Latest / History of the Universe Physics & Electricity Vol. 3 / 026 - Electricity - Chapter 8 - The Telephone Part 1

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026 - Electricity - Chapter 8 - The Telephone Part 1 · History of the Universe Physics & Electricity Vol. 3

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  Speaker 1: Section twenty six The Science History of the Universe, Volume three.
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  Speaker 1: This is a LibriVox recording. All LibriVox recordings are in
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  Speaker 1: the public domain. For more information or to volunteer, please
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  Speaker 1: visit LibriVox dot org. The Science History of the Universe,
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  Speaker 1: Volume three, edited by Francis Rolt Wheeler. Electricity, Chapter eight,
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  Speaker 1: the telephone, Part one. In eighteen fifty four, a Frenchman,
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  Speaker 1: Charles Bursull predicted the transmission of speech and outlined a
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  Speaker 1: method correct save in one particular, but for which error
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  Speaker 1: one following his directions could have produced a speaking telephone.
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  Speaker 1: His words at this date seem almost prophetic. I have
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  Speaker 1: asked myself, for example, if the spoken word itself could
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  Speaker 1: not be transmitted by electricity. In a word, if what
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  Speaker 1: was spoken in Vienna may not be heard in Paris,
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  Speaker 1: the thing is practical in this way. Suppose that a
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  Speaker 1: man speaks near a movable disc sufficiently flexible to lose
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  Speaker 1: none of the vibrations of the voice. That this disc
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  Speaker 1: alternately makes and breaks the connection from a battery. You
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  Speaker 1: may have at a distance another disc which will simultaneously
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  Speaker 1: execute the same vibrations the words makes and breaks. In
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  Speaker 1: Borsoul's quotation, have been italicized by the present writer. They
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  Speaker 1: formed the keynote of the failures of those who subsequently
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  Speaker 1: followed Borsoul's directions literally. Philip Reese, a German inventor, constructed
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  Speaker 1: what he called a telephone in eighteen sixty one, following
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  Speaker 1: implicitly the path outlined by Bursul. He mounted a flexible
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  Speaker 1: diaphragm over an opening in a wooden box, and on
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  Speaker 1: the center of the diaphragm fastened a small piece of platinum.
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  Speaker 1: Near this he mounted a heavy brass spring with which
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  Speaker 1: the platinum alternately made and broke contact when the diaphragm
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  Speaker 1: was caused to vibrate. These contact points formed the terminals
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  Speaker 1: of a circuit containing a battery and the receiving instrument.
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  Speaker 1: His receiver assumed various forms, prominent among which was a
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  Speaker 1: knitting needle wrapped with silk insulated copper wire and mounted
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  Speaker 1: on a cigar box for a sounding board. Its operation
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  Speaker 1: was as follows. The sound waves set up in the
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  Speaker 1: air struck against the diaphragm of the transmitter, causing it
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  Speaker 1: to vibrate in unison with them. This caused the alternate
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  Speaker 1: making and breaking of the circuit at the point of
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  Speaker 1: contact between the platinum and the spring, and allowed intermittent
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  Speaker 1: currents to flow through the receiver. These caused a series
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  Speaker 1: of sounds in the kneading needle. By virtue of Page's effect,
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  Speaker 1: the sounding board vibrated in unison with the molecular vibrations
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  Speaker 1: of the needle, and the sound was thus greatly amplified.
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  Speaker 1: Reese's telephone could be depended upon to transmit only musical sounds.
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  Speaker 1: The question as to whether it actually did transmit speech
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  Speaker 1: has been the subject of much discussion. But if it
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  Speaker 1: did this at all, it was very imperfectly. The cause
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  Speaker 1: of its failure, says K. B. Miller in his American
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  Speaker 1: Telephone Practice. To successfully transmit speech will be understood from
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  Speaker 1: the following facts. A simple musical tone is caused by
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  Speaker 1: vibrations of very simple forms, while sound waves produced by
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  Speaker 1: the voice in speaking are very complex and their nature.
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  Speaker 1: Sound possesses three qualities, pitch depending entirely on the frequency
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  Speaker 1: of the vibrations, loudness depending on the amplitude of the vibrations,
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  Speaker 1: and tambre or quality depending on the form of the vibration.
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  Speaker 1: The tones of a flute and a violin may be
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  Speaker 1: the same as to pitch and loudness, yet be radically different.
