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<v Speaker 1>Section thirty of the Science History of the Universe, Volume three.

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<v Speaker 1>This is a LibriVox recording. All LibriVox recordings are in

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<v Speaker 1>the public domain. For more information or to volunteer, please

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<v Speaker 1>visit LibriVox dot org. The Science History of the Universe,

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<v Speaker 1>Volume three, edited by Francis Rolt Wheeler Electricity, Chapter ten

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<v Speaker 1>the Electromagnetic Telegraph, Part two. As the popularity of the

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<v Speaker 1>telegraph increased and the number of line wires grew large,

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<v Speaker 1>attempts were made to make one line wire transmit more

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<v Speaker 1>than one message at the same time. Various schemes have

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<v Speaker 1>been tried, most of which have failed by reason of

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<v Speaker 1>the complications of the apparatus and the subsequent troubles attending them.

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<v Speaker 1>The step in the direction of utilizing the line wire

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<v Speaker 1>more fully was the invention of the duplex system by

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<v Speaker 1>doctor Wilhelm Genthel in eighteen fifty three. This system was

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<v Speaker 1>improved by Carl Friskin of Hanover until it lacked only

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<v Speaker 1>one essential element, means to overcome the condenser like action

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<v Speaker 1>of the long line wire. It was not until eighteen

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<v Speaker 1>seventy two that this was supplied by Joseph B. Stearns

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<v Speaker 1>of Boston, who introduced a condenser into the artificial line

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<v Speaker 1>of the duplex system, and by adjusting it made the

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<v Speaker 1>artificial line behave like the line wire itself. This important

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<v Speaker 1>edition made the system entirely successful, so that it became

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<v Speaker 1>possible to transmit two messages in opposite directions at the

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<v Speaker 1>same time. Following the success of the duplex system, there

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<v Speaker 1>was developed a method by which two messages could be

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<v Speaker 1>sent simultaneously in the same direction, and it was but

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<v Speaker 1>a step to combine these two systems so that two

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<v Speaker 1>messages could be sent each way simultaneously. This last is

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<v Speaker 1>known as the quadruplex system and was immediately successful because

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<v Speaker 1>there were no delicate adjustments to be made and no

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<v Speaker 1>rotating parts as in some of the synchronous telegraphs which

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<v Speaker 1>have been tried from time to time. As early as

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<v Speaker 1>eighteen fifty two, Moses G. Farmer of Salem, Massachusetts devised

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<v Speaker 1>a synchronous multiple telegraph in which he proposed to employ

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<v Speaker 1>two rotating switches, one at each end of the line,

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<v Speaker 1>to successively and simultaneously join the several operators at one

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<v Speaker 1>station with those of another. The idea was to connect

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<v Speaker 1>two operators for an instant pass on to the next

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<v Speaker 1>two and so on, returning to the first two operators

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<v Speaker 1>so quickly that the relay of the receiving operator would

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<v Speaker 1>not have had time to change, nor the key of

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<v Speaker 1>the sender to make a dot. The impulses of the

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<v Speaker 1>current had therefore to be made with great frequency, and

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<v Speaker 1>the control of this impulsive current was the principal cause

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<v Speaker 1>of failure. Another difficulty was the main time of the

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<v Speaker 1>rotating switches in synchronism. The public is occasionally startled with

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<v Speaker 1>an announcement that someone has invented a telegraph by which

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<v Speaker 1>a wire may be utilized for twenty or perhaps forty transmissions,

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<v Speaker 1>but usually it is the old wanderer in a new Garb.

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<v Speaker 1>Speed by this method, however, is limited far Within the

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<v Speaker 1>bounds of these statements, it might seem that it would

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<v Speaker 1>be only necessary to multiply the number of contacts and

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<v Speaker 1>to increase the velocity of the rotating arms, but the

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<v Speaker 1>limit in this direction is soon reached, for only a

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<v Speaker 1>certain number of impulses can be transmitted over a line

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<v Speaker 1>within a certain period with force sufficient to produce signals.

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<v Speaker 1>Many valuable improvements have been made in recent years in

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<v Speaker 1>this class of telegraphy, but large as the art has grown.

