3. The apparatus for the sudden reversing of the current, or the com

mutator (pole changer).

Fig. 20.

B

E

E

OF

gr

In the column A, fig. 20, are two or three strong magnet bars (each of 25 pounds) united in one strong magnet-their poles of the same name (like poles) are visible at B. Over these bars the reel E is placed (of course having a hole for the bars to pass through), and around its external surface a copper wire (insulated by silk winding) is wound.

At the first arrangement, Gauss gave the reel 1050 coils; by a late arrangement, he increases the number of coils to 3537, with a length of wire of about 3600 feet; and still later, he used a reel

with 7000 coils with a length of wire of more than 7000 feet.

The two ends, g g', of this reel, E, (which on account of their inductive action are called inductors) are in connexion with a commutator (pole changer), and through that with the two principal conducting wires of the telegraph. If the inductor is taken by the two handles F F', and suddenly drawn off the magnet bars on which it rests, and immediately, without turning it round, replaced in its former resting place, there results two induction currents, one immediately after the other, in opposite directions, passing through the conducting wire; the duration of these currents is very short. Their intensity depends upon the strength of the united magnets in A, upon the number of coils in the inductor E, and upon the distance these coils are from the magnets.

Fig. 21 represents the observing apparatus.

Whilst the inductor is set up at the station whence the signal is to be telegraphed, the observing apparatus is placed at the station where the communication is to be received.

It consists of a strong multiplicator, H H, that is to say, of a copper frame, around which an insulated wire is coiled. The two ends of the wire g g are connected with the two chief conducting wires coming from the o her station, so that the multiplicator wire forms with the wire coiled on the inductor E, fig. 20, a single closed wire circuit.

At first, the multiplicator had 270 coils of wire, 2700 feet long; in later trials, it had 610 coils of wire, more than 6000 feet long.

In the coils of this multiplicator, there hangs for a magnetic needle a magnetic bar, M M, of at most 4 pounds in weight (later, 25 lb. magnetic bars were used), which is suspended by a thread easily movable in the little ship L. This thread consists of 200 parallel cocoon threads, and is fastened to a wooden screw, P Q P, at the ceiling of the room, by which it can be raised or lowered.

On the brass rod K, which passes through the copper frame H H, there is a vertical mirror, N, which turns with the magnet, and is directed in such a manner towards the cypher scule, m m, fastened at the foot of the stand of the spy-glass, R, that the image of the parts of the scale can be seen in the mirror through the spy-glass.

3. The apparatus contrived by Gauss for the rapid change of the direction of the current was somewhat complicated-but any other simple commutator can be used for the same purpose.

The following is the mode of using this telegraph: At the station from which a communication is to be sent, the inductor E, fig. 20, is suddenly drawn off, and again, without turning it round, thrust down upon the magnet pole B, by which means two induction currents of opposite directions are passed through the conducting wire.

By means of the first current, the magnet in the observing apparatus, fig. 21, at the other station, through the action of the multiplicator's coils, is made to diverge in a determined direction, for example, to the right. By means of the second current in the opposite direction, it is immediately stopped, so that the magnet can make no further excursions, but only, in consequence of the two opposite currents, makes a little lively vibration. to one side, and then immediately remains quite still.

These small motions of the magnet are observed through the spy-glass R, fig. 21, in the mirror N.

In a state of rest, the image of the null point of the scale, mm, is visible through the spy-glass; by the motion of the magnet, the mirror is also moved, and reflects to the spy-glass another part of the scale. In this manner, the smallest motion of the magnet is perceptible by the spy-glass.

Accordingly as the commutator (which is directly attached to the inductor) is fixed, the first induction current passes in one or the opposite direction through the conducting wire-and therefore, by a sudden drawing off and thrusting down of the reel E, fig. 21, a magnetic vibration to the right or left at the other station can be produced at pleasure.

By an ingenious combination of several magnetic motions, to form a signal, Gauss and Weber were able to make all requisite signs (letters and cyphers) with these two motions (first blows).

-

The following are the alphabetical signs, as arranged:

The variations of the magnetic needle signify a letter; I denotes a variation to the left, and r to the right, and by the combined deflexion of the needle, words and sentences may be transmitted.

Experiments of Messrs. Taquin and Ettieyhausen.

Messrs. Taquin and Ettieyhausen made experiments with a telegraphic line over two streets in Vienna, 1836. The wires passed through the air and under the ground of the Botanic Garden.-Polytechnic Central Journal, 1830, Vail Electro-Magnetic Telegraph, p. 189.

MORSE'S ELECTRO-MAGNETIC TELEGRAPH.

In the latter part of the year 1832, Samuel F. B. Morse, an ingenious American artist, while on a voyage homeward from Europe, conceived the idea of an electric or electro-chemical telegraph, and devised a system of signs for letters, to be marked by the breaking and closing of the electric or galvanic current.

Dr. C. T. Jackson, of Boston, a fellow passenger, well versed in the science of chemistry and electricity, and having witnessed numerous experiments during a recent visit to Paris, afforded him considerable. assistance.

