Latest / History of the Universe Physics & Electricity Vol. 3 / 029 - Electricity - Chapter 10 - The Electro-Magnetic Telegraph Part 1

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029 - Electricity - Chapter 10 - The Electro-Magnetic Telegraph Part 1 · History of the Universe Physics & Electricity Vol. 3

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Speaker 1: Section twenty nine of the Science History of the Universe,
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Speaker 1: Volume three. This is a LibriVox recording. All LibriVox recordings
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Speaker 1: are in the public domain. For more information or to volunteer,
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Speaker 1: please 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 ten
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Speaker 1: the electromagnetic Telegraph, Part one. As early as seventeen seventy four,
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Speaker 1: Le Sage constructed an electric telegraph consisting of twenty four wires,
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Speaker 1: at the end of each of which was a pith
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Speaker 1: ball electroscope, and in eighteen sixteen ronalds constructed a line
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Speaker 1: of one wire using pithballs and two synchronous wheels. He
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Speaker 1: endeavored to bring the matter to the attention of the
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Speaker 1: British government, and received the really exquisite reply that telegraphs
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Speaker 1: of any kind are now wholly unknown necessary, and no
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Speaker 1: other than the one now in use will be adopted.
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Speaker 1: A very important step was taken in eighteen twenty eight
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Speaker 1: by Harrison Gray Dyer of New York, who invented a
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Speaker 1: method of recording in which a discharge was made to
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Speaker 1: pass through a sheet of moisten litmus paper moving at
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Speaker 1: a uniform rate. A line was actually set up and
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Speaker 1: experimented upon in the same year. In all of these
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Speaker 1: systems it was proposed to use frictional electricity, but even
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Speaker 1: with the present vastly increased power of production and control
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Speaker 1: of this species of electricity, a successfully operating telegraph would
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Speaker 1: hardly be possible. The real electric telegraph began with Galvani
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Speaker 1: and Volta, and as already intimated, more than one system
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Speaker 1: has been fairly successful, the fundamental principles of which were
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Speaker 1: understood before the close of the first decade of the
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Speaker 1: present century. The complete solution of the problem, however, unquestionably
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Speaker 1: have been postponed for many years but for the discovery
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Speaker 1: of Orsted in eighteen twenty. Immediately on its announcement, the
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Speaker 1: telegraph became the dream of many men in many countries.
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Speaker 1: Concerning its origin and growth, says T. C. Mendenhall in
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Speaker 1: his Century of Electricity, the great majority of Americans have
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Speaker 1: been singularly mistaken. The popular impression seems to be that
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Speaker 1: it is exclusively an American invention, and that in America
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Speaker 1: it was almost exclusively the product of the genius of
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Speaker 1: one man. It hardly need be said that these impressions
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Speaker 1: are extremely erroneous, and Pierre, whose genius had accomplished so
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Speaker 1: much in the early development of the theory of electromagnetism,
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Speaker 1: was probably the first to suggest its use in telegraphy.
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Speaker 1: His method was founded on Orsted's experiment. If a needle
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Speaker 1: could be deflected by an electric current, if this could
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Speaker 1: be amplished by a wire or wires of great length,
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Speaker 1: and if these movements of the needle could be converted
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Speaker 1: into a code by means of which letters or words
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Speaker 1: could be expressed, then the electromagnetic telegraph was possible. Ampierre's
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Speaker 1: suggestion was to employ a number of wires and to
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Speaker 1: deflect a number of needles. Considerable attention was given to
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Speaker 1: the development of this idea for a number of years
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Speaker 1: following the discovery of its fundamental principle. The progress of
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Speaker 1: the invention was seriously retarded by the publication of an
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Speaker 1: investigation by Barlow of the Woolrich Military Academy in eighteen
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Speaker 1: twenty five, in the course of which he discovered that
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Speaker 1: there was an enormous diminuation in the power of a
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Speaker 1: current to produce effects with an increase of distance, and
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Speaker 1: which led him to declare that the project of an
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Speaker 1: electromagnetic telegraph could not possibly be successful. The invention of
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Speaker 1: the electro magnet by Sturgeon A. Carently offered a new
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Speaker 1: solution of the problem, but owing to the imperfect construction
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Speaker 1: of his magnets, the difficulty of overcoming distance was not diminished.
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Speaker 1: This obstacle, which seems for a time to be insurmountable,
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Speaker 1: was conquered by Joseph Henry in the manner already described.
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Speaker 1: Out of Orsted's experiment grew the needle telegraph, a form
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Speaker 1: which prevailed for several years in Europe until it gave
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Speaker 1: way before the evidence superiority of that founded on the
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Speaker 1: electro magnet, which grew out of the researches of Henry,
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Speaker 1: and which is generally known as the Morse or American system.
