Chapter IX: Part 9

The direction of the current, when the letter V is to be signalled, is this: pressing down the buttons, 9 and 16, at the Paddington station, the fluid leaves the battery, O, along the wire to the cross bar, P; then to the hammer of the button, 16; then to the spring, 4; then along wire, 4, to the galvanometer, 4, and through it, deflecting the lower half of the needle to the left; then along the extended wire, 4, to the dial, and galvanometer, 4, of the Slough station, deflecting the lower half of that needle to the left; then to wire, 4, leaving the dial, to key, 4; then to the cross bar, L and L; and along the cross bar to key, 1; then to wire, 1; then to galvanometer, 1; and through it, deflecting the lower half of the needle to the right; thence it proceeds along the extended wire, 1, to the Paddington station; entering the dial to the galvanometer, 1, deflecting the lower half of the needle to the right; then along wire, 1, to the key, 1; then to button, 9; then to the cross bar, N, beneath; and then to the negative pole of the battery, O. It will be observed, that the needles of both stations, thus deflected, point to the same letter, V. In Mr. Wheatstone’s arrangement, but one person can transmit at the same time, although he uses six extended wires. One must wait while the other is transmitting.

If a numeral is to be signalled, it is obvious, that but one galvanometer is needed. We will, therefore, suppose that the needle, 1, is vertical.

Let the buttons, 7 and 16, be pressed down, at the Paddington station. The current then leaves the positive pole of the battery, O, to the cross bar, P; then to the key, 4; then along wire, 4, to galvanometer, 4, deflecting the lower half of the needle to the left; from thence to the Slough station to galvanometer, 4, deflecting the lower half of the needle to the left; then to wire, 4; then to key, 4; then to the cross bar, L and L, and along it to key, 6; then to wire, 6, and along the extended wire to the Paddington station, to key, 6; then to the cross bar beneath the button, 7; then to the negative pole of the battery, O. The needles, 4 and 4, of both stations, are simultaneously deflected, so as to point to the figure, 4, on the margin of the dial.

In this manner the circuits required for each letter and numeral may be traced out. Now, suppose the message to be sent from the Paddington station to the Slough station, is this, “WE HAVE MET THE ENEMY AND THEY ARE OURS.” The operator at Paddington presses down the buttons, 11 and 18, for signalizing upon the dial of the Slough station, the letter W. The operator there, who is supposed to be constantly on the watch, observes the two needles pointing at W. He writes it down, or calls it out aloud, to another, who records it, taking, according to a calculation given in a recent account, two seconds at least for each signal. Then the buttons, 10 and 13, are pressed down, and the needles are observed to point at E; and so for the remaining letters of the sentence, U excepted, which has no letter on the dial.

The peculiarity of Mr. Wheatstone’s plan, is, the employment of six wires for one _independent_ line of communication. The use of five galvanometers, with their needles, by the deflection of which, 30 letters and numerals are pointed out. The messages are not recorded by the instrument itself, but it is necessary that a person be constantly observing the successive movements of the needles, and note them down as they point to the signal. This plan was invented in 1837, and as Prof. Wheatstone took out letters-patent in the United States, in 1840, for this arrangement, it is a fair inference, that at that time, this was his simplest and most perfect method.

_Steinheil’s Electric Telegraph._

Description of the magneto electrical telegraph, erected between Munich and Bogenhausen, in 1837, by Dr. Steinheil,[32] Professor of Mathematics and Natural Philosophy at the University of Munich, taken from the Annals of Electricity, Magnetism and Chemistry, conducted by William Sturgeon, London, April, 1839.

[32] Steinheil in the account he gives of his own telegraph, says, “Gauss mentions a communication from Humboldt, according to which Belancourt, in 1798, established a communication between Madrid and Aranjuez, a distance of 26 miles, by means of a wire, through which a Leyden jar used to be discharged, which was intended to be used as a telegraphic signal.”

A, A represents a vertical section, through the centre of the coil of copper wire. C is the interior brass frame, round which the wire is wound. B and B are the sides of the frame; I, I, I, I are four brass tubes, soldered to the interior brass frame, and passing through the centre of the coil to its exterior, with a screw cut in the end of each; D and D are two permanent magnets movable on their axis, _a_ and _b_. These spindles, _a_ and _b_, on each side of the magnets, pass up the hollow of the tubes, and having their ends pointed, enter the centre cavity of the four thumb screws, J, J, J, J, by which they are supported, and delicately adjusted, so as to move easily and freely. L and L are the ends of the wire leaving the coil. H and K are two ink holders, attached to the magnets, which will be explained hereafter.

