Part 16

Mr. Saxton, however, was still further successful, the following year, in carrying out an idea which occurred to him on the 6th of December, 1832, of producing the same phenomena, with a more convenient and powerful rotating instrument.[26] This new arrangement he was able to test on the 20th of June, 1833, and obtained the spark. On the 22d, he made an unsuccessful attempt, in the presence of Prof. Rogers, of Philadelphia, at the decomposition of water. On the 30th of June he exhibited it at a meeting of the British Association at Cambridge, before Dr. Faraday, Dr. Brewster, Prof. Forbes, Dr. Dalton, and many other distinguished and scientific gentlemen. The experiments made by it were the exhibition of the spark, giving shocks, &c. On the third of July, Mr. Saxton succeeded in decomposing water, by adding a little sulphuric acid, and on the 25th of August, he ignited and melted platinum wire.

[26] In relation to this instrument, Prof. Daniell makes the following remarks: “After Dr. Faraday’s discovery of _Volta electric_ and _magneto electric_ induction, many ingenious contrivances were made for exalting the effects and facilitating experiments. The most complete arrangement now in use, was the original combination of Mr. Saxton.”

Figure 43 exhibits a side view of the instrument: _a_, _a_, _a_, is a compound permanent magnet, consisting of three steel plates, put together, side by side. B and C are two wooden supports, upon the platform A A. To these supports the magnet is permanently secured, by a yoke, S, through which pass two screws into the wooden supports below. M is a cross bar, into which, and at right angles with it, are screwed two arms of round soft iron, R, about five-eighths of an inch in diameter, the whole forming the armature or keeper of the magnet. Upon these two projecting arms, are placed two coils, D′ and D, of copper wire, insulated with silk. The whole is very securely fastened upon the steel spindle, N, which has its journals in the supports, B and B′. On the end of the spindle, N, near the curve of the magnet, there is a small band pulley, F, which is driven by the band or cord of the large wheel, E, and the crank, J. The axis of the large wheel passes through a long socket, L, in the top of the column, H; on one end of the axis the band wheel is fastened and on the other the crank. By this arrangement a very rapid and quiet rotary motion is given to the armature.

In the column, H, there is a socket, into which the stem of the upper part of the column, G, is fitted, which admits of the large wheel being raised or lowered, so as to prevent the band from slipping, and when properly adjusted it is secured by the screw, I. O is an ivory hub, sliding over that part of the spindle immediately projecting beyond the cross bar, M. Upon this ivory hub is a copper disc, C, with a socket, _n_: _b_, is a needle made of platinum, which, with its socket, _m_, is nicely fitted upon the end of the steel spindle, so as to be adjusted to any required angle with the armature, and when adjusted to retain its position. The two ends of the two coils, which leave the _centre_ of the helices, are made to form a contact with the soft iron arms, R R, passing through the coils, D′ and D, thus making the circuit complete with the needle _b_, upon the end of the spindle, N, by a continuous metallic connection of the arms, with the cross bar, M, and through the cross bar to the spindle, N, in contact with the needle, _b_. The two ends of the two coils, leaving the _outside_ of the helices, are joined in one, and as they pass through the cross bar, M, are insulated from it, by a piece of ivory, inserted in the cross bar. The united wire then passes into and through the ivory hub, _e_, forming a perfect contact with the copper disc, _c_, underneath its socket, _n_: _d_, is a cup of mercury, in which the copper disc, _c_, is always immersed, and the needle, _b_, twice in every revolution of the armature. The cup, _d_, is so constructed as to rise and fall, by means of a stem, _i_, sliding vertically into a socket, _e_, of its support, and is secured to its position by the screw, _h_. In this way, its proper height for breaking and closing the circuit may be easily obtained, when the armature is rotating. The proper position for the needle, _b_, is that in which it is just leaving the mercury, as the keeper arrives at the position, in which its magnetism is neutralized. This position is seen at X, where D″ and D′ are the sides of the coils; _c_ the copper disc; _m_ the cross bar of the armature; R the arm passing through the coil; and _b_ the needle, at that _angle_ which it requires, when the armature is vertical or at its neutral position. It will be observed that the needle is just leaving the mercury, _d_.

