Изображения страниц
PDF
EPUB

may obviously obtain all the signals about to be sent, and which should, as requisite to express the letters and it were, awaken the attention of the numerals.

person on duty ?

Such an expedient has, in fact, been Such is, in general, the nature of contrived. The person in London who the signals adopted in the electric tele- desires to communicate a message to graphs in ordinary use in England, and the telegraphic agent at Edinburgh can in some other parts of Europe. actually make the clock strike at his

It may aid the conception of the will, and thus command attention. mode of operation and communication The manner in which this is accomif we assimilate the apparatus to the plished is as admirable by its simplicity dial of a clock with its two hands. and efficiency as that which we have Let us suppose that a dial, instead of just described. carrying hands, carried two needles, The quality resorted to in this case and that their north poles, when qui- is the last of those we have mentioned escent, both pointed to 12 o'clock. above, namely, the power to impart

When the galvanic current is con- the magnetic virtue at will to soft ducted under either of them, the north iron. pole will turn either to 3 o'clock or to One of the wires conducted from 9 o'clock, according to the direction London passes into the chamber of the given to the current.

telegraphic apparatus at Edinburgh, Now, it is easy to imagine a person where it is connected with a coil of in London governing the hands of such wire which envelopes a rod of soft iron. a clock erected in Edinburgh, where The ends of this rod, which has the their indications might be interpreted form of a horse-shoe, are placed in according to a way previously agreed contiguity, but not in contact, with the upon. Thus, we may suppose that detent of a striking apparatus like an when the needle No. 1. turns to 9, the alarm-bell. When a message is about letter A is expressed ; if it turns to 3, to be sent from London, this bell-wire the letter B is expressed. If the is put in communication with the gal. needle No. 2. turn to 9 o'clock, the vanic trough in London. Immediately letter C is expressed ; if it turn to 3, the subtle fluid flows along the wire the letter D. If both needles are and converts the horse-shoe rod at turned to 9, the letter E is expressed ; Edinburgh into a powerful magnet. if both to 3, the letter F. If No. 1. The attractive power which it thus be turned to 9, and No. 2. to 3, the suddenly receives irresistibly draws letter G is expressed ; if No. 2 be towards it the detent of the alarum, turned to , and No. 1. to 3, the letter and lets go the bell, which continues H, and soforth.

to ring until the agent of the telegraph It may be presumed that there can at Edinburgh answers the demand of be but little difficulty in conceiving the messenger from London, and tells how, by practice, two persons may him he is attentive. Then the London communicate with each other by such communicator withdraws the galvanic means, almost, if not altogether, as current from the bell-wire, the horserapidly as they could write and read. shoe at Edinburgh is instantly deprived

But a difficulty will doubtless suggest of its magnetic virtue, the detent fies itself to the intelligent and inquisitive back to its place by the action of a reader. It will be asked, whether a sen- spring, and silences the bell.* tinel must be kept ever on the watch to In the practical arrangement of elec. observe when a message is coming for tric telegraphs, constructed on this as the hands of our clock do not speak, principle, the magnetic needles are notice could only be received of a com- placed vertically and not horizontally, ing message by the incessant vigilance as in the mariner's compass, and they of an observer.

are kept, when not affected by the Would it not, however, be admir. current, in the vertical position, by able if we could attach to this clock a laying two needles having their poles striking apparatus, which should ad- at opposite ends, one upon the other, dress the ear the moment a message is by which means the polarity of the

* Railway Feononny, by Dr. Lardner, pp. 352-5. VOL. XXXVI.-NO. CCXI.

с

news.

system is neutralised, and then a small tablished by the company in the chief excess of weight given to one end of towns of the kingdom, whence and the combined needles is sufficient to whither intelligenceis transmitted from keep them in the ver:ical position, time to time during the day, so that when fixed upon an horizontal axis. there is thus kept up a never-ceasing

In this manner they are fixed upon interchange of news over the entire the dials already described, being free extent of that net-work of wires which to turn on their axis when affected by has overspread the country. At each a deflecting force sufficiently strong to of these stations public subscriptionovercome the small excess of weight rooms have been established, in which just mentioned.

are posted from hour to hour as they This is the principle of the telegraph arrive, during the day, the public news, now used generally in England. The which are known to be of most inteentire system, except the lines which rest to the local population, such as follow the course of the South-Eastern the money market, shipping intelli. Railway, is in the hands of a company gence, sporting intelligence, quotations incorporated by act of parliament, of the commercial markets at all chief and who, therefore, hold a virtual places, and parliainentary and general monopoly of the chief part of the telegraphic business of the kingdom.* A We take the following description central station is established in London, of the routine of business in this dein Lothbury, near the Bank of Eng- partment of the Central Telegraphic land. The lower part of the build. Office at Lothbury, from a popular ing is appropriated to the reception of author already quoted: orders and messages.

