Part 21

In the following table, the first column represents the keys, which when depressed, produce a deflection of the needles, (represented in the columns, second, third and fourth,) by means of their batteries, and thus closing the circuit of the wires, ̈1, ̈2, ̈3, ̈4, ̈5 and ̈6, by which the fluid, is made to pass through the prepared fabric, and mark upon its space, or spaces, numbered 1, 2, 3, 4, 5 and 6, in the fifth column. In the sixth column are the letters which the marks upon the fabric are intended to represent.

Keys. Needles. Needles. Needles. Spaces on Fabric. Letters. H, 7, A, T, - - 1, A. J, 7, A, S, - - 2, B. K, 7, B, T, - - 3, C. M, 7, B, S, - - 4, D. O, 7, C, T, - - 5, E. U, 7, C, S, - - 6, F. H, K, 7, A, T, B, T, - 1, 3, G. J, M, 7, A, S, B, S, - 2, 4, H. K, O, 7, B, T, C, T, - 3, 5, I. M, U, 7, B, S, C, S, - 4, 6, J. H, O, 7, A, T, C, T, - 1, 5, K. J, U, 7, A, S, C, S, - 2, 6, L. H, M, A, T, B, S, - 1, 4, M. J, K, A, S, B, T, - 2, 3, N. K, U, B, T, C, S, - 3, 6, O. M, O, B, S, C, T, - 4, 5, P. H, U, A, T, C, S, - 1, 6, Q. J, O, A, S, C, T, - 2, 5, R. H, K, O, 7, A, T, B, T, C, T, 1, 3, 5, S. J, M, U, 7, A, S, B, S, C, S, 2, 4, 6, T. H, K, U, A, T, B, T, C, S, 1, 3, 6, U. J, M, O, A, S, B, S, C, T, 2, 4, 5, V. H, M, U, A, T, B, S, C, S, 1, 4, 6, W. J, K, U, A, S, B, T, C, S, 2, 3, 6, X. H, M, O, A, T, B, S, C, T, 1, 4, 5, Y. J, K, O, A, S, B, T, C, T, 2, 3, 5, Z.

_Telegraphic Letters._ 1 · · · · · · · · · 2 · · · · · · · · · 3 · · · · · · · · · 4 · · · · · · · · · 5 · · · · · · · · · 6 · · · · · · · · · A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

The above represents the telegraphic characters marked upon the prepared fabric. The spaces are numbered from the top.

The first six of the telegraphic letters require each a signal wire, and the common wire, D, with one battery.

The next six require each two signal wires, with two batteries, whose joint currents pass in the same direction on the common wire, D.

The next six require each two signal wires only, with two batteries, joined together so as to form a compound battery. The negative pole of one, connected with the positive pole of the other.

The next two require each three signal wires, with three batteries, whose joint currents pass in the same direction along the common wire, D.

The next six require each, three _signal_ wires only, with three batteries. One of the signal wires with its battery is used as a common wire for the other two. Hence the current of the two batteries of the two signal wires unite in one, and are connected with the battery of the common wire as a compound battery.

With what rapidity these letters may be formed, does not appear, or to what extent the plan has been carried out.

_Bain’s Printing Telegraph._

The following description of Mr. Bain’s plan of what he calls an _electro magnetic_ printing telegraph, is taken from a work entitled, “An account of some remarkable applications of the electric fluid to the useful arts, by Alexander Bain. Edited by John Finlaison, Esq. London, 1843.”

It appears from this work that Mr. Bain’s plan was invented in 1840, and the following certificate is given in reference to the date of its first operation.

PERCEIVAL STREET, CLERKENWELL, _Aug. 28, 1842_.

DEAR SIR—In reference to your application, I recollect visiting you at your apartments in Wigmore street, early in July, 1840, when you showed me the model of your _electro magnetic_ printing telegraph, with which you printed my name at the time. You also showed me a model of your electro magnetic clock, and explained to me the principles and utility of them. I remain, dear sir, yours, respectfully, ROBERT C. PINKERTON.

To MR. ALEXANDER BAIN.