Figure 44 represents a top view. N and S represent the north and south poles of the permanent magnet. N′ and N′ is the spindle, parallel with the prongs of the magnet, and equidistant from them; L is the socket of the band wheel; D′ and D the horizontal position of the coils; M is the cross bar; _b_ the needle; _c_ the copper disc, and _m_ and _n_ their respective sockets; _o_ the ivory hub; _d_ the cup of mercury; A the platform; and S′ and S′ the yoke through which pass two screws to secure the magnet to the wooden support below.

When the armature is made to rotate, it becomes a temporary magnet, by the laws of magnetic induction, whenever the arms carrying the helices come opposite to the poles of the permanent magnet, and when these soft iron arms have reached the point at _right angles_ to the _magnet_, or vertical, their magnetism for an instant is destroyed, and are as instantaneously reversed from what they were before reaching that point. They are also magnetic, just in that proportion as they recede from or approach to the poles of the permanent magnet.

Hence, first, _one arm_ is the south pole, when opposed to the north pole of the magnet; and the _other arm_ a north pole, when opposed to the south pole of the magnet. But when they have made a half revolution on their axis, from their first position, their magnetism is reversed. The arm which was a south pole, has become a north pole; and the arm that was a north pole has become a south pole. Thus, by the rotation of the armature, direction of the induced current in the arms, become changed, as often as they are alternately brought opposite the poles of the permanent magnet, which is _twice_ in every revolution of the armature.

It follows, then, by the laws of magneto induction, that as often as the arms become magnetic, they induce corresponding _opposite electric_ currents in the wire surrounding those arms, provided the circuit of the coils is complete. The disc, which is in metallic connection with two ends of the wire leaving the coils, (one from each coil,) is _always_ immersed in the mercury of the cup. The needle, however, which is in connection with the other two wires from the two coils, (one from each coil,) is _not always_ immersed, but only when the armature is at a certain position in relation to the permanent magnet. The circuit then can only be closed when the needle is immersed, as well as the disc. Upon inspecting the figure, it will be found that the needle is immersed at the time the arms are passing the poles of the magnet, and that when they arrive at the vertical or neutral position, the needle has just broken its connection with the mercury, and at that instant the spark is observed.

Professor Daniell observes, that “by means of this magneto electrical machine, all the well known effects of Voltaic currents may be very commodiously produced. When the communication is made between the spindle and the revolving disc, by means of a fine platinum wire, instead of the dipping points, the wire may be maintained at a red heat; although the effect being produced by alternating currents in opposite directions, a kind of pulsation, or intermission of the light, may be discerned. Upon making the communication between the two mercury cups, by means of copper cylinders _grasped_ in the _hands_, a continued painful contraction of the muscles of the arm takes place, which destroys voluntary motion, and, under certain circumstances, is perfectly _intolerable_.

“The general expression of these phenomena may be thus stated: whenever a piece of metal is passed, either before a single pole, or between the opposite poles of a magnet, or before electro magnetic poles, whether ferruginous or not, so as to cut the magnetic curves, (or lines, which would be marked out by a spontaneous arrangement of iron filings,) electrical currents are produced across the metal, transverse to the direction of motion.”

_Dr. Page’s Magneto Electric Machine._

This important instrument also depends, for its action, upon the principle discovered by Dr. Faraday, that electricity was developed in conducting bodies, when they were moved in a certain direction, in the neighbourhood of permanent magnets. Since the beautiful and ingenious invention which Mr. Saxton was the first to make, no valuable improvements have been made in this machine, except those introduced by Professor Page.