Figure 64 represents a horizontal section of the coil, and magnets D′ and D′, as above described, together with the other arrangements of the instrument for receiving intelligence. The magnetic bars are so situated in the frame of the multiplier, that the north pole, N′, of the one, is presented to the south pole, S′, of the other. To the ends which are thus presented to each other, but which, owing to the influence they mutually exert, cannot well be brought nearer, there are screwed on two slight brass arms, supporting little cups, H′ and K′. These little cups, which are meant to be filled with printing ink, are provided with extremely fine perforated beaks, that are rounded off in front. When printing ink is put into them, it insinuates itself into the tube of their beaks, owing to capillary attraction; and without running out, forms at their apertures, a projection of a semiglobular shape. These little cups are seen at H′ and K′, and in figure 63 at H and K. The horizontal section shows, also, the position of the magnets in the instrument, with the beaks of the pens near the continuous band, or ribbon of paper, E, which is brought in front of the pens vertically from below, over a small roller, F. The paper is supplied from a large roll on a wooden cylinder, upon which is a cog wheel, and connected with a train of wheels and a vane, to regulate the rate of supply. The paper is drawn along before the pen by being wound upon a cylinder, T, concealed by the paper, and on the same shaft with the barrel, M, upon which is wound a cord supporting a weight, N, below. The shaft is supported in the standards, _o_ and _o_, which are fastened to a plate of brass, P and P, also secured to the platform of the instrument. The barrel revolves in the direction of the arrow upon it.

When the electricity is transmitted through the coil of the indicator, both magnetic bars, D′ and D′, make an effort to turn in a similar direction upon their vertical axis, _a_ and _b_. One of the cups of ink, therefore, advances towards the paper, while the other recedes. To limit this action, two plates, V and V′, are fastened at the opposite ends of the free space, allowed for the play of the bars, and against which the other ends of the bars press. Only the end of one bar can, therefore, start out from within the multiplier at a time, the other being retained in its place. In order to bring the magnetic bars back to their original position, as soon as the deflection is completed, recourse is had to two small movable magnets, a portion of which is seen at N and S, whose distance and position are to be varied till they produce the desired effect. This position must be determined by experiment, inasmuch as it depends upon the intensity of the current called into play.

Having described the instrument, its operation is as follows: At the _transmitting_ station is the pole changer, such as we have described in figures 48, 49 and 50, and the magneto electric machine such as is described in figures 45, 46, and 47, and are properly connected, and in the circuit with the instrument of the _receiving_ station, such as we have just described. For one single circuit, one wire extends from the transmitting to the receiving station, the return half of the circuit is the earth. Thus the current passes from the generator along the extended wire to the receiving station, and to the copper plate, then returns through the ground to the copper plate of the transmitting station, to the pole changer and the magneto electric machine. Thus the circuit is complete.

It is clear, from what has preceded, that when the pole changer is thrown to the left side, (the machine being in operation,) the fluid is made to pass in the direction of the arrows, shown at P and N. Then the N′ pole of the left hand magnet advances with its pen, K′, to the paper, E, and a dot is made, and the S′ pole of the right hand magnet recedes with its pen, H, from the paper, until the other end of the magnet strikes the stop, V′. Now, if the letter to be formed, requires two dots in succession from the same pen, the circuit is broken, and the fixed magnets, N and S, bring back the deflecting magnets, D′ and D′, to their former position, when the pole changer is again thrown to the left, and the magnets are deflected in the same manner as at first. Thus two dots are marked upon the paper, on the right hand line. But, now, let the pole changer be thrown to the right hand side, and the current is reversed. The N′ pole of the left hand magnet, with its pen, K, recedes from the paper until it strikes the stop, V, and the S pole of the right hand magnet, with its pen, H′, advances to the paper and makes its dot upon it on the _left_ hand line. The pole changer is then instantly brought to the middle position, and the magnets resume their natural place, by the assistance of the stationary magnets, N and S. The sign which has been marked upon the paper during this operation is ·· · and represents 9.