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  Speaker 1: This difference is in tambre or quality. Reese's transmitter, as
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  Speaker 1: he adjusted, it was able only to make and break
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  Speaker 1: the circuit, and a movement of the diaphragm barely sufficient
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  Speaker 1: to break the circuit produced the same effect as a
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  Speaker 1: much greater movement. The current therefore flowed with full strength
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  Speaker 1: until the circuit was broken. When it stopped entirely, the
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  Speaker 1: intermediate strengths needed for reproducing the delicate modulations of the
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  Speaker 1: voice were entirely lacking. This apparatus could therefore exactly reproduce
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  Speaker 1: the pitch of a sound, but not its timbre and
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  Speaker 1: relative loudness. For the next fifteen years, no apparent advance
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  Speaker 1: was made in the art of telephony, although several inventors
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  Speaker 1: gave it their attention. In eighteen seventy six, Professor Alexander
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  Speaker 1: Graham Bell and Professor Elisha Gray almost simultaneously invented successful
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  Speaker 1: speaking telephones. Gray has been one of the principal claimants
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  Speaker 1: for the honor of being the first inventor of the telephone,
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  Speaker 1: but Bell has apparently established his right to it, and
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  Speaker 1: has also reaped the prophet for after long litigation. The
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  Speaker 1: United States Patent Office and the courts have awarded the
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  Speaker 1: priority to him, as against Gray and many others. Bell
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  Speaker 1: possessed a greater knowledge of acoustics than of electrical science,
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  Speaker 1: and it was probably this that led him to appreciate
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  Speaker 1: wherein others had failed. His instrument consisted of a permanent
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  Speaker 1: bar magnet, having on one end a coil of fine wire.
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  Speaker 1: In front of the pole carrying the coil, a thin
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  Speaker 1: diaphragm of soft iron was so mounted as to allow
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  Speaker 1: its free vibration close to the pole. Two points will
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  Speaker 1: be noticed, says Miller in the work before sighted, which
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  Speaker 1: have heretofore been absent, That no battery is used in
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  Speaker 1: the circuit, and that the transmitting and receiving instruments are
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  Speaker 1: exactly alike. When the soft iron diaphragm of the transmitting
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  Speaker 1: instrument is spoken to, it vibrates in exact accordance with
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  Speaker 1: the sound waves striking against it. The movement of the
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  Speaker 1: diaphragm causes changes in the magnetic field in which lies
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  Speaker 1: the coil, which changes has already pointed out, cause currents
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  Speaker 1: to flow in the circuit. These currents flow first in
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  Speaker 1: one direction, and then in the other varying in unison
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  Speaker 1: with movements of the diaphragm, the waves being very complex
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  Speaker 1: as represented graphically passing along the line wire. These electrical
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  Speaker 1: impulses so feeble that only the most delicate instruments can
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  Speaker 1: detect them. Alternately increase and decrease the strength of the
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  Speaker 1: permanent magnet of the receiving instrument, and thereby cause it
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  Speaker 1: to exert a varying pull on its soft iron diaphragm,
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  Speaker 1: which as result takes up the vibrations and reproduces the
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  Speaker 1: sound faithfully. Bell's earlier instruments were exhibited in eighteen seventy
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  Speaker 1: six at the Centennial in Philadelphia. The receiver consisted of
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  Speaker 1: a tubular magnet composed of a coil of wire surrounding
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  Speaker 1: a core and enclosed in an iron tube which was
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  Speaker 1: about quarter inches in diameter and three inches long. This
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  Speaker 1: tube was closed by a thin iron armature or diaphragm,
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  Speaker 1: which rested loosely on the upper face of the iron tube,
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  Speaker 1: the length of the core being such as not quite
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  Speaker 1: to touch the diaphragm when in this position. The whole
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  Speaker 1: of it was mounted on a base, arrangements being made
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  Speaker 1: to adjust the air gap between the pole of the
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  Speaker 1: core and the diaphragm by means of a thumbscrew. The
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  Speaker 1: transmitter consisted of an electro magnet in front of the core,
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  Speaker 1: on which was adjustably mounted, a diaphragm of gold beater's
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  Speaker 1: skin carrying a small iron armature at its center. A
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  Speaker 1: long mouthpiece into which the sounds to be transmitted were spoken,
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  Speaker 1: served to convey the sound waves more directly to the diaphragm.
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  Speaker 1: Nearly all books and articles on telephones, says Miller, that
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  Speaker 1: treat of Bell's earlier receiver at all show and describe
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  Speaker 1: it as having the diaphragm fastened at one edge by
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  Speaker 1: a single small screw to the upper face of the
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  Speaker 1: iron tube, and sprung away from the tube at its
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  Speaker 1: opposite side. This mistake occurred in the first two editions
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  Speaker 1: of this work, and would have been in this one
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  Speaker 1: but for Thomas D. Lockwood, who was kind enough to
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  Speaker 1: call attention to it. The origin of the error is
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  Speaker 1: explained in the following interesting extract from a letter written
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  Speaker 1: by mister Lockwood to the writer of this book. This
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  Speaker 1: mistake first appeared in the account given by Engineering of
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  Speaker 1: Sir William Thompson's address to the British Association in September
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  Speaker 1: eighteen seventy six, and has been universally copied. The origin
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  Speaker 1: of the mistake is very odd. The screw of the instrument,
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  Speaker 1: given to Sir William Thompson, and which he exhibited in
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  Speaker 1: England on his return, was put through a hole in
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  Speaker 1: the edge of the diaphragm and engaged with the threaded
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  Speaker 1: whole of the tube for the purpose of attaching the
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  Speaker 1: diaphragm while in transit to prevent it from getting lost.
