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

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

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Fig. 5.-Curved line representing an oscillatory discharge

of a Leyden jar

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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

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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 pyra-

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Fig. 17. A diagram illustrating the directive action of a flattop aerial

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

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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

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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 cur-

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 cur

rents

Fig. 43.-High potential closed core transformer for wireless

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Fig. 47.-Tubular condenser

Fig. 48.-Helix

Fig. 49.-Close coupled helix

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Fig. 41.-Diagram representing alternating current

Fig. 42. High potential humming transformer

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Fig. 44.-Leyden jar set for oil immersion

Fig. 45.-Oil immersed condenser

Fig. 46.-Diagram showing construction of condenser

Fig. 50.-Spark gap

Fig. 51.-Circuit showing tuned transmitting system employ

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

Fig. 65. Pickard adjustable telephone receivers

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Fig. 66.-Illustrating the valve action of a rectifying detector
Fig. 67.-A new type of silicon detector .

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Fig. 68.-Diagram drawing analogy between rectifying action of a detector and pump

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

Fig. 79.-Diagram showing fixed condenser in circuit

Fig. 76.—Analogy between swinging and tuning

Fig. 77. Receiving a message in a Marconi transatlantic

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

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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

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Fig. 85.-Diagram showing arrangement of rotary variable condenser in receiving circuit

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

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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

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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 air-
ship 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. D 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

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Fig. 117.-Duplex receiving apparatus

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Fig. 118-Breaking-in system.

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Fig. 119. The receiving apparatus of the station at Nauen
Fig. 120.-Diagram of the ear

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

tion

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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

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Fig. 129.—Koenig's manometric flame apparatus

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Fig. 130.-Appearance of manometric flame in revolving

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Fig. 131.-Diagram of a telephone transmitter

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

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Fig. 133. The photophone

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Fig. 134.-Photophone receiving apparatus

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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.

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

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

Fig. 143.-Diagram illustrating why damped oscillations will not carry the voice

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

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Fig. 145.-Arrangement of the speaking arc

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Fig. 146.-Diagram showing how a wireless telephone transmitting system is arranged.

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Fig. 147.-Poulsen wireless telephone equipment

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Fig. 148.—The Majorana wireless telephone transmitter

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Fig. 149. Showing the brush discharge from a Marconi transatlantic aerial at night

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Fig. 150.-An amateur wireless telegraph station

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Fig. 151.-The high-power naval wireless telegraph station under construction at Washington, D. C.

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