 28.—Diagram showing how batteries may be arranged.

Fig. 29.—The power plant of a Marconi transatlantic station.

Fig. 30.—If a magnet be suddenly plunged into a hollow coil of wire a

momentary current will be induced in the coil.

Fig. 31.—Magnetic phantom formed by a bar magnet.

Fig. 32.—Magnetic phantom formed by a wire carrying current.

Fig. 33.—Magnetic phantom formed by a coil of wire carrying current.

Fig. 34.—Diagram of induction coil.

Fig. 35.—Induction coil for wireless telegraph purposes.

Fig. 36.—Induction coil primary and secondary.

Fig. 37.—Interrupter for induction coil.

Fig. 38.—Electrolytic interrupter.

Fig. 39.—Open and closed core transformers.

Fig. 40.—Lines representing direct and intermittent direct currents.

Fig. 41.—Diagram representing alternating current.

Fig. 42.—High potential humming transformer.

Fig. 43.—High potential closed core transformer for wireless work.

Fig. 44.—Leyden jar set for oil immersion.

Fig. 45.—Oil immersed condenser.

Fig. 46.—Diagram showing construction of condenser.

Fig. 47.–Tubular condenser.

Fig. 48.—Helix.

Fig. 49.—Close coupled helix.

Fig. 50.—Spark gap.

Fig. 51.—Circuit showing tuned transmitting system employing close

coupled helix.

Fig. 52.—Photo of spark gap.

Fig. 53.—Quenched spark gap.

Fig. 54.—Diagram of aerial switch.

Fig. 55.—Photo of aerial switch.

Fig. 56.—Anchor gap.

Fig. 57.–Wireless key.

Fig. 58.—Photo of wireless key.

Fig. 59.—Key and aerial switch.

Fig. 60.—Portable receiving set and case.

Fig. 61.—Complete receiving outfit.

Fig. 62.—Portable pack set.

Fig. 63.—Complete receiving set.

Fig. 64.—Showing the construction of a watch case telephone receiver.

Fig. 65.—Pickard adjustable telephone receivers.

Fig. 66.—Illustrating the valve action of a rectifying detector.

Fig. 67.—A new type of silicon detector.

Fig. 68.—Diagram drawing analogy between rectifying action of a detector

and pump.

Fig. 69.—Pyron detector.

Fig. 70.—Perikon detector.

Fig. 71.—Silicon detector.

Fig. 72.—Electrolytic detector.

Fig. 73.—Electrolytic detector in circuit.

Fig. 74.—Potentiometer.

Fig. 75.—Diagram showing how potentiometer is connected in a circuit.

Fig. 76.—Analogy between swinging and tuning.

Fig. 77.—Receiving a message in a Marconi transatlantic station.

Fig. 78.—Tuning coil of the double slide type.

Fig. 79.—Diagram showing fixed condenser in circuit.

Fig. 80.–Fixed condenser.

Fig. 81.—Rotary variable condenser.

Fig. 82.—Interior of rotary variable condenser, showing construction.

Fig. 83.—Dr. Seibt's rotary variable condenser.

Fig. 84.—Sliding plate variable condenser.

Fig. 85.—Diagram showing arrangement of rotary variable condenser in

receiving circuit.

Fig. 86.—Chain and ball arranged to illustrate the effect of tuning.

Fig. 87.—Loose coupled helix.

Fig. 88.—Hot-wire ammeter.

Fig. 89.—The principle of the hot-wire ammeter.

Fig. 90.—Diagram showing loose coupled helix in circuit.

Fig. 91.—Loose coupled tuning coil.

Fig. 92.—Loose coupled tuner.

Fig. 93.—Diagram showing position of loose coupler in circuit.

Fig. 94.–Fort Gibbons, Alaska, wireless station.

Fig. 95.—Transmitting condenser.

Fig. 96.—Braun's method for directing wireless telegraph signals.

Fig. 97.—Bellini-Tosi radio-goniometer.

Fig. 98.—Arrangement of Bellini and Tosi for directive wireless

telegraphy.

Fig. 99.—Complete receiving and transmitting outfit.

Fig. 100.—Special lightweight wireless telegraph set for airship

service.

Fig. 101.—Telefunken wireless cart, showing transmitter.

Fig. 102.—Telefunken wireless cart for military service.

Fig. 103.—Telefunken wireless wagon set in operation at Fort Leavenworth.

Fig. 104.—Wireless room aboard the U. S. transport "Buford".

Fig. 105. The apparatus set up for operation.

Fig. 106.—Wireless equipped automobile.

Fig. 107.—Co. Signal Corps at San Antonio.