The first important change in the machine, was the adaptation of his pole changer to the machine, in place of the break pieces, which were used in all the modifications up to that time; and another equally useful improvement, consisted in the arrangement of the permanent magnets and armatures. Previous to this last improvement, these machines were constructed with a single permanent magnet, and one or more revolving armatures, necessarily involving great disadvantages. Page’s improvements were completed in February, 1838, and shortly after published in Silliman’s Journal. He was also the first to suggest the combination of several machines under one mechanical movement, as the best mode of augmenting power in this way.

_The combined machine, described in Daniell’s Introduction to Chemical Philosophy, as invented by Wheatstone, about two years since, is the same as that described, and represented by Dr. Page in Silliman’s Journal in 1838._ In the same publication, Dr. Page described the arrangement of the permanent magnets and armatures, as shown in the annexed figures. The adaptation of the pole changer, which, in connection with this machine, is called the _Unitrep_, Dr. Page has given to the public. But as he has never allowed the improvement, which consists in the use of two or more permanent magnets and straight armatures, to be sold with his knowledge and consent, he intends to claim a _patent for the same_; it having been decided by our courts, that the publication of an invention by the inventor, does not affect his right to a patent, provided he does not allow the invention to be sold and used.

The figures 45, 46 and 47, exhibit one of Page’s machines with his early improvements.

Figure 45, is a side elevation of the machine.

Figure 46, is a top view.

Figure 47, are views of the revolving armatures and coils.

In Figure 45, representing a side view of the machine, B and B are the compound permanent steel magnets, composed of six bars each of the U form, mounted upon the brass pillars, P, P, P, P, which are fastened into the common platform of the whole machine. Through the platform there pass stout rods, R and R, and upwards through two brass straps, above the magnets, B and B. These straps or yokes secure the magnets from any motion by means of the screw nuts. A is a circular case of pasteboard, containing the armatures and coils. H is a band wheel surrounding the case, for mechanical connection with any source of power that may be used to keep the machine in motion. I′ and I are two metallic studs, with an aperture passing vertically from the top, to the depth of an inch, for the reception of connecting wires, and then, by means of a screw at its side, to make a perfect contact. There are two other studs directly behind them. G and J are the two pulley wheels, with their band and crank, by which a rapid rotary motion is given to the armatures and coils. These pulleys are supported by the standard. From the bottom of the studs I′ and I, as also from those directly behind them, proceed wires which are carried along below the platform, and pass up through it between the pilliar, P, and the revolving armatures, to the shaft; there being one on each side of the axis.

Figure 46, represents a top view of the instrument. A is the case containing the armatures and coils, and H the band wheel. N, S and N, S, are the north and south poles of the permanent magnets. S′ and S′ are the yokes by which the magnets are secured to the platform, and the screws near the poles of the magnets are for the purpose of setting the magnets to any required position, laterally, and securing them in it. M and M are the tops of the two pilliars, which support the shaft of the armatures and coils. The bearings are so made as to allow the apparatus to revolve with as little friction as possible: 3 and 3 represent the set screws against the ends of the shaft, for adjusting the ends of the permanent magnets; by which means, the armatures may be allowed to pass very near the ends of the magnets without touching. 6, 7, 8, and 9 are the receiving studs, by which the wires from any other instrument may be connected with the machine. The wire, _a_, in contact with the unitrep, as before stated, is continued and soldered to the receiving stud, 6; in the same manner, _c_, also in contact with the unitrep, is connected with 7; and also 3 with 8; and _a_ with 9. The manner in which these wires, _a_, _c_, 3, and _a_, form their contact with the shaft, is seen at N and P, figure 45, of which 5 and 5 represent a section of the shaft and unitrep.

Figure 47 represents the revolving armatures and coils, with the case taken off. C and C are the two coils of insulated copper wire, surrounding two straight bars of soft iron, represented in the end view by D and D. E is the shaft. The two armatures and coils are secured to the two brass straps F, which are themselves fastened upon the shaft. The armatures are allowed to project through the straps about the sixteenth of an inch.