The following represents Mr. Steinheil’s telegraphic alphabet:

· ·· · ·· ·· ···· · · · · ·
· · · · · · · ···· · · ·· ··
A B D E F G H CH SCH I K L

··· ·· · · ·· · · · · · ··
··· ·· ·· ·· · · · · ··
M N O P R S T V W Z

··· · ·· ·· · ··· · · · · ··
· · · · ··· · ·· ·· · ··· · ···
1 2 3 4 5 6 7 8 9 0

_Masson’s Electric Telegraph._

“In 1837, M. Masson, Professor of Philosophy at Caen, made trial of an electric telegraph, at the college of that city, for a distance of about 600 metres. He employed, for developing the galvanic current, an electro magnetic apparatus, similar, on the contrary, to that of Mr. Pixii, and made it act on magnetic needles placed at two ends of the circuit. Since that time, however, M. Masson has endeavoured to simplify and gradually improve his apparatus.”[33]

[33] Report of the Academy of Industry, Paris, 1839.

_Davy’s Needle and Lamp Telegraph._

The following extracts from the London Mechanic’s Magazine, vol. 28, page 296 and 327, 1837, is all the description we are able to find in relation to it:

“There is a case, which may serve as a desk to use in writing down the intelligence conveyed; and in this, there is an aperture about sixteen inches long, and three or four wide, facing the eyes, perfectly dark. On this the signals appear as luminous letters, or combinations of letters, with a neatness and rapidity almost magical. The field of view is so confined, that the signals can be easily caught and copied down without the necessity even of turning the head. Attention, in the first instance, is called by three strokes on a little bell; the termination of each word is indicated by a single stroke. There is not the slightest difficulty in decyphering what is intended to be communicated.”

_Extract from page 327._

“In front of the oblong trough, or box, described by your correspondent, a lamp is placed, and that side of the box next the lamp is of ground glass, through which the light is transmitted for the purpose of illuminating the letters. The oblong box is open at the top, but a plate of glass is interposed between the letters and the spectator, through which the latter reads off the letters as they are successively exposed to his view. At the opposite side of the room, a small key board is placed, (similar to that of a piano forte, but smaller,) furnished with twelve keys; eight of these have each three letters of the alphabet on their upper surfaces, marked A, B, C; D, E, F; and so on. By depressing these keys in various ways, the signals or letters are produced at the opposite desk, as previously described, how this is affected is not described by the inventor, as he _intimated_ that the construction of certain parts of the apparatus _must remain_ SECRET. By the side of the key board, there is placed a small galvanic battery, from which proceeds the wire, 25 yards in length, passing round the room. Along this wire the shock is passed, and operates upon that part of the apparatus which discloses the letters or signals. The shock is distributed as follows: The underside of the signal keys are each furnished with a small projecting piece of wire, which, on depressing the keys, is made to enter a small vessel, filled with mercury, placed under the outer ends of the row of keys; a shock is instantly communicated along the wire, and a letter, or signal, is as instantly disclosed in the oblong box. By attentively looking at the effect produced, it appeared as if a dark slide were withdrawn, thereby disclosing the illuminated letter. A slight vibration of the (apparent) slide, occasionally obscuring the letter, indicated a great delicacy of action in this part of the contrivance, and although not distinctly pointed out by the inventor, is to be accounted for in the following manner: when the two ends of the wire of the galvanic apparatus are brought together, over a compass needle, the position of the needle is immediately turned, at right angles, to its former position; and again, if the needle is placed with the north point southward, and the ends of the wire again brought over it, the needle is again forced round to a position at right angles to its original one. Thus, it would appear, that the slide or cover over the letters, is poised similarly to the common needle, and that by the depression of the keys, a shock is given in such a way as to cause a motion from right to left, and _vice versa_, disclosing those letters, immediately, under the needle so operated upon.”

_Alexander’s Electric Telegraph, from the (Scotsmen) Mechanic’s Magazine, Nov. 1837._

“A model to illustrate the nature and powers of this machine was exhibited on Wednesday evening at the Society of Arts in Edinburgh. The model consists of a wooden chest, about five feet long, three feet wide, three feet deep at the one end, and one foot at the other. The width and depth in this model are those which would probably be found suitable in a working machine, but it will be understood that the length in the machine may be a hundred or a thousand miles, and is limited to five feet in the model, merely for convenience. Thirty copper wires extend from end to end of the chest, and are kept apart from each other. At one end (which, for distinction’s sake, we shall call the south end) they are fastened to a horizontal line of wooden keys, precisely similar to those of a piano forte; at the other, or north end, they terminate close to thirty small apertures, equally distributed in six rows of five each, over a screen of three feet square, which forms the end of the chest. Under these apertures on the outside, are painted, in black paint, upon a white ground, the twenty-six letters of the alphabet, with the necessary points, the colon, semicolon, and full point, and an asterisk, to denote the termination of a word. The letters occupy spaces about an inch square. The wooden keys, at the other end, have also the letters of the alphabet, painted on them in the usual order. The wires serve merely for communication, and we shall now describe the apparatus by which they work.

