indebted in this country for all the advan-, account of the innumerable inventions, all tages of telegraphic communication. more or less ingenious, by which telegraphic

Our limits will not permit us, nor indeed communications are generally transmitted. is this the proper place, to give an account | It is difficult for ordinary readers to underof the fine discoveries of Arago and Fara- stand these operations even with the aid of day, on the magnetic properties of electric good diagrams,* and those who are desirous currents. MM. Arago and Ampere magnet- of making themselves master of the apparaized needles instantaneously by placing ihem tus commonly employed, will do this most within a helix of insulated copper wire, so satisfactorily by visiting any of the stations that the electric current passed in a direction where an electric telegraph is placed. Our perpendicular to their length. Mr. Stur- object in the present article is to give some geon of Woolwich applied this principle to account of the general telegraphic system, the construction of temporary magnets of and of the labors and services of those who great power by merely surrounding soft iron, have been the means of introducing the eleceither in the form of bars or of a horse shoe, tric telegraph on our railways, and who have with insulated coiled wire. The soft iron be- invented remarkable contrivances for comcomes a powerful magnet while the electric municating intelligence, such as the printing current is passing through the coil, and loses telegraph, the electro-chemical telegraph, the its power ihe moment the current is stopped. autograpbic telegraph, and any others that In this way Mr. Joseph Henry, now the dis- are distinguished from those commonly used tinguished Secretary to the Smithsonian In- by remarkable peculiarities. stitution, produced magnets which were ca- We have already seen from the experipable of lifting several tons, and the same ments of Sir W. Watson, and the fact was principle has been employed by Logeman evident from every future experiment, that and others for communicating permanent the electric power was transmitted along magnetism to steel.

wires instantaneously, or in so short a time Mr. Faraday's beautiful discovery of elec- that its velocity could not be appreciated by tro-dynamic induction in 1832, was a most the ordinary instruments by which time is important step in the improvement of the measured. Any more accurate measure of electric telegraph. He demonstrated by two its velocity was of no consequence for telefine experiments, that an electric current is graphic purposes. Means, however, have capable of developing at a distance by induc- been taken to obtain a rude estimate of its tion electrie currents in a conducting wire. velocity, which of course must depend on the If we suddenly bring near to any part of a conducting power of the transmitting wire, conductor forming a closed circuit another though it does not upon its thickness. By conductor traversed by a current, we pro- a very ingenious apparatus Mr. Wheatstone duce instantaneously on the first conductor a found that the electric force moved along a current moving in a direction contrary to copper wire at the rate of 288,000 miles in a that of the inducing current, or that brought second. According to the more recent exnear the conductor, and when we reverse ihe periments of MM. Fizeau and Gonelli its veinducing current we produce instantaneously locity is only 112,680, less than half of the in the first conductor a second current mov- preceding estimate. In the iron wire eming in the same direction as the current that ployed for telegraphic purposes, its velocity, is reversed. Mr. Faraday also found that a according to MM. Fizeau and Gonelli, is only magnet is capable of inducing similar cur- 62,000 miles in a second ; according to Prorents in a conducting wire, and that the phe- fessor Mitchell of Cincinnati 28,500; and acpomena of induction may be produced in the cording to Professor Walker of the United conducting wire itself, an effect which is States, 16,000 miles. But it is obvious, that termed the induction of a current upon itself. whichsoever of these velocities is the correct Mr. Faraday was thus led to the construc. one, the electric influence is transmitted in tion of a magneto-electric machine which so short a time that an effect produced was greatly improved by Pixii, Saxton, and at one station is produced simultaneously Clarke, and extensively employed for tele. with the effect produced at another. graphic purposes.