On each end of the shaft is attached an _unitrep_, consisting of two cylindrical segments of silver, as seen at 5 and 5, figure 45; insulated from each other, and secured to a cylinder of ivory or wood, upon the shaft, so as to revolve with it. The terminations of the coils of wire upon the armatures, are soldered to the segments of silver, and as the unitrep turns, it brings opposite ends of the wires, alternately, upon the stationary wires or conductors, P and N: (in figure 46 they are represented by _a_ and _c_, and 3 and _a_.) The opposing currents of the coils, in each half revolution, are, by this contrivance, made to form one continuous current. Hence, the name _unitrep_ (to turn together.) There being two unitreps, and corresponding conducting wires, and screw cups, the induced currents from the two coils may be combined in several ways, after the manner of combining separate batteries.

Let the wires below the base board be all properly connected with the receiving cups, as heretofore described. Then let the wire from 6, (represented by dots,) to _k_, be connected with the wire 9 and _m_; and also the wire 7 and _l_, with the wire 8 and 0. Let one of the united wires be connected with one wire leaving the coil of an electro magnet; and the other united wire be joined to the other wire of the electro magnet of the telegraph, or any other instrument designed to operate by a galvanic battery. When this preparation is finished, if the armatures and coils are made to revolve rapidly, a powerful current is formed in the induced coils, C and C, figure 47, capable of performing all the experiments generally made by means of the galvanic battery.

Dr. Page has made a very important discovery in connection with this machine, not now to be made known; but, suffice it to say, the single machine which he has now in his possession, on Christmas day, 1844, operated Morse’s telegraph, through the circuit of 80 miles; half this circuit being wire, the other half the earth. This machine makes an electro magnet sustain 1000 pounds, and melts a platinum wire one-fortieth of an inch in diameter.

_The Pole Changer._

We introduce here a description of an instrument used for reversing the direction of the galvanic current, and which is applied in the operation of several kinds of electric telegraphs. There is a variety of modes by which the same object is attained, but as this appears the most simple, we have chosen it in preference to others.

The following figures, 48, 49 and 50, are three views of the instrument as it appears when looking down upon it, in its three changes. First, that in which the current is broken and the needle vertical. Second, in which the circuit is closed and the needle deflected to the right. Third, in which the circuit is closed and the needle deflected to the left. Each figure has, in connection with the pole changer, the battery, or any other generator of the electric fluid, represented by N and P, and the galvanometer represented by G. In each of the figures, the circles numbered 1, 2, 3, 4, 5, 6, 7, and 8, represent cups, filled with mercury, let into the wood of the platform, and made permanent. The small parallel lines terminating in these cups, represent copper wires or conductors.

A, figure 48, represents a horizontal lever of wood, or some insulating substance, with its axis supported by two standards, B and C, by which it can easily vibrate. D represents an ivory ball, mounted upon a rod, inserted in the lever, and extending a few inches above it. It serves as a handle, by which to direct the elevation or depression of either end of the lever. Both ends of the lever branch out, presenting two arms each. Through each arm passes a copper wire, insulated from each other. The left hand branches support the wires which connect the mercury cups, 1 and 4, and 2 and 3, together. The right hand branches support the wires which connect the cups 5 and 7, and 6 and 8, together. The ends of these wires directly over the mercury cups are bent down, so that they may freely enter their respective vessels when required. The other wires are permanently secured to the platform. The position of the lever is now _horizontal_, and the bent ends of the wires, which it carries, are so adjusted, that none of them touch the mercury, consequently, there is no connection formed between the battery and galvanometer, and the needle is _vertical_. The ivory ball, it will be observed, is directly over the centre of the axis, and in that position required to break the circuit. Thus, the wires, 2 and 3, 1 and 4, 5 and 7, 6 and 8, are each out of the mercury, and the circuit being broken the fluid cannot pass.