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<v Speaker 1>The great object of all has been to obtain more

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<v Speaker 1>perfect synchronism, that is to say, to cause two mechanically

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<v Speaker 1>independent arms to rotate at the same speed. One of

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<v Speaker 1>the most recent of these synchronous telegraphs, and which is

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<v Speaker 1>now being exploited, is that invented by mister Delaney. The

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<v Speaker 1>principle is that of Farmer, but the method used to

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<v Speaker 1>hold the rotating switches in synchronism is extremely ingenious. It

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<v Speaker 1>is stated that one thousand words permitted may be transmitted

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<v Speaker 1>over a single wire. The messages are prepared on a

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<v Speaker 1>tape by a punching machine and received on a chemically

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<v Speaker 1>prepared strip of paper. The idea of printing the dispatch

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<v Speaker 1>is not new. In the early days of the electric telegraph,

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<v Speaker 1>eighteen forty one, Wheatstone took out a patent for printing

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<v Speaker 1>the message in ordinary letters upon a strip of paper.

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<v Speaker 1>Since then, many inventors have followed out the same idea

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<v Speaker 1>with more or less success. The most perfect of all

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<v Speaker 1>these systems, however, is that invented by Professor David E. Hughes,

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<v Speaker 1>which in a modified form is now very generally used

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<v Speaker 1>as a news or stock ticker. Figure forty five shows

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<v Speaker 1>the connections. For s such a telegraph, the sending station

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<v Speaker 1>is at A and one of the receiving stations is

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<v Speaker 1>at B. The line is fed with an alternating current

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<v Speaker 1>produced by reversing commutator four. This alternating current does not

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<v Speaker 1>affect printing relay five, but does operate polar relay six,

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<v Speaker 1>which in turn operates the escapement. Reverser four is driven

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<v Speaker 1>by constant speed motor one and has as many segments

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<v Speaker 1>as there are characters on the type wheel. The escape

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<v Speaker 1>wheel ten is provided with an equal number of teeth,

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<v Speaker 1>so that each revolution of reverser four will produce one

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<v Speaker 1>revolution of type wheel seven. On the shaft with the

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<v Speaker 1>reverser is rigidly mounted a cylinder provided with a number

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<v Speaker 1>of pins arranged spirally as shown. Each pin is in

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<v Speaker 1>line with a segment of the reverser and also in

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<v Speaker 1>line with a pin fastened to the keyboard. Depressing a

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<v Speaker 1>given key will always stop the cylinder and therefore type

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<v Speaker 1>wheel seven in the same place. The connection to the

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<v Speaker 1>motor one is made with friction clutch two, which slips

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<v Speaker 1>when cylinder three is stopped. Now it is evident if

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<v Speaker 1>type wheel seven is started with its characters in certain

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<v Speaker 1>position and is rotated by a motor through gear eleven

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<v Speaker 1>and controlled by escapement magnet six, that it will always

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<v Speaker 1>remain in the same relative position with cylinder three, and

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<v Speaker 1>that the operator can stop the type wheel in any

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<v Speaker 1>desired position. If the type wheel stops because of the

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<v Speaker 1>arrest of the cylinder three by depression of a key,

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<v Speaker 1>the current ceases to alternate, and magnet five has time

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<v Speaker 1>to draw up its armature eight and press the tape

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<v Speaker 1>against the type wheel, thus printing the character which corresponds

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<v Speaker 1>to key depressed at the sending station. These are ingenious

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<v Speaker 1>arrangements for reproducing at a distant point handwriting drawings, et cetera.

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<v Speaker 1>One of the first of these is known as Casselli's

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<v Speaker 1>pen telegraph, because as the reproduction may be of the

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<v Speaker 1>same size or even larger than the original. The message

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<v Speaker 1>to be sent is written with an insulating ink on

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<v Speaker 1>a piece of tinfoil and received on a sheet of

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<v Speaker 1>chemically prepared paper upon which a blue dot is left

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<v Speaker 1>at each current impulse. The motions of the marking style

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<v Speaker 1>at the two stations are controlled by similar pendulums. In

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<v Speaker 1>the Denisen system, these pendulums are forced to vibrate together

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<v Speaker 1>through the control of electro magnets operated by the same

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<v Speaker 1>alternating current. The most recent and useful of these arrangements

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<v Speaker 1>is the telautograph. The message is reproduced as fast as

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<v Speaker 1>it is written. Drawings or sketches are transmitted with great accuracy.