This consists, at the south end, of a pair of plates, zinc and copper, forming a galvanic trough, placed under the keys; and at the north end, of thirty steel magnets, about four inches long, placed close behind the letters painted on the screen. The magnets move horizontally on axes, and are poised within a flat ring of copper wire, formed of the ends of the communicating wires. On their north ends they carry small square bits of black paper, which project in front of the screen, and serve as opercula, or covers, to conceal the letters. When any wire is put in communication with the trough at the south end, the galvanic influence is instantly transmitted to the north end; and in accordance with the well known law, discovered by Oersted, the magnet at the end of that wire instantly turns round to the right or left, bearing with it the operculum of black paper, and unveiling a letter. When the key, A, for instance, is pressed down with the finger at the south end, the wire attached to it is immediately put in communication with the trough; and at the same instant, letter A, at the north end is unveiled, by the magnet turning to the right, and withdrawing the operculum. When the finger is removed from the key, it springs back to its place; the communication with the trough ceases; the magnet resumes its position, and the letter is again covered. Thus by pressing down with the finger, in succession, the keys corresponding to any word or name, we have the letters forming that word, or name, exhibited at the other end; the name VICTORIA, for instance, which was the maiden effort of the telegraph on Wednesday evening.”

The above description is all that we have been able to obtain in relation to this plan of an electric telegraph and here introduce, figure 65, to illustrate it. The 30 needles are represented on the screen, each carrying a shade, which conceals the letter when the needle is vertical. The needle belonging to the letter F, is, however, deflected, and the letter is exposed. The screen is supposed to be at the _receiving_ station. To the left hand of the screen, 30 wires, _e, e_, are seen joined to one, _a_; the other 30 wires, _d, d_, are seen below the screen. These wires may be supposed to extend many miles, and to be joined with their corresponding wires, _c_, and also _v, v_, of the _transmitting_ station, where it will be observed, the wire, _c_, connects with the battery at one pole, and from the other pole a wire is continued and soldered to the metallic plate, _o, o_, which extend under all the 30 keys, _i, i_. These keys are each insulated, at their extremity, by being fastened to a wooden standard, L, L, to which a wire is soldered. Now, suppose the key, F, is pressed down, (the sixth key from the left,) the fluid then passes from the battery, B, through the wire to _o_, the plate; then to the key in contact with it; then to its wire, marked by the arrow; thence through the extended wire to its corresponding wire at the receiving station, denoted by the arrow; then through the coils of the multiplier, deflecting the needle, F; then returns through its wire, at the left, to the common wire, _a_; then through the extended wire to C, and the battery, of the transmitting station. In this manner any letter upon the screen may be indicated.

_Extract from the Report of the Academy of Industry, in reference to a suggestion of M. Amyot of an Electric Telegraph._

“M. Amyot announced, in a letter addressed to the Academy of Sciences, in April, 1838, that he also proposed to construct an electric telegraph. It was to consist of a single current, which would move a single needle, which needle would of itself write on paper, with mathematical precision, the correspondence which might be transmitted to the other extremity, by a simple wheel on which it should be written by means of points, differently spaced, the same as they are on the barrels of portable organs. In order to send any news then, he required to write, by means of movable characters, which must be constructed in a certain manner, and immediately it would be repeated and transcribed at the place where he wished to address it, on paper, which could be put into the hands of persons specially employed to transmit despatches. But all that method of execution, which it seems ought to move is clock work, not having been sufficiently described by the author, the _most vague uncertainty_ yet reigns as to the true construction of that apparatus, which appears to us to have been for M. Amyot, rather the occasion, than the end, of this communication; for indeed he attempted to make the possibility admitted of establishing a universal telegraphic language of his invention.”