The following is a brief account of the methods proposed:

1st. That electricity might be made visible in any part of the circuit, by dividing the wire, when a spark would be seen at the intersection. 2d. That it could be made to perforate paper if interposed between the disconnected wires.

3d. Saline compounds might be decomposed, so as to produce colors on paper.

The 2d and 3d projects were adopted for future trial, since they would furnish permanent records; the saline substances mentioned, were the acetate and carbonate of lead, which when decomposed by the galvanic current, left black marks on the prepared paper; again, tumeric paper, moistened in a solution of sulphate of soda, left brown marks on the passage of the current, produced by the disengaged alkalie. Platina points were also proposed to effect the changes in color.

Mr. Morse experimented for some time after arriving in New York, independent, however, of Dr. Jackson. While on board the Sully, Dr. Jackson doubtless materially aided Mr. Morse in his conception of the electric telegraph, though they do not appear to have had any subsequent connexion, nor was the instrument they devised brought into practical

use.

From a careful examination of all the evidence given by the passengers on board of the packet ship Sully, the telegraph devised by Morse and Jackson was not an electro-magnetic telegraph, but an electric or VOL. XXII.-THIRD SERIES.-No. 2.-AUGUST, 1851.

11

electro-chemical telegraph (see letters of Dr. Jackson to Mr. Morse, and Morse's pamphlet, and letters of J. Francis Fisher, Esq., of Philadelphia). Mr. Morse cast some type in 1833, but from limited circumstances, was compelled to desist from farther experiment, until his appointment to a professorship in the University of New York, in 1835, when he formed the annexed mechanical arrangement, which is interesting from the fact, that it is the basis on which a long series of improvements have been made to bring the instrument to its present unique construction. He exhibited it in January, 1846, to Mr. L. D. Gale, a colleague professor in the University, of high scientific attainment, who afterwards joined Mr. Morse in his enterprise, and made some useful suggestions for its improvement. But becoming satisfied that the electromagnetic power was more available for telegraphic purposes, as exemplified by the experiments of Prof. Henry and his own trials, he directed his attention to that agent. Mr. Gale gives the following description of the instrument, in his evidence in the case of F. O. J. Smith versus Hugh Downing:

"A train of clock wheels were used to move a strip of paper, one half an inch in breadth. A, B, and C, are cylinders; the paper is unrolled from passing over the cylinder B to C, where it is connected to the clock work D, moved by the weight E. F is a wooden triangular shaped pendulum, suspended from the pivot f, over the centre of the cylinder B; its vibrations were across the paper, or at right angles to the motion of the latter. Through two cross-pieces in its lower part was fixed a pencil case, containing a pencil moving readily up and down, but kept in contact with the paper by a light weight, g.

An electro-magnet was fixed on the shelf h, which projected from the frame XX; this magnet attracted an armature affixed to the pendulum. One of the conductors of the magnet helix, passed to the single plate galvanic battery I, while the other joined the cup of mercury at the port rule K. The other pole of the battery was connected by a wire to the other cup of mercury J. The lower table represents a port rule; it consists of a rude frame containing two cylinders L L, two inches in diameter and two inches long, one turned by a crank, and that turning the other by a band one and half inch in width.

M, is a rule or composing stick, made of two small thin rules, two feet long, placed side by side, separated sufficiently far to form a trough for the type; the tops or cogs of the latter, are seen rising above the top of the rule M. A lever O O, is suspended from the united top of two standards that rise from the sides of the long frame of the post rule, on one end of which is a fork of copper wires that plunges when the lever is depressed into the two mercury cups K and J. A weight is attached to the other extremity to keep it down, and beneath this is a tooth, similar to the keys of a hand organ. There were eleven types one-eighth of an inch thick, having from one to five projections called cogs, save one that was used for a space. The first five numbers consisted from one to five cogs respectively, followed by a space, while the second five were the same, only having a long space double that of the first.

If, as an example, it was desired to send the number 456, the types 4, 5 and 6, with a space to separate them from the successive ones, were set up in the port rule M, which was placed on the bands of the port rule and sent forward by turning the crank; the cogs of the type operating the lever O O, broke and closed the circuit at the battery I; this being done, the magnet h, attracted the pendulum F, and moved the pencil g, about one-fourth of an inch; the pencil being in contact with the paper while it was moving, a continuous straight line was marked on it if the pendulum was stationary either at one or the other limit of its motion; but when attracted by the magnetic force, it marked a V shaped point as seen in the drawing; the points were marked on the moving paper as there shown by the successive breakings and closings of the circuits through the cogs of the type; the extremities of the V shaped marks were recognised for the figures by their number.'

A dictionary was prepared, in which words were arranged in a manner that the numbers would represent them.

Mr. Morse found himself unable to make use of his instrument for great distances, from the resistance to, and dissipation of, the electrical current along the conductors. To overcome the difficulty, he adopted in the spring of 1837, a receiving magnet and a relay or repeating circuit. We