A person desiring to forward a message to any " At seven in the morning the superin. part of England, connected with Lon

tendent of the former department obtains all don, by the wires, writes his message the London morning newspapers, from which on a sheet of letter-paper, provided he coudenses and despatches to the several for the purpose, and prepared accord- electric stations the intelligence he considers ing to a printed form, having the

most useful to each. The local press of names and address of the writer, and

course awaits the arrival, and thus by eight

o'clock A.M. a merchant at Manchester reof the party to whom the message is

ceives intelligence which the rails can only communicated, in blank spaces assign.

bring at a quarter before two, and which ed to them, together with the date

cannot by rail reach Edinburgh till half-past and hour at which the message is des.

nine P.M. patched. The answer is received, “ To Glasgow is transmitted every evenaccompanied by the date and hour at ing detailed intelligence for immediate inser. at which the message arrived, and at tion in the North British Daily Mail,' which the answer was despatched.

giving everything of importance that has The tariff of charges for trans

occurred since the first edition of the London mission of telegraphic messages differs

papers. Similar intelligence is despatched to

papers at Hull and Leeds. very much, according to the desti.

" By this rapid transmission of intellination of the message, and is not

gence, the alternations in the prices of the strictly regulated by distance.

markets at Manchester, &c. &c., being alIt is found that by practice the ope- most simultaneous with those of London, the rators of the telegraphic instruments, merchants of the former are saved from being constructed on this system, are able to victimised by the latter. It is true that by communicate about twenty words per great exertions prior intelligence may elecminute, when they work with two

trically be sent by private message ; but as needles and two conducting-wires, and

the wary ones cautiously wait for the des.

patch of the Telegraph Office, it has but little at the rate of about eight words per

effect. minute when working with a single "At one o'clock information is sent to all needle.

the electric reading-rooms of the London Besides the transmission of private quotations of funds and shares up to that despatches, stations have been es- hour, thus showing the actual prices at

A Bill is now before Parliament to incorporate a competing company.

ago !"

Weather.

Wind.
W.S.W.
S.E.
S.E.
E.
W.

Rain.

which business has been done. The closing which any particular species of information prices of the French funds for the day pre- may partially interest—such as corn-markets csiing are usually annexed, and the state of requiring corn intelligence ; seaports, shipthe London wind and weather at that hour. ping news, &c. &c.

** Early in the morning the instrument "As quickly as these various despatches boys are to be seen greedily devouring (for, are concocted, the information they respecwith the curiosity, eagerness, and enthusiasm tively contain reascends through the lift,' of yoath, they appear to take great interest or wooden chimney, to the instrument dein their duties) the various matters which partment, from whence it is projected, or from all quarters at once are imparted to rather radiates, to its respective destination ; them.

and thus in every one of the Company's * One has just received intelligence by reading-rooms throughout the kingdom telegraph from Ely, announcing the result of there consecutively appears, in what would the Lynn election. Another a copy of a until very lately have been considered magic

Moniteur' extraordinary, containing the first writing upon the walls, the varied informamessage of the President of the French Re- tion which had only reached London from public to the President of the National As- all points of the compass a few minutes sembly.

** Another, that Stewart's and Hetton's were nineteen and sixpence. Gosforth eighteen

It will, however, be asked how des. shill. Holywell fifteen and sixpence. Hast- patches can be transmitted to various ings Hartley fourteen and ninepence. S Q- stations along the extensive lines of market one hun. fifty one, sold one hun. and telegraphic communication which have three-SQ.

been established, unless a separate and • Market very good-P Q.'

independent wire be appropriated to ** Another, the following characteristic

each station, which would be mani. description of the winds and weather of Old England at nine A.N. :

festly impracticable.