_Edward Davy’s Electric Telegraph._[34]

The following description of Mr. Davy’s telegraph is taken from his specification and drawings, published in the Repertory of Patent Inventions. Although the specification has given the basis of his plan, yet the description contained therein, and the drawings representing his plan, are so obscure and deficient, that to have given it to the public in that form, would have represented it as perfectly impracticable. He has failed to state the number of signals which it is capable of giving. He has committed great errors in the arrangement of his wires for producing signals. He has introduced two keys, which produce the same signals as two others in the same arrangement. He has employed three extended wires for communicating from one station to another station, and by his arrangement of them, could not have obtained more than four signals. He has also very obscurely described his escapement, by which his marking cylinder is made to advance one division at a time for receiving the signals. This latter difficulty, however, we have been enabled to clear up, by a description of it in a work published by Mr. Bain. Notwithstanding the imperfections and obscurities of his specification and drawings, we have endeavoured to carry out his plan, and give it a practical shape, perhaps, as Mr. Davy originally designed it.

[34] From the Repertory of Patent Inventions, No. lxvii. New Series, London, July, 1839.—Sealed, July 4th, 1888.

As it is now described, there are 26 signals, or marks, indicating letters. The employment of four wires instead of three, or if Mr. Davy chooses to use for the common communicating wire the ground, which is perfectly practicable, it will reduce the number to three, the number he has specified. We have introduced one key more, and so arranged the two superfluous keys as to make them available. With this preliminary, we will proceed with the description.

Figure 66 represents a top view of the arrangement of the wires, mercury cups, and batteries of the _transmitting station_. The close parallel lines represent the wires, of which D, A, B and C are those which proceed to the receiving station. 1′, 2′ and 3′ are the three batteries, of which, P and N are their respective poles. The small circles formed at the termination of the wires, and marked 7, 1, 10, 2, 20, &c. are mercury cups, in which the terminating wires are immersed. The wires 1 and 20, and 2 and 10, &c. which cross each other, are not in contact, but perfectly insulated. The wires shown in this figure, are all secured permanently, with their mercury cups, to one common base board. The letters H, J, K, M, O and U represent the places of the six finger keys, used in transmitting signals. There is, also, another key at 7, for uniting the wire, D and D. In this figure, however, the keys themselves are omitted, in order to render more clear the arrangement of wires under and around them. Another figure, 67, is here introduced to illustrate the plan of one set of wires and their two keys. In figure 67 is represented, in a top view, the two wooden keys, A and B, and their axes, at E and F. G is the battery, of which, 9 is the positive pole, and 10 the negative pole. The small circles, marked 1, 2, 3, 4, 5, 6, 7 and 8 represent the mercury cups. C and C′, and also, D, are the extended wires. The keys, A and B, have each two wires, passing at right angles through the wooden lever. The wires of the key, A, are marked 1 and 2, and 5 and 6, and those of the key, B, are marked 3 and 4, and 7 and 8. These wires, directly over the mercury cups, are bent down a convenient length, so as to become immersed in the cups, when the lever is depressed, and rise out of them, when the lever is elevated. Now, if the key, A, is depressed, the cup, 1, is brought in connection with cup 2; and 5 is connected with 6, by the wires, supported by the lever, being immersed in the mercury; and the key, B, not being depressed, there is no connection of the cup 3 with 4; or 7 with 8. At X and X, under the lever, are springs, which keep the lever elevated; and, consequently, the wires out of the cups, when the keys are not pressed down.

Figure 68 represents a side view of the lever, or key, A, and its axis at E. R is the platform supporting the standard of the axis; the stationary wires; the battery, G; and the mercury cups, _a, a_ and 10. X is the spiral spring, for the purpose of carrying back the lever, after the finger is taken off and sustaining it in its elevated position. Through the centre of the spiral, passes a rod, with a head upon it at the top of the lever, to limit its upward motion. At its lower end, the rod is secured in the platform, R. 4 and 8 are the two wires supported by the lever, A, and are seen to project down directly over the mercury cups, _a_ and _a_, so that by depressing the key, they both enter the cups and form a metallic connection. The key, B, figure 67, has the same fixtures and is similarly arranged as the key, A, represented above.