Figures 76 and 77 exhibit the arrangements of Mr. Bain’s telegraph. Both figures are the same, representing one as being at _Portsmouth_, and the other at _London_. The same letters will refer to either instrument: _d_, _i_ and _h_, represent the signal dials, insulated from the machine. X is a hand or pointer. The small dots represent twelve holes in the dial, corresponding with the twelve signals, and two blanks, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0. U is a similar hole over the starting point of the hand, X. R is a coil of wire, freely suspended on centres. K and K, is a compound permanent magnet, placed within the coil, and immovably fixed upon the frame of the machine. J and J are sections of similar permanent magnets. S is a spiral spring, (and there is another on the opposite side,) which conveys the electric current to the wire coil, and at the same time leaves the coil free to move in obedience to the magnetic influence. So long as the electricity is passing, the wire coil continues to be deflected, but the instant the electric current is broken, the springs, S, bring back the coil to its _natural position_.[36] L is an arm fixed to, and carried by the wire coil, R and R, to stop the rotation of the machinery. B is a main spring barrel, acting on the train of wheels, G, H and I, which communicate motion to the governor, W, and the hand, X. On the arbor of the wheel, H, is fixed a type wheel, C, at a little distance from the paper cylinder, A, on which the messages are to be imprinted. P is a second main spring barrel, with its train of wheels, M, O. Q, is a fly, or vane. On the arbor of the wheel, _o_, there is a crank, V, and two pallets, _a_ and _b_, which prevent the train of wheels from rotating, by coming in contact with the lever, Z. When the telegraph is not at work, a current of electricity is constantly passing from the _Portsmouth plate_, buried in the ground, through the moisture of the earth, to the plate in the ground at the _London_ station. From the copper plate of that station the electric current passes up through the freely suspended multiplying coil, R and R, (which it deflects to the horizontal position,) into the machinery, and thence to the dial, by means of a metal pin, inserted in the hole, U; from the dial it passes by a single insulated conducting wire, 1, suspended in the air, back to the first machine; traversing which, it passes through the freely suspended multiplied coil, R and R, which it deflects, also, to the horizontal position to the plate from whence it started, and thus completes the circuit.

[36] Mr. Bain means, by the _deflected position_ of the coil, (when the current is passing,) its _horizontal_ position, as shown in the figure. Its _natural_ position, (when the current is broken,) is the elevation of the left hand end of the coil, in the direction of the arrow, carried up by the power of the spring, at the centre of the coil. This action of the spring is overcome, when the current is passing, to such a degree, as to bring the coil to the horizontal position as represented in the figure.

“When a communication is to be transmitted from either end of the line (one station only being able to transmit at a time,) the operator draws out the metal pin from the hole, U, in the dial of his machine; the electric circuit is then broken, and the ends of the multiplying coils, R and R, at both stations are carried upwards, in the direction of the arrow, by the force of the spiral springs. The arms, L, attached to the two coils, moving to the right, release the lever, Y, which leaves the machinery free to rotate, and as the moving and regulating powers are the same at both places,[37] the machines go accurately together; that is, the hands of both machines pass over similar signals at the same _instant_ of time, and similar types are continually brought opposite to the printing cylinders at the same moment. An inspection of the wheel work will show, that this movement will have caused the governor, W, to make several revolutions, and the divergence of the balls, in obedience to centrifugal force, will have raised one end of the lever, Z, and depressed the other, which allows the pallet, _a_, to escape; but the rotation of the arbor is still opposed by contact with the second pallet, _b_. The operator having inserted the metal pin in the hole, under the signal which he wishes to communicate, the moment the hand of the dial comes in contact with it, the circuit is again completed, and both machines are stopped instantly. The governor balls, collapsing, depress the left hand end of the lever, Z, clear the pallet, _b_, and this allows the crank spindle, V, to make one revolution.

[37] It is absolutely necessary to the certain and accurate performance of the two machines, that their movements should be synchronical, or else a different figure, or signal, from that intended by the operator at the transmitting station, may be given at the receiving station.

“The motion of the crank by means of the crank rod, T, acting on the lever, E, presses the type against the paper cylinder, A, and leaves an impress upon the paper; at the same time, a spring, _e_, attached to an arm of the lever, E, takes into a tooth of the small ratchet wheel, D, on the spindle of the long pinion, F, which takes into and drives the cylinder wheel; so that the crank apparatus, going back to its former position, after impressing a letter, moves the signal cylinder forward, and presents a fresh surface to the action of the next type. As the cylinder moves round, it has also a spiral motion upward, which causes the message to be printed in a continuous spiral line until the cylinder is filled.[38] In order to mark, in a distinct and legible manner, the letters printed by the apparatus, two thicknesses of riband, saturated with printing ink and dyed, are supported by two rollers so as to interpose between the type wheel and the cylinder; (the rollers are not shown in the figure, to prevent confusion.) If a second copy of the message, thus simultaneously printed at two distant places, is desired at either, a slip of white paper is placed between the ribands to receive the imprint at the same time as the cylinder.”