In order to transmit messages along the Such is a brief notice of the history of the electric telegraph, and of the principal dis

* The reader will find the most complete and incoveries in electricity and magnetism, upon Dr. Lardner's admirable chapter on the subject, in

telligible description of telegraphic apparatus in which the present telegraphic apparatus is the third and fourth volumes of bis Museum of founded. It is not our intention to give any | Science and Art,

telegraphic wires, a certain amount of elec- | being injured by human hands. M. Siemens tric power is required, and this force must be bas observed two interesting facts on these increased in proportion to the length of the lines. In the one a diminution of the effect wire. A large wire, however, will transmit, is produced by inverse currents arising from more electricity than a small one, in propor- the wires acting like a Leyden phial. The tion to the squares of their diameters, or the gutta percha which coats the wire is the areas of their section. According to some glass of the phial, the wire is the internal accurate experiments made by M. Pouillet, a coating of the phial, and the damp ground distinguished member of the Institute of is the external coating, so that the opposite France, a, voltaic battery of ten pairs of electricity of the ground acts upon, and neuplates will supply electricity sufficient for tralizes to a certain extent the internal electelegraphic purposes by means of a copper tricity of the wire. It was apprehended wire one-eighth of an inch in diameter, and that this disturbing cause would have inter600 miles in length. A force of much less fered with the working of the subterranean intensity, however, is amply sufficient, as it wires, but the Magneto-Electrie Telegraph is easy to strengthen the current by batteries Company, who have in work 900 miles of at intermediate stations.

subterranean wire, and who often send their Having obtained a cheap and durable line messages through 500 miles without any for conducting the electric influence, and a stoppage, have not experienced any inconve. simple power for generating it of sufficient in-nience from it. The other phenomenon obtensity, the next step is to place the lines or served by M. Siemens is the electrical influwires in a proper position. The general ence upon the wires by the Aurora-Borealis. practice has been to support them by posts During the brilliant display of this phenomplaced at the distance of sixty yards. On enon on the 18th October, 1848, he observed some lines the distance of the posts is much currents varying in intensity and direction, in greater; and on the great telegraphic line the line between Berlin and Coethen, 20 between Turin and Genoa, the wires are car- German miles in length, the direction of ried across extensive ravines and valleys, which was E.N.E. to W.S.W., nearly perfrom half a mile to three-quarters of a mile pendicular to the magnetic meridian. During in width, without any support whatever, and the prevalence of this meteor, the electric at an enormous height above the ground. telegraphs in England were temporarily unWhen the line reaches Turin it passes under fitted for use. ground, and when it arrives at the Maritime In the telegraphic lines established in Alps it stretches from crest to crest, hiding India by Dr. O'Shaughnessy, he has adopted itself again in the earth till it terminates at both the aërial and subterranean system. the ducal palace in Genoa.

He found that the wires used in England M. Siemens, whose ingenious telegraph were quite insufficient in India. In his exreceived a Council Medal at the Great Ex- perimental line of eighty miles from Calcutta, hibition, and which is used on all the Prus- he was obliged to employ iron rods resting sian lines, and those in the north of Germany, on bamboos. Flocks of heavy birds like the recommended the subterranean system of adjutant perched upon them, and groups of construction, and had it carried into effect on monkeys followed their example, while upwards of a thousand miles of German loaded elephants broke them down when railway. By carefully covering the copper they came in their way. He therefore used wires, which were about the 50th of an inch thick galvanized wires suspended at the in diameter, with gutta percha, to prevent height of fourteen feet upon posts upwards the escape of the electricity, by placing them of 200 yards apart, and so strong was the about 24 feet deep in iron tubes, and by in- system, that a soldier suspending bimself genious methods of discovering the locality from the middle of one of these long wires of any defect either from the insulating coat. produced on it but a small curvature. In ing or from the copper wire, he found the the subterranean system, where it is used in system answer so well, that at the end of India, Dr. O'Shaughnessy lays at the depth three years the wires had not suffered the of two feet his wires, coated with gutta perslightest change. There are obviously many cha, on wooden sleepers saturated with arseadvantages in the subterranean system. The nic, in order to defend them from the white wires are not influenced by rain or snow- ants, which we suppose, like the rats in the they are secure against storms and hurri- north of Germany, reckon gutta percha a canes, and their locality in the earth, as well | great luxury. as upon the railway path, protects them from The wires employed for telegraphic purposes are commonly made of iron about the all communication between the wire of the stasixth part of an inch in diameter. They are tion is cut off by the destruction of the fine wire. coated with a plating of zinc, by what is Cases have occurred in which these wires have called galvanization. As zinc is very oxyd- | been made red hot, and even melted. able, it is soon converted by the air and by When the system of wires is thus erected moisture into an oxyde of zinc, which being either above or below the ground, it becomes insoluble in water, protects the wire from rust interesting to see at what rate signals or and corrosion. M. Haighton, however, has words can be transmitted to great distances. found that the gases from the smoke of large About three years ngo some interesting extowns converts the oxide into a sulphate, periments on this point were made in Paris which being soluble in water permits the wire by M. Leverrier and Dr. Lardner before to be corroded, and to such a degree that he committees of the Institute and the National found his wires reduced to the dimensions of Assembly. In one experiment, a message of a common sewing needle in less than two | 40 words was sent 168 miles, and an answer years. Some very peculiar conditions of the of 35 words returned, in the space of 4 minwires in America, which are not galvanized, utes and 30 seconds. In another experiment, have been discovered. On the telegraphic a message of 282 words was transmitted lines which cross the extensive prairies of the along a continuous wire 1,082 miles long. Missouri, the telegraphs refuse to act in the “A pen,” says Dr. Lardner, "attached to months of July and August during the four the other end, immediately began to write hottest hours of the day, from 2 to 6 o'clock ! the message on a sheet of paper moved under