The answer is easy: At each station Places.

the conducting wire is carried from Southampton

Cloudy. Gosport

the main wire through the instrumentPortemouth

room of the station, and passing through London

the instrument, is carried out again and St. Ives

Very fine.
Cambridge

S.W.
Cloudy,

continued along the line by the posts Newmarket

Cloudy. as usual. It is, therefore, apparent Yarmouth lorest wife

Stormy.

that every message despatched from Sorsich

E.
Fine.

any station must affect the instruments Chelmsford

N.E.

Cloudy.

at all the other stations; and if desired, Colchester Ipswich

can be interpreted and written out at

them all. It is therefore necessary "The above description of our changeable

to provide means by which this need. climate, it occurred to us, would not very in

less labour shall not be imposed upon correctly represent the present political state of Earope.

the telegraphic agents, and so that it * Daring the day telegraphic information may be at once known for what station flashes upon these boys from the Stock Ex- or stations each message is intended. change, informing them of prices and clog- This is accomplished by the following prices of the funds and principal railway ing expedient:- The agent at the shares. With remarks.'

station from which the message is de* From the London cattle market, stating spatched first sends the current along *the number and quality of beasts, sheep,

the bell-wire. By the means already calves, pigs. Holland beasts, sheep, calves. Danish beasts. With remarks.'

described, bells are then rung at all the ** From the meat market, stating the

stations, and the attention of the agents prices of every description of meat, with re

is called. The name of the station marks.' '

for which the despatch about to be ** Also similar returns from all the other forwarded is intended, is then trans. markets we have enumerated.

mitted, and appears upon the dials at * As fast as this incongruous mass of in- all the stations. The agents at all the telligence arrives, it is, in the mode already

stations, except that to which the de. described, transcribed in writing to separate

spatch is addressed, are then released sheets of paper, which are without delay, one

from further attention, and the agent after another, lowered down to the superintendent of the Intelligence Department,' by

at the station to which it is addressed whom they are rapidly digested for distribu- interprets the signs as they are suction either to the whole of the Company's cessively transmitted, and reduces the reading-room stations, or for those lines only message to writing.

E,
E.
E.

Fine.

S.E.
S.E.

Fine.
Fine.

It will be seen, therefore, that every systein, let us suppose a person at message which is despatched, no mat. New York desirous of sending a mes. ter for what station it is intended, is sage to New Orleans. A wire of the in fact, sent to all the stations which usual kind connects the two places. the wire passes.

The end at New Orleans is coiled The telegraphs established in Eng- round a horse-shoe magnet. The end land, which alone we have here ex- at New York can be put in commuplained, are constructed on the needle nication with the galvanic trough at system, that is to say, the signals are the will of the person sending the made by the deviations of magnetic message. The instant the communi. needles, from their position of rest cation is established, the horse-shoe produced by electric currents passing of soft iron at New Orleans becomes around them.

magnetic, it attracts the small lever, Telegraphs depending on the second and presses the pencil against the paper. and third principles adverted to above, The moment the operator at New have been brought into extensive use York detaches the wire from the in America, the needle system being trough, the horse-shoe at New Orleans in no case adopted.

loses its magnetic power, and the To explain the construction and pencil drops from the paper. It is operation of telegraphs depending on clear, then, that the operator at New the power of magnetism on soft iron by York, by putting the wire in contact an electric current, let us suppose a with the trough, and detaching it, and small lever formed of steel, and ba- by maintaining the contact for longer lanced on a point. At one end of this or shorter intervals, can make the lever let a point be formed, so as to pencil at New Orleans act upon the constitute a pencil or style. Under paper, as already described, so as to the other end let a horse-shoe of soft make upon it dots and lines of deteriron be placed at such a distance, that minate length, combined in any manwhen it shall receive the magnetic ner he may desire, and separated by virtue from the electric current, the any desired intervals. leve will be drawn to the horse-shoe; In a word, the operator at New and let it be so arranged, that when York can write a letter with a pencil the horse-shoe shall lose its magnetic and paper which are at New Orleans. virtue, the pencil will fall.