Figure 69 represents a top view of die arrangement of multipliers at the _receiving_ station. R′, R′ and R′; R, R, and R are six magnetic needles, or bars, each of which move freely upon a vertical axis passing through their centres. The lower point of their axes is immersed in cups of mercury, in which also terminate the wires, I, I, I and L, L, L. The wires, D″, A′, B′ and C′, are those coming from the _transmitting_ station. A′, B′ and C′, each enter the needle arrangement, and first passing from left to right, over the magnetic bars, R′, R′ and R′, in the direction of their length, then down and under and round, making many turns, leave these three needles and pass _under_ the needles, R, R and R, and in like manner from right to left round them, making a number of turns, then pass off and unite together, in the wire, 9, which is a continuation of D″. This wire is called the _common communicating wire_,[35] and the wires, A′, B′ and C′ are called _signal wires_. At right angles, there projects from each magnetic bar, a metallic tapered arm, which rests against the studs, V, V, V, V, V, V, when the needle is undisturbed. But when the needles are made to move in the direction, to carry the arms to the left, they are brought in contact with the metallic stops, S, S, S and T, T, T. To each of these stops, it will be observed, a wire is soldered, and continued respectively from S, S, S to ̈1, ̈3, ̈5, and from T, T, T to ̈2, ̈4, ̈6. It will also be observed, that from each of the mercury cups below the magnetic bars, the wires, I and L, and I and L, and I and L, proceed and unite in pairs at, L, L, L; these three united wires are then continued, and the whole are joined in one at 8. The wires, ̈1, ̈2, ̈3, ̈4, ̈5, ̈6, are continued, in a manner hereafter to be described, and are connected with one pole of a battery. The wire, 8, is also continued and connected with the other pole. So that if any one of the needles should be made to move its arm to the left, thereby coming in contact with its metallic stop, the circuit would be complete and the current would pass along the wire, ̈1, for example, to the metallic stop, then to the arm, and to the magnetic bar; then to the axis; then to the mercury; then to the wire, I, and thence to the wire, 8. In the same manner the current would pass if any other arm was brought against _its_ metallic stop. All the wires represented in this figure are permanently secured in their places upon a common platform.

[35] A′, B′ and C′ are also, occasionally, common communicating wires.

In order to understand the combined operation of the keys and needles, figure 70 is here introduced. The right hand figure, is the same as figure 69, and the left hand the same as figure 66.

_Transmitting Part of Receiving_ _Station. Station._]

The wires, D″, A′, B′ and C′, are detached from their corresponding wires of the transmitting station, and it may be imagined that many miles of wire intervene and connect the two. In the left hand figure, those mercury cups above and below, 1 and 10, are joined by two wires passing through a moving lever, in the same manner as has been described in figure 67. We will, therefore, call the key, carrying these two connecting wires, H. In like manner the key for the cups above and below the numbers, 2 and 20, is called J; for 3 and 30, is K; for 4 and 40, is M; for 5 and 50 is O; for 6 and 60, is U. The key which connects the two mercury cups on the right and left of number 7, of the wire, D″, is called 7. There are 7 keys; two for each battery, 1′, 2′ and 3′, and each wire, A′, B′ and C′; and one for the common wire, D″.

It will now appear, that if the key, U and 7, are depressed, the cups above and below, numbers 6 and 60; and the cups on each side of number 7, will be connected together so that the current leaving, P, or the positive pole of the battery, 3′, goes to the lower cup, 50; then by the stationary cross wire to upper cup, 6; then passes to lower cup, 6, by the wire supported by the lever, U, which is now pressed down, and its ends immersed in the two cups; then along the wire, D, to the left hand cup, 7; then to the right hand cup, 7, by the wire supported by the lever, 7, and which is immersed in the two cups; then through the extended wire to D″, of the _receiving_ station; then through 9, to the two multiplying coils of the wire, C′, deflecting the arm of the needle, R, to the right, against the stop, V; and the arm of the needle, R′, to the left against the metallic stop, S, as indicated by the arrow at S; then along the extended wire, back to the lower cup, 60, of the _transmitting_ station; then to upper cup, 60, through the wire supported by the lever, U; then to N, the negative pole of the battery, 3′.

It will be observed of the two needles, R and R′, in the circuit of the same wire, C′, that if R is deflected to the right against the stop, V, then R′ will be deflected to the left against the metallic stop, S. The current, to produce these deflections, being through the wire C′, in the contrary direction to that indicated by the arrow of the wire, C′. But if R is deflected to the left against the metallic stop, T, then R′ will be deflected to the right against the stop, V. The current to produce these deflections, will then be through the wire, C′, in the direction of the arrow of that wire. The same effect is produced upon the two other pairs of needles of the wires, A′ and also B′. These contrary movements of the two needles, when a _current_ is passing, are produced by the coils being so wound, (see figure 69,) that the wire passes round one needle in a contrary direction to what it does round the other.