Fig. 108.—U. S. Signal Corps pack set shown open and closed.

Fig. 109.—The receiving apparatus of the airship "America".

Fig. 110.—Interior of the N. Y. Herald Press station.

Fig. 111.—Operating the U. S. Signal Corps airship wireless apparatus.

Fig. 112.—The N. Y. Herald station, showing aerial.

Fig. 113.—Operator Jack Irwin overhauling the wireless apparatus for the

dirigible balloon "America".

Fig. 114.—Morse code.

Fig. 115.—Continental code.

Fig. 116.—Transmitting equipment of the high-power station at Nauen.

Fig. 117.—Duplex receiving apparatus.

Fig. 118.—Breaking-in system.

Fig. 119.—The receiving apparatus of the station at Nauen.

Fig. 120.—Diagram of the ear.

Fig. 121.—The ossicles.

Fig. 122.—Bon jour.

Fig. 123.—Experiment showing sounding bodies are in vibration.

Fig. 124.—Method of registering vibrations of a tuning fork.

Fig. 125.—Way line made by a bristle attached to a tuning fork prong in

vibration when passed over smoked glass.

Fig. 126.—Illustrating the action of air waves.

Fig. 127.—The vocal chords in position for making a sound.

Fig. 128.—The vocal chords when relaxed.

Fig. 129.–Koenig's manometric flame apparatus.

Fig. 130.—Appearance of manometric flame in revolving mirror.

Fig. 131.—Diagram of a telephone transmitter.

Fig. 132.—Diagram showing the principle and construction of the

telephone receiver.

Fig. 133.—The photophone.

Fig. 134.—Photophone receiving apparatus.

Fig. 135.—Photophone transmitting apparatus.

Fig. 136.—Powerful searchlight arranged to transmit speech over a beam

of light.

Fig. 137.—The electric arc.

Fig. 138.—Circuit showing how a singing arc is arranged.

Fig. 139.—A logical form of wireless telephone which is impractical.

Fig. 140.—DeForest wireless telephone equipment.

Fig. 141.—Wireless telephone receiving apparatus (induction method).

Fig. 142.—Fessenden wireless telephone transmitting phonograph music.

Fig. 143.—Diagram illustrating why damped oscillations will not carry

the voice.

Fig. 144.—How the sound waves of the voice are impressed upon undamped

oscillations.

Fig. 145.—Arrangement of the speaking arc.

Fig. 146.—Diagram showing how a wireless telephone transmitting system

is arranged.

Fig. 147.—Poulsen wireless telephone equipment.

Fig. 148.—The Majorana wireless telephone transmitter.

Fig. 149.—Showing the brush discharge from a Marconi transatlantic

aerial at night.

Fig. 150.—An amateur wireless' telegraph station.

Fig. 151.—The high-power naval wireless telegraph station under

construction at Washington, D. C.

Fig. 152.—The curved lines represent the radius of the government

high-power wireless stations and show the zones over which direct

communication may be had with ships.

Fig. 153.—The aerial system of a transatlantic station.

Fig. 154.—Fong Yee, a Chinese amateur wireless operator.

Fig. 155.—Tesla world power plant.

Fig. 156.—Twenty-five-foot sparks from a Tesla transformer.

CHAPTER I. INTRODUCTORY: WIRELESS TRANSMISSION AND RECEPTION. THE ETHER.

ELECTRICAL OSCILLATIONS. ELECTROMAGNETIC WAVES.

Wireless telegraphy, that marvelous art which has made possible the

instantaneous transmission of intelligence between widely distant parts

having no apparent physical connection save that of the earth, air, and

water, is one of those wonders of science which appeal to the average

mind as either incomprehensible or only explainable through the use of

highly technical language. Contrary to this general opinion, however,

the whole theory and practice of the wireless transmission of messages

is capable of the simplest explanation.

[Illustration: FIG. 1.—Throw a stone into a pool of water and little

waves will radiate from the spot where the stone struck.]

Throw a stone into a pool of water. A disturbance is immediately

created, and little waves will radiate from the spot where the stone

struck the water, gradually spreading out into enlarging circles until

they reach the shores or die away. By throwing several stones in

succession with varying intervals between them it would be possible to

so arrange a set of signals that they would convey a meaning to one who

is initiated, standing on the opposite side of the pool. The little

waves are the vehicle which transmits the intelligence, and the water

the medium in which the waves travel.

Wireless telegraph instruments are simply a means for creating and

detecting waves in a great pool of ether.