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Speaker 1: The needle telegraph was first in the field, and its
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Speaker 1: working will first be considered. Many of its earlier forms
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Speaker 1: appear as suggestions, only, no attempt having been made to
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Speaker 1: put them in practical operation. In eighteen thirty two, however,
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Speaker 1: Baron Schilling, a Russian councilor of State, had a working
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Speaker 1: system in which thirty six needles were used, and which
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Speaker 1: included an ingenious alarm for calling the attention of the
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Speaker 1: receiving operator. It consisted of a device by means of
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Speaker 1: which the movement of one of the needles released a
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Speaker 1: small ball of lead, which, by dropping upon the mechanism
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Speaker 1: of the alarm, set it in operation. A model of
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Speaker 1: this system was exhibited before the Emperors Alexander and Nicholas.
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Speaker 1: A little later, the two illustrious German philosophers Gauss and
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Speaker 1: Weber established a successfully operating line at Gottenngen. It was
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Speaker 1: two or three miles long and a double wire was used.
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Speaker 1: Magnetic needles or bars freely suspended were used as receiving instruments,
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Speaker 1: and the arrangement included a device for setting off an
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Speaker 1: alarm clock. The current from a battery was first used,
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Speaker 1: but afterward the secondary or induced current was substituted. This
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Speaker 1: line was in working order in eighteen thirty three and
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Speaker 1: was established mainly for experimental purposes. The practical development of
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Speaker 1: the scheme was given over to Steinheil, in whose hands
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Speaker 1: it grew with rapidity. In eighteen thirty seven he had
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Speaker 1: constructed several miles of telegraph extending from Munich to various
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Speaker 1: points in the vicinity. His work appears to have been
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Speaker 1: officially sanctioned by the government, and his wires doubtless constituted
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Speaker 1: the first electric telegraph ever erected for commercial purposes. The
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Speaker 1: system included a method of recording the message as received,
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Speaker 1: which might also be read by sound, the signals being
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Speaker 1: distinguished from each other by the use of bells differing
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Speaker 1: in pitch. But altogether, the most valuable contribution made by Steinheil,
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Speaker 1: says Mendenhall, was the discovery that the use of a
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Speaker 1: double wire was unnecessary, it being possible to establish electric
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Speaker 1: communication between two points by the use of one wire,
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Speaker 1: whose terminals were joined to the earth through plates of
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Speaker 1: metal or other conductors, exposing considerable sir as it largely
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Speaker 1: reduced the cost of construction. This discovery was of prime importance.
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Speaker 1: It was really a repetition of what Franklin had long
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Speaker 1: before accomplished when he stretched his wire across the Schoolkill River,
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Speaker 1: but the relation between the two experiments was not at
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Speaker 1: the time appreciated or fully understood. Both the science of
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Speaker 1: electricity and the art of telegraphy owe much to the
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Speaker 1: genius of Sir Charles Wheatstone, whose interest in and connection
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Speaker 1: with telegraph enterprises began in eighteen thirty five, in which
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Speaker 1: year he exhibited one of Schilling's telegraphs in his lectures,
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Speaker 1: and in the year eighteen thirty seven, when he formed
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Speaker 1: a co partnership with W. F. Cook for the purpose
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Speaker 1: of introducing the electric telegraph into England. Their first patent
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Speaker 1: was taken out in eighteen thirty seven, and the system
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Speaker 1: required five needles with as many wires for their manipulation
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Speaker 1: and a sixth wire for the return current. Wheatstone developed
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Speaker 1: numerous improvements during the next few years, and as early
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Speaker 1: as eighteen forty a dial instrument showing the letters of
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Speaker 1: the alphabet was patent. Numerous difficulties were encountered and overcome,
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Speaker 1: and by eighteen forty four the enterprise was on a
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Speaker 1: sound financial basis. The operation of working a telegraph was
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Speaker 1: at first naturally regarded by most people as a mystery
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Speaker 1: and by many as a fraud. When communication was established
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Speaker 1: between Paddington and Slew, a distance of about twenty miles,
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Speaker 1: The wires were insulated partly by silk and were suspended
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Speaker 1: through goose quills attached to posts along the Great Western Railroad.
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Speaker 1: The telegraph Company not only invited the patronage of the
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Speaker 1: public in a legitimate business way, but it also exhibited
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Speaker 1: its apparatus as a novelty. This short line speedily established
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Speaker 1: itself in the good graces of the people through its
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Speaker 1: instrumentality in securing the arrest of a criminal. The construction
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Speaker 1: expenses incident to the use of a large number of wires,
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Speaker 1: to say nothing of other difficulties, led to the reduction
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Speaker 1: of the number of needles employed to two and one
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Speaker 1: in which a single wire was sufficient. A single needle
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Speaker 1: is now almost universally employed wherever the needle system has
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Speaker 1: survived competition with other forms. The movements of the needle
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Speaker 1: are readily applied to signaling the alphabet by combinations of
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Speaker 1: swings to the right and to the left. It will
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Speaker 1: be remembered that in Orsted's experiment, a reversal of the
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Speaker 1: current through the wire reversed the direction of the deflection
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Speaker 1: of the needle. The operating key is so arranged that
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Speaker 1: when its handle is turned to the right, a current
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Speaker 1: is sent through the line, which deflects the needle in
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Speaker 1: the same direction, and when the opposite movement is made,
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Speaker 1: the current is reversed and the needle swings to the left.