If, now, we depress the keys, O and 7, the cups above and below, 5 and 50, and on each side of number 7, will be connected. The fluid will then pass from P or positive pole of the battery, 3′, to the lower cup, 50; then through the key wire to upper cup, 50; then along the extended wire, C′ to the _receiving_ station; then through the coils of the multipliers, deflecting the arm of the needle, R, to the left against the metallic stop, T; and the arm of the needle, R′, to the right against the stop, V, as indicated by the arrow at V; then to wire, 9 and D″; then along the extended wire back to the _transmitting_ station, to the right hand cup, 7; then by the key wire to the left hand cup, 7; then to wire, D; then to upper cup, 5; and through the key wire to lower cup, 5; then by the cross wire to upper cup, 60, and then to N, or negative pole of the battery.

We have now shown the route of the current, when the keys, U and 7; and the keys, O and 7, were depressed. It will be observed, that when the keys, U and 7 were used, the current through the wire, D″, was from _left_ to _right_; and when the keys, O and 7, were used, the current was from _right_ to _left_. Thus, by means of the six keys, the current of each battery may be made to pass in either direction through the _common communicating_ wire, D″. By the keys, U, M, J, with 7, the current is made to pass from _left_ to _right_ along the wire, D″. By the keys, O, K, H, with 7, the current is made to pass from _right_ to _left_ along the wire, D″. By these six keys, all those various deflections of the six needles are produced, which are necessary to close the circuit of such of the wires, ̈1, ̈2, ̈3, ̈4, ̈5, ̈6, with the wire, 8, as are required for marking the signals desired, on an instrument now to be described.

Figure 71 represents a top view of that part of the instrument at the _receiving_ station, by which the signals are recorded. The seven wires on the left of the figure are a continuation of those wires, marked ̈1, ̈2, ̈3, ̈4, ̈5, ̈6, and 8, in figure 70. The first six pass through a wooden support, _b_ and _b_, and terminate upon the edge of the platinum rings, _a_, _a_, _a_, _a_, _a_ and _a_, forming a metallic contact. The six platinum rings surround a wooden insulating cylinder, _t_, which revolves upon axes in the standards, _h_ and _i_. The rings are _broad_ where they come in contact with the wooden roller, and are bevelled to an _edge_ where they come in contact with the six wires. Y represents a compound battery, with one pole of which, wire 8, from the needle arrangement, figure 70, is connected, and from the other pole the wire proceeds to the electro magnet, Z, Z; it then passes on and is brought in connection with the metallic cylinder, _d_, at the point, _g_. The cylinder, _d_, revolves upon axes, and is supported in the standards, _k_ and _l_. To the cylinder is attached a barrel, _n_, upon which is wound a cord, supporting the weight, _e_, by which the cylinder is made to revolve. C′, C′, represents a prepared fabric, such as calico, (impregnated with hydriodate of potass and muriate of lime,) and is placed between the platinum rings, _a, a, a, a, a, a_, and the metallic cylinder, _d_; _o_ is a cog wheel upon the end of the axis of the cylinder, _d_, and is connected with other machinery, omitted here, but shown in figure 72, which is a side elevation of part of figure 71: _o_ is the cog wheel, (figure 72,) on the arbor of the cylinder, _d_. B and B, are the two sides of the frame containing the clock work, and is secured to the platform, R: _d_ is a part only of the metallic cylinder, upon which is seen a portion of the prepared fabric, K. The cog wheel, _o_, drives the pinion, A, on the shaft of the fly vane, G. M is an end view of the electro magnet, (represented by Z, Z, in figure 71,) of which N and P are the two ends of the wire composing the helix. D is its armature, constructed so as to move upon an axis represented by two small circles. To the armature are connected, and capable of moving with it, two arms, E and I, which project, so as to come in contact with the pallet, _a_, of the fly, G. F is a spiral spring, one end of which is fastened to the armature, D, and the other passes through a vertical hole in the screw, S, in the bar, T, by which the armature is held up in the position now seen, when not attracted by the electro magnet. Now, if the wires, N and P, connected with battery, Y, (figure 71,) have their circuit closed, the current passing through the helix of the magnet, M, brings down the armature, D, in the direction of the arrow, which raises the arm, I, against which the pallet, _a_, of the fly vane, is resting, and releases the fly. It then makes a half revolution and is again arrested by the pallet against the lower arm, E, and the cylinder, _d_, with its fabric, has advanced a half division. If the circuit is now broken, the armature, D, is carried up by the spring, F, at the same time the arm, E, releases the pallet, _a_, and the fly makes another half revolution, and is again stopped by the arm, I. The cylinder has now made another advance of half a division, which, together, makes a whole division the fabric has advanced. The purposes for which this is designed will now be described.