Scientists suppose that all space and matter is pervaded with a

hypothetical medium of extreme tenuity and elasticity, called

luminiferous ether, or simply ether.

Although ether is invisible, odorless, and practically weightless, it is

not merely the fantastic creation of speculative philosophers, but is as

essential to our existence as the air we breathe and the food we eat. By

imagining and accepting its reality, it is possible to explain and

understand many scientific puzzles. The universe is a vast pool of

ether. It is all-pervading. There is no void. It is diffused even among

the molecules of which solid bodies are composed. The study of this

substance is, perhaps, one of the most fascinating and important duties

of the physicist.

Ninety million miles away from our earth is a huge flaming body of

vapors and gases, called the sun. This seething mass of flame and heat

furnishes us more than mere winter and summer and night and day, for we

on this earth are not living on our own resources, and the real work of

the world so necessary for even bare existence is accomplished by the

energy of the sun stored up in coal, in plants and trees and mountain

torrents.

Light is known to be vibrations of an extremely rapid

period—*electromagnetic waves*, they are called. Heat can be shown to be

of the same nature. Traveling at the rate of over 180,000 miles per

second, these two great gifts of the sun come streaming continually down

to us over the inconceivable distance of almost 100,000,000 miles. Both

require a medium for their propagation. The ether supplies it. It is the

substance with which the universe is filled. Incidentally it is also the

seat of all electrical and magnetic forces.

[Illustration: FIG. 2.—A Leyden jar is a glass jar lined inside and out

with tinfoil for about two-thirds of its height.]

In throwing the stone into the pool of water, muscular energy of the arm

is transferred to the stone, and the latter, upon striking the surface

of the pond, imparts a portion of that stored energy to the little waves

which are immediately created in the water. In setting up

electromagnetic waves for wireless communication the energy imparted to

the ether is electrical energy, developed by certain interesting

instruments explained further on.

Let us consider briefly how the waves are created in a wireless

telegraph station. Almost every one has seen and heard the brilliant

snapping spark produced by the discharge of a Leyden jar. A Leyden jar

in its common form is a glass jar lined inside and out with tinfoil for

about two thirds of its height. A brass rod, terminating in a knob,

connects below with the inner coating, usually by means of a loose

chain. It may be described as a device which is capable of storing

electricity in the form of energy and discharging this energy again in

actual electricity.

This discharge has been the subject of many interesting investigations

of direct interest.

[Illustration: FIG. 3.—A static machine connected to a Leyden jar.]

The inner and outer coatings are connected to the terminals of a static

electric machine (an apparatus for generating electricity), and the

machine set in rotation. After the jar has been charged, the electric

machine is disconnected and one end of a coil of heavy wire connected to

the outside coating, while the other end of the wire is made to approach

the knob connected with the inner coating. Before the end of the wire

reaches the knob a discharge occurs through the coil, producing a noisy

brilliant spark between the wire and the knob. The discharge appears

like a single spark, but in reality it is composed of a great many

following each other in rapid succession. The jar discharges its energy,

first by a tremendous rush of current in one direction, and then another

discharge somewhat smaller than the first in the opposite direction.

There is a series of these discharges in reverse directions, but each

discharge is less and less, until the whole amount of energy is

expended. The complete series of discharges takes place in an almost

immeasurable fraction of time. It is from this phenomenon that the

electrical term "high frequency oscillations," so often heard of in

"wireless" parlance, is derived.

[Illustration: FIG. 4.—A Leyden jar discharging through a coil of wire

produces a brilliant spark and high frequency oscillations are created.]

[Illustration: FIG. 5.—Curved line representing an oscillatory discharge

of a Leyden jar.]

[Illustration: FIG. 6.—Navy type of Leyden jars. Coated with copper

deposited upon the surface of the glass.]

High frequency oscillations are the "pebbles" which, dropped into the

vast pool of ether, everywhere, set up "ripples" called electromagnetic

waves (identical with the electromagnetic waves of light, but longer and

so beyond the limits of our spectrum and the vision of the eye). The

manner in which this is accomplished may be explained by saying that the

charge creates a state of strain in the surrounding ether, and then

abruptly releases it. Ether possesses a high degree of elasticity, so

that when the state of strain is thus suddenly released, it immediately

returns to its former state. The sudden motion of the ether results in

waves which spread out from their source in enlarging circles.

Wireless telegraphy, as it is practiced to-day, is based upon the fact

that a system of wires or circuits, through which high frequency

oscillations are surging, becomes a source of electromagnetic waves.

Various methods have been devised for making the system more efficient

and capable of giving better results with a given amount of power.