[38] This contrivance for moving the paper is exactly similar to that in Prof. Morse’s _first model_ of his telegraph, made in 1837, for the Patent Office.

Figure 78 represents a top view of the coil and magnets of Mr. Bain’s machine. B is the compound permanent magnet, with six bars. N is the north pole, and S the south pole. A, A are the sides of the brass frame containing the coils; C, C are the spiral springs on each side: _a_ and _a_ is the axis of the coil: _o, o_, is a part of the frame containing the clock work, (not shown in this figure,) supporting one centre of the coil, and I and I a support for the other centre. N and P are the wires, one of which is in connection with the ground, and the other with the extended wire. When the circuit is closed, and the current from P pole of the battery is in the direction of the arrow above, and then through the coil to the other pole, N, in the direction of the arrow below; the end, D, of the coil, will be depressed, and the end, U, will rise; reverse the current and the effect is the elevation of the end, D, of the coil, and the depression of the end, U.

_Wheatstone’s Rotating Disc Telegraph, invented, 1841._

Figure 79 represents that portion of the instrument which belongs to the _transmitting_ station, of which, K, is a circular disc, with the alphabet and numerals, marked in two concentric circles upon it: _a_ are handles projecting from its rim, one to every letter, by means of which, the disc is turned upon its axis, and brought to that position, _b_, required for signalizing a letter. O is a side view of the disc, K: _t_ is the rim of the disc, with its holders: _h_ is a portion of the axis of the disc, shown as broken off: _c_ represents a silver band surrounding a pulley, or hub, upon the axis, and directly behind the disc. Upon the hub are metallic ribs, _b_, parallel with its axis, corresponding in number to the letters on the dial. Each rib forms a metallic contact with the silver band, _c_, and are separated from each other by pieces of ivory, fastened to the hub. Both the ribs and ivory pieces are made perfectly smooth and even upon their surface: _e_ is a metallic spring with a portion of it pressing against that portion of the hub between the silver band, _c_, and the disc, _t_, in such a manner that when the disc is turned, the metallic ribs and ivory pieces shall alternately come in contact with it. To this spring is soldered a wire connected with one pole of the battery, _g_, and from the other pole proceeds the wire, _n_: _d_ is another metallic spring, similar to _e_, but pressing _only_ upon the silver band, with which it is always in contact, and to which a wire, _p_, is soldered. Whenever the spring, _e_, is in contact with any of the metallic ribs, there is a continuous connection from _n_ to _p_, viz. from _p_, to the spring in contact with the silver band, _c_, thence to the rib with which the spring, _e_, is in contact; then to the spring, _e_, then to the battery, _g_, and then to the wire, _n_. If, however, the disc, O, should be turned, so that the spring, _e_, is in contact with the ivory, then the circuit is broken at that point, and in this manner the circuit is alternately broken and closed as the wheel, O, is turned from one letter to another by means of the handles at _t_.

Figure 80 represents a side elevation of the dial and clock work of the _receiving station_. A represents an edge view of the electro magnet, from which proceed the two wires, _v_ and _i_, which connect with the wires, _n_ and _p_, of figure 79. J and J is the brass frame containing the wheel work, C and E; the pin wheel, D; the dial plate, I; and the barrel, B, which is driven by a weight and cord. In the side of the wheel, D, are pins projecting from the rim, parallel with the axis, and are equal in number to the divisions, or letters, upon the dial, I. They are, however, placed alternately on each side of the rim. F is the armature of the magnet, fastened upon a horizontal rod, sliding freely through the standards, 1 and 2. G represents a spring, fastened to the frame, J, and which carries back the armature, F, when the magnet has ceased to attract it. From the armature there extends downward an arm, K, which, as it approaches the pin wheel, D, presents two arms, or pallets, one on each side of the wheel. These pallets are so arranged with regard to the pins, that if one pallet releases a pin on one side of the wheel, the same movement will cause the other pallet on the other side, to arrest the motion of the wheel by its striking against the next alternate pin. H and I is an edge view of the circular dial, enclosed in a case, with a single opening at O, so that only one letter at a time can be seen. This dial, I, is in every respect marked as the disc in figure 79.