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<v Speaker 1>In fact, every motion of the sending pen is instantly

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<v Speaker 1>followed by the receiver. Some of these are in use

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<v Speaker 1>in the United States Army. The insulation of conductors for

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<v Speaker 1>use under water was made possible by the discovery of

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<v Speaker 1>Guda percha by an ink English surgeon in India in

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<v Speaker 1>eighteen forty two. It is extremely probable that the widespread

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<v Speaker 1>use of submarine cables would have been postponed many years

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<v Speaker 1>had this substance remain unknown. One of the first cables

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<v Speaker 1>insulated by this material, and possibly the very first, was

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<v Speaker 1>laid in eighteen forty eight across the Hudson River from

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<v Speaker 1>Jersey City to New York. In eighteen fifty a cable

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<v Speaker 1>was laid across the channel from Dover to Calais, but

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<v Speaker 1>it was unprotected by any sheathing or armour, and it

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<v Speaker 1>lasted but a single day. In the following year, the

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<v Speaker 1>experiment was repeated, this time with a cable protected by

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<v Speaker 1>a number of heavy iron wires. The operation was successful,

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<v Speaker 1>and permanent telegraph communication was established. During the next few years,

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<v Speaker 1>the number of submarine cables increased rapidly, as did also

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<v Speaker 1>their length, although on account of ignorance in regard to

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<v Speaker 1>many conditions necessary to ensure the best success, failures were numerous.

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<v Speaker 1>Many people began to consider the feasibility of a line

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<v Speaker 1>connecting the continents across the Atlantic Ocean. A few sanguine

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<v Speaker 1>capitalists combined to further the enterprise, and through the undaunted

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<v Speaker 1>courage and faith of an American mister Cyrus W. Field,

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<v Speaker 1>the purely financial obstacles were surmounted. Unfortunately, the electrical and

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<v Speaker 1>engineering problems to be met with were not understood, and

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<v Speaker 1>the first cable of eighteen fifty eight, after gasping for

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<v Speaker 1>breath for a few short weeks, lay dumb forever at

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<v Speaker 1>the bottom of the sea. Something of the character of

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<v Speaker 1>this cable may be learned from the following brief description

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<v Speaker 1>by Sir William Thompson, to whom, more than to any

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<v Speaker 1>other one man the world is indebted for the success

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<v Speaker 1>of submarine telegraphy in the year eighteen fifty seven. As

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<v Speaker 1>much iron as would make a cube twenty feet wide

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<v Speaker 1>was drawn into wire long enough to extend from the

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<v Speaker 1>Earth to the moon and bind several times around each globe.

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<v Speaker 1>This wire was made into one hundred and twenty six

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<v Speaker 1>lengths of two thousand, five hundred miles and spun into

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<v Speaker 1>eighteen strands of seven wires each A single strand of

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<v Speaker 1>seven copper wires of the same length, weighing in all

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<v Speaker 1>one hundred and ten grains per foot, was three times

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<v Speaker 1>coated with Gudha percha to an entire outer thickness of

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<v Speaker 1>zero point four of an inch, and this was served

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<v Speaker 1>outside with two hundred and forty tons of tarred yarn,

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<v Speaker 1>and then laid over with the eighteen strands of iron

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<v Speaker 1>wire in long continuous spirals, and passed through a bath

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<v Speaker 1>of melted pitch. An attempt to lay this cable in

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<v Speaker 1>eighteen fifty seven resulted in the loss of four hundred

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<v Speaker 1>or five hundred miles by breaking from the stern of

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<v Speaker 1>the ship from which it was run. After some further experimentation,

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<v Speaker 1>it was determined to employ two ships to lay it

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<v Speaker 1>in the following year, and accordingly, on the twenty ninth

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<v Speaker 1>of July eighteen fifty eight, the Niagara and the Agamemnon,

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<v Speaker 1>each loaded with half the cable, met in mid ocean,

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<v Speaker 1>joined the ends and started the Niagara for the west

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<v Speaker 1>and the Agamemnon for the east. On the fifth of August,

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<v Speaker 1>the ends were successfully landed on the opposite shores of

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<v Speaker 1>the Atlantic. The cable was known to be in bad

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<v Speaker 1>condition before the laying was completed, and the earnest but

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<v Speaker 1>ill advised efforts which were made to force it to

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<v Speaker 1>work during its brief period of activity only tended to

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<v Speaker 1>shorten its life. Communication of a very irregular and unsatisfactory

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<v Speaker 1>character was maintained for several weeks. The admirable mirror galvanometer,

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<v Speaker 1>which had just been devised by Sir William Thompson, was

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<v Speaker 1>for the first time in use at the Valencia end,

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<v Speaker 1>while for a time the attempt was made to use

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<v Speaker 1>the ordinary receiving apparatus which had been provided by the

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<v Speaker 1>company at Newfoundland. Later the galvanometer was put in use

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<v Speaker 1>on this side, but not before very powerful currents had

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<v Speaker 1>been used on the cable. In fact, Sir William Thompson

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<v Speaker 1>has declared his belief that if proper methods of handling

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<v Speaker 1>the cable electrically had been in use, from the beginning,

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<v Speaker 1>its performance would have been lasting and in the main satisfactory.