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  Speaker 1: No one, however, notified Sir William of this, it probably
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  Speaker 1: having been forgotten, and Sir William seems to have forgotten
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  Speaker 1: what the instrument as he saw in Philadelphia looked like. Finally,
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  Speaker 1: in knocking about among Sir William's luggage, the free end
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  Speaker 1: of the diaphragm was apparently, and without doubt unintentionally bent upward,
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  Speaker 1: as the picture shows. But when so bent, being at
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  Speaker 1: the same time rigidly fastened at the opposite edge, it
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  Speaker 1: would not and could not work, And when Sir William
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  Speaker 1: showed it in England, he couldn't make it work. Bell's instrument,
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  Speaker 1: in a modified form, is the standard of today. It
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  Speaker 1: is now used as a receiver, only a more efficient transmitter,
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  Speaker 1: depending upon entirely different principles having been invented. In speaking
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  Speaker 1: of Bell's invention, Sir William Thompson, Lord Kelvin, said, who
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  Speaker 1: can but admire the hardihood of invention which devised such
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  Speaker 1: very slight means to realize the mathematical conception that, if
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  Speaker 1: electricity is to convey all the delicacies of quality which
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  Speaker 1: distinguish articulate speech, the strength of its current must vary
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  Speaker 1: continuously as nearly as may be in simple proportion to
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  Speaker 1: the velocity of a particle of air engaged in constituting
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  Speaker 1: the sound. Much has been said and books have been
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  Speaker 1: written on the rights of Reee as the inventor of
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  Speaker 1: the speaking telephone. The validity of Bell's controlling patent was
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  Speaker 1: the subject of many attacks, the litigation finally reaching the
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  Speaker 1: Supreme Court of the United States. In the opinion of
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  Speaker 1: this Court October Term eighteen eighty seven, the following brief
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  Speaker 1: but comprehensive statement is found. We have not had our
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  Speaker 1: attention called to a single item of evidence which hens
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  Speaker 1: in any way to show that Reese or anyone who
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  Speaker 1: wrote about him, had in his mind that anything else
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  Speaker 1: than the intermittent current caused by the opening and closing
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  Speaker 1: of the circuit could be used to do what was wanted.
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  Speaker 1: No one seems to have thought that there could be
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  Speaker 1: another way. All recognized the fact that the minor differences
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  Speaker 1: in the original vibrations had not been satisfactorily reproduced, but
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  Speaker 1: they attributed it to the imperfect mechanism of the apparatus used,
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  Speaker 1: rather than to any fault in the principle on which
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  Speaker 1: the operation was to depend. It was left for Bell
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  Speaker 1: to discover that the failure was due not to workmanship,
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  Speaker 1: but to the principle which was adopted as the basis
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  Speaker 1: of what had to be done. He found that what
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  Speaker 1: he called the intermittent current, one caused by alternatively opening
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  Speaker 1: and closing the circuit, could not be made under any
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  Speaker 1: circumstances to reproduce the delicate forms of the air vibrations
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  Speaker 1: caused by the human voice in articulate speech, but that
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  Speaker 1: the true way was to operate on an unbroken current
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  Speaker 1: by increasing and diminishing its intensity. Such was his discovery,
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  Speaker 1: and it was new. Reese never thought of it, and
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  Speaker 1: he failed to transmit speech telegraphically. Bell did, and he
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  Speaker 1: succeeded Under such circumstances, it is impossible to hold that
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  Speaker 1: what Reese did was an anticipation of the discovery of Bell.
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  Speaker 1: To follow Reese is to fail, but to follow Bell
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  Speaker 1: is to succeed. The difference between the two is just
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  Speaker 1: the difference between failure and success. A very interesting fact,
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  Speaker 1: and one which might have changed the entire commercial status
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  Speaker 1: of the telephone industry, is that in eighteen sixty eight,
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  Speaker 1: Royal e House of Binghamton, New York, invented and patented
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  Speaker 1: an electrophonetic telegraph which was capable of operating as a
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  Speaker 1: magneto telephone in the same manner as the instrument's subsequently
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  Speaker 1: devised by Bell. House knew nothing of its capabilities, however,
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  Speaker 1: unfortunately for him, the instrument is provided with a sounding
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  Speaker 1: diaphragm of pine wood, stiffened with varnish, mounted in one
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  Speaker 1: end of a large sound amplifying chamber, so formed as
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  Speaker 1: to focus the sound waves at a point near its
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  Speaker 1: mouth where the ear was to be placed to receive them.