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Speaker 1: The alphabet may and generally does correspond with what is
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Speaker 1: known as the Morse code. A swing to the the
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Speaker 1: right is interpreted as a long signal or dash, and
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Speaker 1: one to the left as the short or dot signal
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Speaker 1: of the Morse system. For many years, the needle system
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Speaker 1: of telegraph was used almost exclusively in Great Britain, although
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Speaker 1: it never succeeded in gaining a foothold on the continent
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Speaker 1: of Europe or in any other part of the world.
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Speaker 1: Its principal advantage is the comparatively feeble current required to
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Speaker 1: work it. But it is slower than the Morse system
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Speaker 1: and does not lend itself to sound reading or to
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Speaker 1: methods of securing written records of the messages which it transmits.
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Speaker 1: It has therefore almost entirely given way to other systems,
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Speaker 1: even in Great Britain, although as will be seen, it
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Speaker 1: is retained in connection with long ocean cables, and within
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Speaker 1: a few years a self recording device has been successfully
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Speaker 1: applied to it. The system of telegraphy, now almost universally
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Speaker 1: in use is one which originated in America, and whose
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Speaker 1: development was nearly temporaneous with that of the needle system
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Speaker 1: in England. The fundamental experiment about which the telegraph grew
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Speaker 1: was that of Orsted, while in America the electro magnet,
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Speaker 1: as constructed by Sturgeon and improved by Henry, was made
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Speaker 1: the basis of the invention. As there has been much
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Speaker 1: misunderstanding concerning the distribution of credit for the evolution of
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Speaker 1: this system of telegraphy, it may not be out of
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Speaker 1: the way to consider at some length its important phases.
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Speaker 1: Much credit must always be accorded Professor S. F. B. Morse,
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Speaker 1: through whose indefatigable labours and persistent faith, the commercial value
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Speaker 1: of the enterprise was first established. Born in the last century,
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Speaker 1: he reached the age of forty years before having apparently
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Speaker 1: given a single thought to what was to be the
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Speaker 1: great work of his life. His early training was that
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Speaker 1: of an artist, although he was always fond of scientific pursuits.
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Speaker 1: He studied in London under the best man masters, and
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Speaker 1: was highly successful in his chosen profession, some of his
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Speaker 1: works bringing him great renown. His first conception of an
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Speaker 1: electromagnetic telegraph seems to have arisen out of a conversation
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Speaker 1: with a friend on board the packet ship Sully, a
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Speaker 1: voyage from harv to New York in eighteen thirty two.
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Speaker 1: In this conversation, some experiments of the French were described
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Speaker 1: in which electricity had been transmitted through long distances. Someone remarked,
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Speaker 1: it would be well if we could send news in
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Speaker 1: this rapid manner, to which Morse at once replied, why
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Speaker 1: can't we? And from that moment he devoted his energies
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Speaker 1: to accomplishing the desired end. During the remainder of the voyage,
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Speaker 1: he made drawings of forms of apparatus and considered the
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Speaker 1: transmission of signals into an alphabet. He does not appear
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Speaker 1: to have been familiar with the principles of electromagnetism at
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Speaker 1: that time, and it is affirmed that the use of
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Speaker 1: an alone intro magnet was suggested to him by the
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Speaker 1: gentleman with whom this first discussion was held. On reaching
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Speaker 1: New York, he began experimenting upon the subject, and in
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Speaker 1: eighteen thirty five he had completed a working model of
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Speaker 1: his recording instrument. It was not until eighteen thirty seven, however,
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Speaker 1: that he was able to put two of them in
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Speaker 1: operation at the extremities of a short line, so as
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Speaker 1: to be able to both receive and send signals. In
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Speaker 1: that year, his apparatus was exhibited to many people in
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Speaker 1: the University of New York. In the following year, he
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Speaker 1: made an unsuccessful effort to secure aid from Congress to
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Speaker 1: establish an experimental line between Washington and Baltimore. He then
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Speaker 1: visited Europe, but failed to secure patents for his inventions.