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<v Speaker 1>Owing to the fragmentary character of many of the messages transmitted,

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<v Speaker 1>a single sentence from that of the Queen to the

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<v Speaker 1>President having been received on August sixteenth, and the remainder

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<v Speaker 1>twenty four hours later. Many persons in both Europe and

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<v Speaker 1>America became skeptical as to the transmission of signals, and

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<v Speaker 1>not a few even doubted that the cable had been laid.

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<v Speaker 1>As a matter of fact, four hundred messages containing over

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<v Speaker 1>four thousand words were sent. On September. First interchange of

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<v Speaker 1>messages ceased, but on October twentieth the cable spoke its

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<v Speaker 1>last words, two hundred for which were read at Valencia,

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<v Speaker 1>being part of a message giving the number of battery

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<v Speaker 1>cells then on the line. From that date, the splendid

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<v Speaker 1>combination of matter lay at the bottom of the sea,

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<v Speaker 1>forever useless. But it had not lived in vain. The

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<v Speaker 1>possibility of the thing was demonstrated, and it only remained

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<v Speaker 1>to surmount the obstacles which this trial had shown. During

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<v Speaker 1>a few years succeeding this first attempt, the problem was

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<v Speaker 1>studied in the light of the experience which it had afforded.

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<v Speaker 1>Another trial was made in eighteen sixty five, this time

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<v Speaker 1>by the Great Eastern, a vessel, which offered many advantages

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<v Speaker 1>for cable laying. After about two thirds of the distance

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<v Speaker 1>was run, the cable broke and further operations were postponed

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<v Speaker 1>until the following year, when a complete cable was successfully laid,

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<v Speaker 1>and that of eighteen sixty five picked up, spliced and finished.

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<v Speaker 1>Since then other lines had been placed across the Atlantic,

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<v Speaker 1>and now the operations of laying an ocean cable attracts

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<v Speaker 1>no attention. One of the difficulties encountered in attempting to

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<v Speaker 1>send messages through such a long cable was that, due

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<v Speaker 1>to the electrostatic capacity of the cable, the cable acts

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<v Speaker 1>like a very large condenser, so that when the voltage

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<v Speaker 1>is applied at one end, the current does not instantly

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<v Speaker 1>rise to its steady value, but takes several seconds, and

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<v Speaker 1>when the supply of voltage is disconnected, the current continues

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<v Speaker 1>to flow in order to signal rapidly. Therefore, it was

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<v Speaker 1>necessary to overcome this action and to use very delicate

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<v Speaker 1>receiving instruments for this purpose. Sir William Thompson, Lord Kelvin

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<v Speaker 1>devised the well known siphon recorder, which is really a

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<v Speaker 1>sensitive galvanometer whose moving coil carries a siphon tube filled

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<v Speaker 1>with ink, the ink being ejected from it in fine

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<v Speaker 1>drops on a strip of paper. To produce these fine drops,

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<v Speaker 1>the siphon tube is connected to a small electrostatic machine

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<v Speaker 1>so that the tube is allow Although the telephone has

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<v Speaker 1>made such rapid advances as a means of communication, the

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<v Speaker 1>telegraph still holds its own field. The greater simplicity of

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<v Speaker 1>the latter, the less expensive lines, the greater distances to

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<v Speaker 1>which messages can be transmitted, all combined for its preservation.

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<v Speaker 1>The flattening out of the waves on a telephone line

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<v Speaker 1>due to the condenser like action of the line has

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<v Speaker 1>not yet been overcome. The difference between the telephonic waves

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<v Speaker 1>at the beginning and end of a line may be

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<v Speaker 1>compared to that between the noisy exhaust of an automobile

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<v Speaker 1>motor without and with a muffler. In the case of

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<v Speaker 1>the transmission of telephone waves, it is therefore a problem

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<v Speaker 1>of how to rid the line of its muffler. End

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<v Speaker 1>of Section thirty