Many inferior contrivances, which require it by a simple mechanism, and the entire diagrams to make intelligible, and which message was written in full in presence of will be found clearly described in Dr. Lard the Committee, each word being spelled ner's volumes, have been adopted to insulate completely and without abridgment, in fiftythe wires in passing the posts. The wires two seconds, being at the average rate of five at the posts generally pass through tubes of words and four-tenths per second !” This earthenware or of glass, or they rest upon was done by Mr. Bain's electro-chemical cylinders or rollers of the same substance. telegraph, which the writer of this article saw In order to prevent the bending of the wires, in operation at the time when this experiment and their mutual interference in high winds, was made in Paris, and which, from its pecuan apparatus is placed at distances of half a liarly ingenious construction, we shall enmile for tightening them, and the posts where deavor to describe. this is done, and which are larger than the The sheet of paper which is to receive the usual ones, are called winding posts.* written message is wetted with an acidulated

We bave already stated that the electricity solution of the ferroprussiate of potash, and of the aurora, comparatively feeble as it is, placed upon a plate of metal. "If we now deranges the operation of the telegraph; but take a metallic point or style, and place it in the influence of atmospheric electricity in contact with the paper, and conceive a curthunder-storms is of course much more inju- rent of electricity to pass through the style, rious, and is often dangerous at telegraphic it would enter the copper plate through the stations. The natural remedy for this is to paper and make a blue spot, so that we could place conductors on the top of each post, easily write upon the paper, as if blue ink which is very easily done ; but at telegraph streamed from the point of the style. Let ic stations very beautiful and efficacious con- us now suppose that the upper end of the trivances for their protection have been style is connected by a wire with the positive invented by Mr. Walker of the South-Eastern pole of a voltaic battery, and the metallic Company and M. Breguet of Paris. A re- plate with the negative pole, a current will markably fine copper wire is placed between flow through the point of the style whenever the main wire and the station, so that any it is brought in contact with the paper, and current of electricity imparted to the main will decompose the prussiate of potash, one of wire must pass through the fine one before the elements of which will mark it with a dark it reaches the station : but the effect of pow- blue spot. If the paper is moved or drawn erful electricity upon a fine wire is to fuse or aside, the style will trace a blue line upon it. deflagrate it, owing to the difficulty that it has if the current is stopped at different intervals, in passing along so narrow a channel; so that the blue line will be stopped also, and we • If we place our ear close to one of these posto blue lines, in proportion to the length of time

shall have short or long spaces between the during a breeze, sounds like those of falling water are distinctly heard.

during which the current has been stopped.