[Illustration: FIG. 7.—The simplest practical transmitter that it is

possible to devise for the purpose of sending messages.]

Fig. 7 is a diagram showing the simplest practical transmitter that it

is possible to devise for the purpose of sending messages a sufficient

distance to be of any value.

It would be impractical to use a static electric machine for wireless

transmission, and so an induction coil or transformer is employed. These

latter instruments are for the purpose of raising electric currents of a

comparatively low voltage to the high potential, where they have the

power of generating high frequency oscillations.

In the illustration the current from a battery is led into the primary

of an induction coil. The primary is simply a coil consisting of a few

turns of wire, which induces a high voltage in a second coil consisting

of a larger number of turns, and called the secondary. The terminals of

the secondary are led to a spark gap—an arrangement composed of two

polished brass balls, separated by a small air space. One of the balls,

in turn, is connected to a metal plate buried in the earth, and the

other to a network of wires suspended high in the air and insulated from

all surrounding objects.

As noted above, a Leyden jar consists of two metallic coatings,

separated by a wall of glass. The purpose of the coatings is to form a

conductor and carry an electric charge. A Leyden jar possesses a

characteristic called, in electricity, capacity. Any two conductors

separated by an insulating medium possess "capacity" and all the

properties of a Leyden jar or condenser.

The waves generated by a Leyden jar would be somewhat weak and confined

to its own immediate neighborhood, so recourse is had to the aerial and

ground, in order to increase the area over which the oscillations exert

their influence in setting up the electric waves. The aerial system

corresponds to one coating of the Leyden jar, and the ground to the

other. The insulating medium in between, corresponding to the glass, or

dielectric, is the atmosphere.

When the key connected to the induction coil is pressed, the battery

current flows through the primary and induces a high voltage current in

the secondary, which charges the aerial and ground exactly as the static

machine charges the two coatings of the Leyden jar. A spark then leaps

across the spark gap and the current surges back and forth through the

aerial, generating "high frequency oscillations" which, in turn, set up

a state of strain in the surrounding ether, and cause the waves to

travel out from the system.

[Illustration: FIG. 8. If a cross section of the aerial and atmosphere

could be made in the same manner that an apple is sliced with a knife

and the waves held stationary, they would appear as above.]

These waves follow the contour of the earth, and so may cross mountains

and valleys, and travel anywhere. They radiate from the aerial like the

ripples from a pebble in a pool of water, in gradually enlarging

circles. If a cross section of the aerial and atmosphere could be made

in the same manner that an apple can be sliced with a knife, and the

waves held stationary long enough to see them, they would appear as in

Fig. 8. The curved lines represent the lines of strain induced by the

oscillations. Each group of lines represents a wave. It will be noticed

as they radiate farther from the aerial that they become larger and

spread out.

[Illustration: FIG. 9.—Under the same conditions, but when viewed from

above, the appearance would be that of a series of concentric circles.]

The electromagnetic waves have the power of exciting oscillations in a

conductor on which they impinge. This is made use of for the purpose of

receiving the messages. When the waves strike the aerial of a distant

station they set up high frequency oscillations, which are usually too

weak to make their presence known except with the aid of a sensitive

device, called a detector.

[Illustration: FIG. 10.—A simple receiving arrangement. The detector

rectifies the oscillatory currents passing from the aerial to the

ground so that they will flow through the telephone receiver and

register as sound.]

The most prominent type of detector in use to-day is a crystal of

silicon, iron pyrites, zincite or certain other minerals. The mineral is

placed between two contact points, one or both of which are adjustable

so that the most sensitive portion of the mineral may be selected. A

telephone receiver is connected across the terminals of the detector.

When the electromagnetic waves from the transmitting station strike the

aerial of the receiving station, they set up therein a series of high

frequency oscillations, corresponding to the Morse signals emitted from

the transmitter. The oscillations flow back and forth through the aerial

and ground, striking the mineral detector on their journey. The high

frequency oscillations are alternating currents, because they reverse

their direction many thousand times per second. Such a current will not

pass through the telephone receiver, because the little magnets

contained therein exert a choking action on alternating currents of high

frequency and effectually block their passage. The mineral detector acts

as a valve, allowing the current to pass through in one direction, but

not permitting it to return or go in the opposite direction. The result

is a series of impulses flowing in one direction only, and therefore

called a direct current. Such a current will flow through a telephone

receiver and produce a motion of the diaphragm which imparts its motion

to the surrounding air, the result being sound waves audible to the ear.

By varying the periods during which the key is pressed and the

oscillations are being produced, according to a prearranged code, the

sounds in the receiver may be made to assume an intelligible meaning.