Part 19

Figure 59 represents a side view of the key arrangement. F is the platform. E the wooden support of the six keys. H is the larger spring, or key, secured to the support by screws, _h_. The spring is observed to project beyond the metallic cross bar, L, after passing beneath it. R is the support of the cross bar, L. N and O are two of the ivory buttons, upon their spiral springs, _a_ and _c_. Below the button, O, is a shoulder, formed at _i_, upon the stem which passes through the spring, H, and another shoulder is formed by the hammer, _u_, below the spring. It will be observed, that two buttons of the same key are never used at the same time. If the button, O, is to be pressed down, the weaker spring, _c_, will permit it to descend until the upper shoulder comes in contact with the larger spring, H, when more pressure is applied, and that spring is brought down, breaking its contact with the metallic cross bar, L, until the hammer, _u_, comes in contact with the metallic plate, _n_, upon the support, K, and as the plate, _n_, is connected with N pole of the battery, the connection is formed with it. It will, however, be noticed, that the button, N, not being pressed upon, _will not_, (though it descends with the larger spring,) be brought in contact with the other plate upon the support, J, and connected with the positive pole of the battery. To the end of each spring, a wire, S, is soldered, the purpose of which will be shown hereafter.

Figure 60 represents an end view of the key arrangement; _a_, _b_, _c_, _d_, _e_, _f_, are the buttons, M and M the metallic cross bar, beneath which are seen the ends of the six larger springs, 6, 1, 2, 3, 4 and 5. R and R are the supports of the bar, M and M. G is the platform. W is the support of the metallic plates, with which the hammers of the little keys, or buttons, come in contact. S the wire leading to the battery.

Having shown the several parts of Mr. Wheatstone’s plan, we will proceed to describe the arrangement of two termini, as prepared for transmitting intelligence. Figure 61 represents the arrangement of one station, which we may suppose to be PADDINGTON. Figure 62 represents the plan of the other station, which we will suppose to be SLOUGH. The distance between these two places is eighteen miles.

In figure 61, it will be seen, that a wire is soldered to the end of each of the springs 6, 1, 2, 3, 4 and 5, and are respectively connected with the five wires of the dial, and the common communicating wire, number 6, which does not pass through the dial, nor is connected with any of the galvanometers. On the right hand side of the dial, the wires are extended until they are shown as broken. From this point to the opposite one, figure 62, where the wires appear also as interrupted, we may suppose 18 miles to intervene. The wires here proceed to the dial of the Slough station, making their proper connections with their respective galvanometers, and from thence are continued and soldered to their springs of the key arrangement, with the exception of wire, number 6, which passes direct to the key, 6, without going through the dial case. In both figures, is represented the battery, O, consisting of six cups. The wire from one pole of the battery is connected with the N metallic plate, the other wire with the P metallic plate. While none of the buttons are pressed down, the battery is _not_ in action, and it will also be observed that the circuits are all _complete_. The action of the keys, then, is this, by a single operation to break the circuit formed with the cross bar, L, L, and, at the same time, bring _into_ the circuit, the battery, O.

The following numbers, representing the buttons, are those necessary to be pressed down, in order to signal the letters and numerals on the dial:

_Letters._ For A, buttons 10 and 17. | For M, buttons 9 and 12. “ B, “ 10 “ 15. | “ N, “ 11 “ 14. “ D, “ 12 “ 17. | “ O, “ 13 “ 16. “ E, “ 10 “ 13. | “ P, “ 15 “ 18. “ F, “ 12 “ 15. | “ R, “ 9 “ 14. “ G, “ 14 “ 17. | “ S, “ 11 “ 16. “ H, “ 10 “ 11. | “ T, “ 13 “ 18. “ I, “ 12 “ 13. | “ V, “ 9 “ 16. “ K, “ 14 “ 15. | “ W, “ 11 “ 18. “ L, “ 16 “ 17. | “ Y, “ 9 “ 18.

_Numerals._ For 1, buttons 7 and 10. | For 6, buttons 8 and 9. “ 2, “ 7 “ 12. | “ 7, “ 8 “ 11. “ 3, “ 7 “ 14. | “ 8, “ 8 “ 13. “ 4, “ 7 “ 16. | “ 9, “ 8 “ 15. “ 5, “ 7 “ 18. | “ 0, “ 8 “ 17.

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.”