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Speaker 1: During the session of Congress of eighteen forty two to
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Speaker 1: forty three, he again struggled to secure recognition and in
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Speaker 1: appropriation to enable him to build his experimental line. The
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Speaker 1: scheme was considered quixotic by many members of Congress, and
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Speaker 1: at the last moment he despaired of success. But during
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Speaker 1: the midnight hour of the last night of the session,
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Speaker 1: March third, eighteen forty three, a bill was passed appropriating
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Speaker 1: thirty thousand dollars for the line from Washington to Baltimore.
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Speaker 1: In the meantime, many apparently insuperable obstacles had been encountered
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Speaker 1: in the attempt to secure the successful working of the apparatus.
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Speaker 1: In the beginning, Morse used a magnet with a few
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Speaker 1: turns of wire, as Sturgeon had done, and a single
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Speaker 1: cell of battery. With this, his instrument failed to work
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Speaker 1: through more than a few feet of wire. This difficulty
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Speaker 1: was surmounted by taking advantage of the researches of Henry,
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Speaker 1: using what he called an intensity magnet and many cells
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Speaker 1: of battery instead of one. Although by this method signals
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Speaker 1: could be transmitted through a comparatively long distance, they were
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Speaker 1: still too feeble to print themselves upon the moving strip
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Speaker 1: of paper. To overcome this difficulty, it was only necessary
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Speaker 1: to introduce the device known as the relay, by means
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Speaker 1: of which the work on the main circuit was reduced
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Speaker 1: to making and breaking the current of a local battery
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Speaker 1: on the circuit of which was the recording machine. In
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Speaker 1: this short circuit, the current was easily made strong enough
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Speaker 1: to operate the registering instrument. This method of working had
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Speaker 1: been devised nearly ten years before by Henry, and it
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Speaker 1: had also been used by Wheatstone in his needle system.
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Speaker 1: In Morse's first attempt to build his experimental line from
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Speaker 1: Washington to Baltimore in eighteen forty four, the wires were
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Speaker 1: placed underground instead of upon polls, but the former method
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Speaker 1: was soon abandoned for the latter, which had already been
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Speaker 1: in use for several years in Europe and elsewhere. In
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Speaker 1: Morse's first instrument, the transmitter was mechanical, that is, to say,
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Speaker 1: the message to be sent was first set up in
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Speaker 1: dots and dashes by arranging long and short type in
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Speaker 1: proper order in a line, and by the regular movement
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Speaker 1: of this line of type. The current was closed for
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Speaker 1: periods of time necessary for the reproduction of the dots
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Speaker 1: and dashes at the other end, Morse did not imagine
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Speaker 1: that signals could be made by the hand with sufficient
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Speaker 1: regularity to produce legible records. This was soon discovered to
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Speaker 1: be possible, however, and for the clumsy mechanical transmitter, the
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Speaker 1: simple key in use today was substituted by the skillful
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Speaker 1: manipulation of which the operator produces dots and dashes with
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Speaker 1: such regularity and rapidity as to leave nothing to be desired.
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Speaker 1: The statements made above, derived from papers of an official character,
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Speaker 1: may be summarized as follows. In the Morse Telegraph are
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Speaker 1: found the battery for which credit must be given primarily
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Speaker 1: to Volta, and then to Daniel, who in eighteen thirty
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Speaker 1: six devised a battery nearly constant in its strength, an
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Speaker 1: essential rest requisite to its application to the telegraph. The
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Speaker 1: key or transmitter, which, except in details of construction, is
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Speaker 1: practically that in use since experiments on electricity were begun.
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Speaker 1: The receiving instrument, of which the essential feature is the
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Speaker 1: electro magnet, due primarily to Sturgeon, but modified and improved
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Speaker 1: so as to be available for this work by Henry.
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Speaker 1: The relay by means of which the local current is
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Speaker 1: put in operation, which was used by Henry and also
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Speaker 1: by Wheatstone. The line wire suspended on poles, a method
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Speaker 1: first practically used by doctor W. O'shannessee at Calcutta in
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Speaker 1: eighteen thirty nine. While it appears therefore that Morse cannot
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Speaker 1: justly claim priority in the discovery of a single scientific
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Speaker 1: principle involved in the telegraph, it must be admitted on
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Speaker 1: all hands that he played a most important part in
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Speaker 1: its development in Europe. All effort had been in the
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Speaker 1: direction of the use the needle system. Morse was quick
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Speaker 1: to see the advantages of the electro magnet, and especially
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Speaker 1: the ease with which it could be made to leave
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Speaker 1: a permanent record of the message. His use of a
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Speaker 1: simple armature with to and fro motion, armed with a
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Speaker 1: style or pencil which marked long or short lines upon
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Speaker 1: a moving slip of paper, and his alphabet made up
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Speaker 1: of these dots and dashes show great ingenuity and mechanical judgment.
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Speaker 1: As a measure of the value of his system compared
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Speaker 1: with the English, it is sufficient to repeat that today
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Speaker 1: it has driven nearly every other from the field. End
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Speaker 1: of Section twenty nine