Figure 49 represents those connections which are formed when the left hand side of the lever is depressed, immersing in the mercury those wires supported by it. The ball and lever are omitted for the better inspection of the wires. Now the circuit is closed, and the current is passing from P, of the battery, to the mercury cup, 1; then along the cross wire to 4; to 8; to the coils of the multiplier, deflecting the needle to the _right_; then to 7; to 3; then along the cross wire, (which is not in contact with wire 1 and 4,) to 2; to the N pole of the battery. The arrows also show the direction of the current. It will be observed that the cups 5 and 7, and 6 and 8 are not now in connection, and consequently the current cannot pass along the wires 1 and 5, and 2 and 6.

Now, if the ball, D, is carried to the right, a new set of wires, figure 50, are immersed, and those represented in figure 49, as in connection, are taken out of their cups. The fluid now passes from P, of the battery, to the mercury cup, 1; to 5; to 7; to the coils of the multiplier, deflecting the needle to the _left_; then it passes to cup 8; to 6; to 2; and then to the N pole of the battery; the arrows representing the direction of the current. It will now be found, that the cups, 2 and 3, and 1 and 4 are not in connection, and consequently the current cannot pass along the wires, 3 and 7, and 4 and 8.

Thus, it will appear, that by carrying the ball, D, to the left, the needle is deflected to the _right_; then, by carrying the ball to the right, the needle is deflected to the _left_; and that when the ball is brought to the vertical position, the needle is _vertical_. These three changes enter into the plans of several electric telegraphs, which are to be hereafter described.

_Professor Morse’s American Electro Magnetic Telegraph, invented, 1832._

To our readers the principles and arrangement of Morse’s telegraph have been fully explained in the former part of this work. We shall here present _some_ of the evidence of the time of its invention.

_Extract from a letter from S. F. B. Morse to the Hon. Levi Woodbury, Secretary of the Treasury, dated Sept. 27th, 1837._

“About five years ago, on my voyage home from Europe, the electrical experiment of Franklin, upon a wire some four miles in length, was casually recalled to my mind, in a conversation with one of the passengers, in which experiment it was ascertained that the electricity travelled through the whole circuit in a time not appreciable, but apparently instantaneous. _It immediately occurred to me, that if the presence of electricity could be made_ VISIBLE _in any desired part of this circuit, it would not be difficult to construct a_ SYSTEM OF SIGNS _by which intelligence could be instantaneously transmitted._ The thought, thus conceived, took strong hold of my mind, in the leisure which the voyage afforded, and I planned a system of signs and an apparatus to carry it into effect. I cast a species of type, which I had devised for this purpose, the first week after my arrival home; and although the rest of the machinery was planned, yet, from the pressure of unavailable duties, I was compelled to postpone my experiments, and was not able to test the whole plan until within a few weeks. The result has realized my most sanguine expectations.”

The following letters were published in the Journal of Commerce, from the originals now in possession of Prof. Morse.

_Letter of the Hon. W. C. Rives._

SENATE CHAMBER, _September 21st, 1837_.

MY DEAR SIR,—I hope you will find in my multiplied and oppressive engagements here, an apology for not having sooner answered your inquiry on the subject of your Electro Magnetic Telegraph. I retain a distinct recollection of your having explained to me the conception of this ingenious invention, during our voyage from France to the United States in the year 1832, and that it was, more than once, the subject of conversation between us, in which I suggested difficulties which you met and solved with great promptitude and confidence.

I beg leave to assure you, that it would give us all great pleasure to renew, in personal intercourse at home, the agreeable souvenirs of our acquaintance, and friendly relations abroad. I remain with great respect, Your most obd’t serv’t, W. C. RIVES.

PROF. S. F. B. MORSE.

_Letter of Capt. William W. Pell, of the packet ship Sully._

NEW YORK, _Sept. 27th, 1837_.