Figure 73 represents a top view of the whole apparatus of the _receiving_ station. The fabric, C′, C′, is marked in equal divisions across it, and in six equal divisions, in the directions of its length, thus marking it into squares. Each platinum ring, _a, a, a_, &c. (when the instrument is not in operation,) is in contact with the fabric at the _middle_ of the squares across the fabric. It will be observed, that the wires ̈1, ̈2, ̈3, ̈4, ̈5, ̈6 are in connection with the battery, Y, and the circuit complete, except at the arms of the needles. Suppose, for example, the arm of the needle, R′, of the wire, C′, is brought up against the stop of the wire, ̈5, at S; the circuit is then closed, and the current leaves the battery, and passes to the electro magnet, (causing the cylinder and fabric to move half a division,) then to the metallic cylinder, _d_; then through the fabric, _c′, c′_, resting upon the cylinder, (where it is in contact with the platinum ring, _a_, of the wire, ̈5,) then to the platinum ring; then to wire ̈5; then to the metallic stop, S; then to the arm of the needle, R′, along its axis to the mercury; then to the wire, I; then to wire, 8, and to the other pole of the battery, Y. Thus a current is passed through the prepared fabric, and a mark produced thereon, in the middle of its square. If the circuit is now broken, the cylinder moves another half division, which will bring the rings to the centre of the squares, ready for the next signal.

But one battery, Y, is used for all the six circuits, formed with the wire, 8; so that, when three of the circuits are closed at the same instant, as will be shown hereafter, the current passes through the three wires of their respective circuits, making each their appropriate mark upon the fabric.

We now proceed to describe the manner of operating with the two instruments, at their respective stations: and, first, we must here designate each needle by its own peculiar mark of reference. Let the two needles upon the wire, A′, be denoted by, A, S and A, T; those of the wire, B′, by B, S and B, T; and those of the wire, C′, by C, S and C, T. It will appear obvious, from the foregoing description, that but _one_ needle of each _wire_, A′, B′, C′, can be made to close its circuit at the same instant. However, _two_ needles, or _three_ needles of _different wires_, may close their circuits at the same instant, but no higher number than three. The various combinations of _one_ mark, _two_ marks, and _three_ marks, upon the same row of six cross divisions of the fabric, constitute the characters representing letters.

LONDON.—_Transmitting Station._]

Figure 74 represents the _transmitting_ station, which may be supposed to be _London_, and figure 75, the _receiving_ station, which may be at _Birmingham_, with four wires extending from station to station, or three only, if the _ground_ be substituted for the wire, D, D″. The wires, D, A, B and C, are supposed to be united with D″, A′, B′ and C′, respectively. Now, if we depress the keys, in the following order, we shall, for each key, have the following deflections of the two needles, belonging to each key.

No. 1.
The keys, H, 7, moves the arm, A, S, to the right, A, T, to the left.
“ J, 7, “ A, S, “ left, A, T, “ right.
“ K, 7, “ B, S, “ right, B, T, “ left.
“ M, 7, “ B, S, “ left, B, T, “ right.
“ O, 7, “ C, S, “ right, C, T, “ left.
“ U, 7, “ C, S, “ left, C, T, “ right.

These are all the various deflections which it is possible to give the six needles. Those, however, which deflect to the right, not closing the circuit, produce no effect, and are of no account. We will, therefore, omit them, and simply give the table, thus:

No. 2.
The keys, H, 7, move the arm A, T, to the left. No. 1.
“ J, 7, “ A, S, “ “ 2.
“ K, 7, “ B, T, “ “ 3.
“ M, 7, “ B, S, “ “ 4.
“ O, 7, “ C, T, “ “ 5.
“ U, 7, “ C, S, “ “ 6.

BIRMINGHAM.—_Receiving Station._]

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.