Figure 81 represents the two instruments. O the _transmitting_ instrument, and the right hand figure the _receiving_ instrument. The wires, _v_ and _i_, are respectively connected with _p_ and _n_. It will be observed, that the armature, F, is not attracted, and that the right hand pallet is checking the pin wheel, so that the dial is stationary. If, however, the disc, _t_, is turned so that the circuit is completed, by the contact of the spring, _e_, with one of the ribs, instantly the armature is attracted by the electro magnet, which will carry the right hand pallet away from the pin wheel, and which will then move by the action of the weight upon the barrel, B, until it is checked by the left hand pallet, which had advanced to the wheel at the same time the other receded. This single operation has moved the disc one division and the armature is still attracted. Now let the disc, _o_, be turned until the spring, _e_, has been passed by the rib, and is in contact with the ivory only, instantly the current ceases; the armature, F, recedes from the magnet by the action of the spring, G; this has taken the left hand pallet from the pin wheel, which is permitted to move until the next pin strikes against the right hand pallet. This has now brought another letter in front of the aperture at H. Thus it will be seen, that the design of this instrument is to bring into view, at the aperture such letters as are required in transmitting a message.

Suppose letter A, is at the point, _b_, of the _disc_; and letter A of the _dial_ is opposite the opening; the instrument is now ready to transmit, and let the letter, I, be the first of the message. The operator gently turns the disc round in the direction of the arrow, so that each time the circuit is broken a new letter appears at the dial, and each time it is closed by the operation of the pallets, in checking and releasing the pin wheel. This is its operation until the letter, I, has reached the point, _b_, when a short pause is made. The next letter, H, requires but one movement of the disc, then follows, A; then, V; and then, E.

In relation to this instrument, Professor Daniell says: “We can only further briefly allude to two of the most important modifications of this invention, which Prof. Wheatstone has made for specific purposes. By substituting for the paper disc, on the circumference of which the letters are printed, a thin disc of brass, cut from the circumference to the centre, so as to form 24 springs, on the extremities of which, types, or punches, are placed, and adding a mechanism the detent of which, acted on by an electro magnet, causes a hammer to strike the punch against a cylinder, round which are rolled, alternately, several sheets of white paper, and of the blackened paper used in the manifold writing apparatus, he has been enabled to obtain, without presenting any resistance to the type wheel, several distinct printed copies at the same time of the message transmitted.”[39]

[39] Daniell’s Introduction to Chemical Philosophy, page 580, 2d Edition, London, 1843

Mr. Wheatstone has recently so modified his telegraph as to use two needles, or galvanometers, and two extended wires, with the ground as half the circuit for the two wires. He has thus adopted PROF. MORSE’S _plan_ of using the ground as a common conductor for two or more wires. He, however, still requires two wires for _one_ independent line of communication; one station only being able to communicate at a same time. He has no mode of recording his message, but depends upon the watchful eye of the attendant. His code of signals are based upon Schilling’s plan, heretofore described, page 155, and also Gauss and Weber’s, page 156, from whom he seems to have obtained his idea.

The two needles, or galvanometers, stand side by side, one of which is called the _left_ needle and the other the _right_ needle. These two needles are placed directly in front of the person who transmits. There are, also, in front, two handles, one for each hand, with which the operator transmits a message, closing and breaking the circuit of the two wires. His signals are made thus: The upper half of the left hand needle moving to the left twice, gives, _a_; three times, _b_; once to the right and once to the left, _c_; once to the left and once to the right, _d_; and, in like manner, for the other letters of the alphabet, as shown in the table which follows.

Left Hand Needle. Right Hand Needle. ll, A. r, E. | l, H. lr, M. lll, B. rr, F. | ll, I. r, N. rl, C. rrr, G. | lll, K. rr, O. lr, D. | rl, L. rrr, P.

Joint Action of Both Needles. l, l, R. ll, ll, S. lll, lll, T. rl, rl, U. r, r, W. rr, rr, X. rrr, rrr, Y. r, completed. ll, rr, I understand, or yes. rl, rl, I do not understand, or no. rl, rl, 1. lr, lr, 2. r, r, 3. l, l, 4. rl, rl, 5. lr, lr, 6. r, r, 7. l, l, l, l, 8. ll, ll, ll, ll, 9. r, r, r, r, 0.

Mr. Wheatstone does not appear to be aware of all the advantages of this, his latest plan of using two needles and two wires, since some of his signals for the _numerals_, are repetitions of his _letter_ signals, and require four deflections of a single needle, with a pause between the two first deflections, and the two last, and for _some_ other signals he requires as many as three deflections of a signal needle. He has likewise, apparently, for want of simple signals, omitted the letters, J, Q, V, Z. He could with perfect ease, obtain from his two wires and two needles, sixty-four different signals, requiring the time of only two deflections, each, and using but one hand for manipulating four keys, instead of both hands, as in his present plan. The author has demonstrated it by actual experiment.