Mr. Bain has contrived various ways of tween the perforations, the electric current moving the paper beneath the style, but the does not pass, and the style makes no blue one which he prefers is to lay a large circu- mark, but leaves a corresponding blank. In lar disc of it upon a metallic plate of the this way the message of perforation is transsame size, which is made to revolve by ferred in blue lines to the chemical paper a clock-work round its own centre and in its thousand miles off, and arranged in a spiral own plane, while the style has a slow motion from the centre to the circumference of the from the centre to the edge of the disc. paper disc. A boy previously taught reads The consequence of these two movements is, this record to a clerk as quickly as if it were that the style will describe a spiral com- in ordinary type. mencing at the centre of the disc of paper, The reader can not fail to be struck with and terminating at its edge; and when the the singular beauty and ingenuity of this current passes through the circuit uninter-contrivance, imperfect as our description of ruptedly, this spiral will be a continuous blue it must be. When we saw in Paris the whole line, but if the current is interrupted, it will operation of perforating the message, and reconsist of short blue lines and white spaces cording it in blue lines at the other end of of different lengths.

the wire, it seemed more like magic than The next step is to construct an alphabet l'any result of mechanism which we bave ever for this telegraph, which is done as follows:- seen. The dry steel point, when tracing its The lettera is represented with one short spiral path, actually seems to be depositing line thus -, b - – with one long and blue ink upon the paper.

But it is not two short lines, c

with the same merely ingenuity that is the characteristic of lines differently placed, d with four lines Mr. Bain's Telegraph. In is unlimited in its

é with two short ones --, f quickness, and unerring in its accuracy; and

with two long ones, and so on, the it has another advantage of requiring a greatest number for any letter being four lines, battery of much less power than otber forms with short and long ones differently placed of the telegraph. An example of the value

The message being supposed to be written of its accuracy was recently shown in a case out, a narrow ribbon of paper, about half an where the importance of a single figure was inch wide, after being unrolled from a cylin- experienced. In an agitated state of the der, is made to pass between rollers under a funds, a stock-broker in London received punch, which by an ingenious mechanism from a distance an order to purchase at a punches out a hole beneath it, and through certain time of the day, £80,000 of consols. the paper when it is passing. Two or three The broker doubted the accuracy of the of these holes form the short line a -, and number from the magnitude of the sum, and several form the long lines, such as f as the message had been sent by the record

The operator is thus able to make ing instrument, it was found that the real sbort or long lines at pleasure, and can there- message was to purchase only £8000 of confore perforate in the paper-ribbon or message sols, the transcriber having by mistake instrip the message which is to be sent. In serted a cipher too many. this work a number of agents may be simul- But this telegraph has another advantage taneously employed in perforating messages which no other possesses. It is a cipher for the telegraph, to which they are applied telegraph, by which individuals may commuin the following manner :

nicate with their friends, or companies with The perforated message-strip is now coiled their correspondents, or governments with upon a roller, and placed on an axle attached their distant functionaries. The short and to the telegraphic machinery. The extremity long lines of the telegraphic alphabet may be where the message commences is then placed varied in innumerable ways, which it would on a metallic roller in connection with the be impossible to decipher, and a punching positive pole of the voltaic battery, and is machine, which would cost little, Inight be pressed upon the roller by a small metallic either in the possession of individuals, or at spring terminating in points like the teeth of their command in the town or village where a comb This spring communicates with the they reside. Any arrangement of this kind, conducting wire, and when it falls into the however, is not likely to be adopted, except perforation of the paper, the electric current in a small number of cases, until the expense passes to the point of the recording style, of telegraphic despatches is reduced to a very which then makes a blue line corresponding moderate sum. But if such a change should to the one in the perforated stripe, but when take place analogous to the penny-post, as the spring rests upon the white paper be- | Dr. Lardner has stated, Mr. Bain's telegraph


would be the only expedient of all those | unfortunate in not deriving from them those hitherto contrived by which such augmented material benefits which their invention so demands could be satisfied, the instruments amply confers upon others; but we trust in common use, of whatever form, being that the time is not distant, when his merits utterly inadequate to the purpose. How will be appreciated and rewarded. this would be effected by Mr. Bain's tele- Mr. Bain's Electro-chemical Telegraph is graph, Dr. Lardner has satisfactorily shown. in use upon 1,200 miles in the United States,