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  Speaker 1: The electromagnet, adapted to be connected in the line circuit,
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  Speaker 1: had its armature connected by a rod with the center
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  Speaker 1: of the wooden diaphragm. By this means any movements imparted
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  Speaker 1: to the armature by fluctuating currents in the line were
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  Speaker 1: transmitted to the diaphragm, causing it to give out corresponding sounds,
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  Speaker 1: and any movements imparted to the diaphragm by sound waves
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  Speaker 1: were transmitted to the armature, causing its movements to induce
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  Speaker 1: corresponding currents and the line. Two of these instruments, connected
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  Speaker 1: in a circuit would act alternately as transmitters and receivers
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  Speaker 1: in the same manner as Bell's instruments. It has been
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  Speaker 1: shown that in order to transmit speech by electricity, it
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  Speaker 1: is necessary to cause an undulatory or alternating current to
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  Speaker 1: flow in the circuit over which the transmission is to
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  Speaker 1: be effected, and that the strength of this current at
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  Speaker 1: all times be in exact accordance with the vibratory movements
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  Speaker 1: of the body producing the sound. Bell's magnetic transmitter was
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  Speaker 1: used as the generator of this current, as a dynamo.
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  Speaker 1: In fact, the energy for driving which was derived from
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  Speaker 1: the sound waves set up by the voice. The amount
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  Speaker 1: of energy so derived was however, necessarily very small and
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  Speaker 1: the current correspondingly weak, and for this reason was not
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  Speaker 1: a practical form of transmitter except for comparatively short lines.
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  Speaker 1: Elisha Gray devised a transmitter which, instead of generating the
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  Speaker 1: undulatory current itself, depended for its action on causing variation
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  Speaker 1: in the strength of a current generated by some separate source.
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  Speaker 1: This variation and current strength always being in accordance with
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  Speaker 1: the movement of the diaphragm. He mounted on his horizontal
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  Speaker 1: vibrating diaphragm a metal needle extending into a fluid of
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  Speaker 1: low conductivity, such as water. The needle formed one terminal
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  Speaker 1: of the circuit, the other terminal being a metal pin
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  Speaker 1: extending up through the bottom of the containing vessel. The
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  Speaker 1: vibrations of the diaphragm was supposed to cause changes in
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  Speaker 1: the resistance of the path through the fluid on account
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  Speaker 1: of the varying distance between the points of the electrodes,
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  Speaker 1: and therefore corresponding changes in the strength of the current.
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  Speaker 1: Bell also used a liquid transmitter, in which a conducting
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  Speaker 1: liquid was held in a conducting vessel, forming one terminal
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  Speaker 1: of the circuit. The other terminal was a short metallic
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  Speaker 1: needle carried on the diaphragm and projecting slightly into the liquid,
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  Speaker 1: so that the area of contact between the liquid and
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  Speaker 1: the needle would be varied to better advantage by the
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  Speaker 1: vibration of the diaphragm than if the needle were immersed
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  Speaker 1: a greater distance into the fluid. Bell's liquid transmitter depended
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  Speaker 1: on variation in the extent of immersion of the electrode,
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  Speaker 1: while Gray's instrument, owing to the great extent to which
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  Speaker 1: the pin was immersed, depended rather on the variation and
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  Speaker 1: the length of the conducting path through the liquid itself,
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  Speaker 1: a faulty principle for this purpose. Bell's liquid transmitter was
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  Speaker 1: also exhibited at the Philadelphia Centennial in eighteen seventy six, and,
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  Speaker 1: unlike that of Reese, simply caused variations in the resistance
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  Speaker 1: of the circuit, and thereby allowed a continuous but undulatory
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  Speaker 1: current to pass over the line, the variations in which
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  Speaker 1: were able to reproduce all the delicate shades of timber,
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  Speaker 1: loudness and pitch necessary inarticulate speech. Gray and Bell in
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  Speaker 1: bodied or attempted to embody in these instruments. The main
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  Speaker 1: principle upon which all successful battery transmitters are based. A
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  Speaker 1: battery furnished the current and the transmitter actuated by the
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  Speaker 1: voice served to modulate it. It was not long, however,
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  Speaker 1: before a much better means was devised for putting this
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  Speaker 1: principle into practice. End of Section twenty six