Nothing more,” he says, “would be neces- and such is its value, as we are informed by sary than to engage a great number of per- Mr. Whitworth, in bis Report on the Indussons, for the purpose of committing the trial Exhibition of New York, that in damp despatches to the perforated ribbons. If a and rainy weather, when Morse's telegraph great number of despatches, short or long, be works imperfectly, they find it convenient to brought at once into the telegraphic office remove the wires from it, and connect them for transmission, let them be immediately with Bain's in which “they find it practicable distributed among a proportionate number of to operate when communication by Morse's the persons engaged in the preparation of system is interrupted.” the ribbons. A long despatch might be di- A very ingenious and striking modification vided into several portions, and distributed of the Electro-chemical Telegraph has been among several, just as a manuscript report, invented by Mr. Bakewell, and was reward intended for publication in a journal, is dis- with a Council Medal at the great Exhibition. tributed among several compositors. When It has been called the Autographic Telegraph the despatches thus distributed should be from its conveying the message actually committed to the ribbons, new ribbons might written in the handwriting of the person that be connected together, so as to form longer sends it. The message is written upon a continuous ribbons, which being put into the sheet of tinfoil, with a thick ink like varnish, telegraphic instruments, would be sent to which, when dry, is a non-conductor of electheir destination at the rate of 20,000 words tricity. This sheet is rolled round a metallic an hour on each wire !"

cylinder, so that the lines of the writing are In certain cases, such as the transmission parallel to its axis. A blunt steel point or of reports of debates, or speeches of public style is made to move over the message in interest, or Government despatches, the same lines, parallel to the axis of the cylinder documents are required to be sent to different wbich revolves round its axis, as if the steel places. We have then only to take the per- point were obliterating the message by a forated ribbons to the different wires belong. number of parallel lines. The style, like that ing to different places; or, as Dr. Lardner in Bain's telegraph, is connected with the suggests, two or more ribbons might be per- telegraphic wire, at the other end of which forated simultaneously, and the message is a similar steel point, which draws similar which it contains sent at the same instant to lines upon a sheet of paper wetted with a different telegraphic stations, and transmitted solution of prussiate of potash, and rolled in various directions. “In this view of the upon a metallic cylinder. When the style, question,” says Dr. Lardner, “the system of which passes over the written message, rests Bain is to the common telegraph what the upon the tinfoil

, the electric current passes steam-engine is to the horse, – the power to along the wire, and the writing style at its the hand-loom,—the lace frame to the cush- farther extremity makes a blue line, but ion,ấthe self-acting mule to the distaff, or whenever it passes over the non-conducting the stocking-frame to the knitting needle." varnish, the current is stopped, and the re

With such peculiar advantages, which we cording style leaves a white space of the same trust will soon be realized, all letters which breadth as the breadth of the varnished lines. require despatch will be sent by telegraph, In this way, when the style has passed over the and the post-office will be employed only for whole of the message in parallel lines, the resending heavy orders or letters, when there cording style will have left the message written is no occasion for extraordinary celerity of in white letters of exactly the same form, and transmission. When the sixpenny or the relieved by the blue ground produced by the penny telegraph comes into play, Mr. Bain blue lines drawn on the chemically prepared will stand forth as the greatest of our tele- paper. This operation is analogous to that graphic inventors, and Scotland will be able of the workman who is cutting letters upon to boast that the telegraph was invented and boxwood for a wood-cut. In cutting out the perfected within her domains. Mr. Bain has letter 0, for example, he cuts away all the hitherto, like all other great inventors, been I wood excepting what forms the circle. In

« VorigeDoorgaan »