Provisions in such an arrangement Now suppose that immediately are made, so that the motion of the above the pencil is placed a small paper does not begin until the mes. roller, under which a ribbon of paper sage is about to be commenced, and passes, which receives a slow progres- ceases when the message is written. sive motion from the roller. When- This is easily accomplished by the ever the pencil is raised by the magnet, same principle as has been already deits point presses on the paper which scribed in the case of the bell, which moves over it, and if it be kept pressed gives notice to the attendant in the upon it for any time, a line will be European telegraph. The cylinders traced. If the pencil be only momen- which conduct the band of paper are tarily brought into contact with the moved by wheel-work, and a weight paper, a dot will be produced.

properly regulated. Their motion is It is clear then, that if we have the imparted by a detent detached by the power of keeping the pencil for any action of the magnet, and which stops determinate time in contact with the the motion when the magnet loses its paper, or of making it only momen- virtue. tarily touch the paper, we shall be The third system, called the Electroenabled to produce lines and dots in chemical telegraph, is also exclusively any required succession ; and by sus- adopted in the United States, and pending the action of the pencil, we with the improvement which it has can leave blank space of any desired recently received, it exceeds by far in length between such combinations of efficiency and power all the other telelines and dots.

graphic arrangements hitherto tried. It is easy, therefore, to imagine how A memoir on this invention has rea conventional alphabet may be formed cently been read before the Academy by such combination of lines and dots. of Sciences in Paris, of which we

To explain the operation of this shall avail ourselves.

The imperfections of the nopille “Lt a metallic disk be providedl, corresani magnet telezraphs, which this in- ponding in magnitude with the sheet of provement removes, are stated as paper, and let this metallic desk be put in follows:

communication with a galvanic battery so as

to form its negative pole. Let a piece of ** To deflect the magnetic needle from a

steel or copper wire, forming a pen, be put in position of rest, and still more to impart

connexion with the same battery so as to

form its positive pole. Let the sheet of sufficient magnetic energy to soft iron so as

moistened paper be now laid upon

the metallic produce the necessary effects at the stations

desk, and let the steel or copper point, which of arrival, in the systems above mentioned, a galvanic current of a certain force is indis

forms the positive pole of the battery, be pensable. Lines of telegraphic communi

brought into contact with it. The galvanic cation being exposed to local and atmos

circuit being thus conipleted, the current will

be established, the solution with which the pherical vicissitu les, such a force of the

paper is wetted will be decomposed at the current cannot always be secured. This is especially the case when communications are

point of contact, and a blue or brown spot made to great distances, as for example,

will appear. If the pen be now moved upon 300 miles and upwards.

the paper, the continuous succession of spots

will form a blue or brown line, and the pen * Supposing the insulation of the supports of

being moved in any manner upon the paper, the conducting wire to be perfect, and no accidental disturbances arising from atmos

characters may be thus written upon it as it

were in blue or brown ink." pherie influence or local causes to be in operation, the strength of the electric current will nevertheless be intluenced by mere dis

The metallic desk on which the tance. When the distance is augmented to paper is placed is circular, and about a certain extent, the current may become so twenty inches diameter. enfeebled as to be incapable either of imparting the necessary magnetic power to the soft “It is fixed on a central axis, with which iron, or of deflecting the needles from their it is capable of revolving in its own plane. position of rest.”

An uniform movement of rotation is imparted

to it by means of a small roller, gently It is then shown that various other pressed against its under surface, and having causes, such as imperfect insulation,

sufficient adhesion with it to cause the move.. atmospheric vicissitudes, &c., are liable

ment of the disk by the revolution of the

roller. This roller is itself kept in uniform to intercept the action of the needle

revolution by means of a train of wheeland magnetic telegraphs; and that

work." they sometimes even destroy the coils of fine wire which are used to affect

The point of the wire, which may the magnets. The inventor of the electro-chemi.

be considered as a pen, is gently cal telegraph, Mr. Alexander Bain, pressed on this paper. When the cur. a native of Scotland, and formerly a

rent passes, it leaves a blue trace; watchmaker in that country, rejects

when the current is interrupted, it

leaves no trace. the use of needles and magnets altogether, and relies exclusively on the

It is clear, therefore, that by alterchemical effects of the electric current.

nately transferring and interrupting By this means he shows that he can

the current, such a pen will leave on obtain

the paper a succession of lines and

dots in any desired combination, pre“ 1st. Greater economy and simplicity in the cisely similar to those already deoriginal construction, and in the permanent scribed in the case of the American maintenance and management of the appara- system of magnetic telegraph.

But the prominent feature of this “ 2nd. Increased celerity and certainty, and less liability to error in the transmission of

system, which confers on it an immea. communications."

surable superiority over all which pre

ceded it, is the extraordinary celerity The mode of construction and opera

of which it is susceptible. We have tion of the electro-chemical telegraph already stated that, in the experiments is as follows:

made with this apparatus before the

Committees of the Institute and the " Let a sheet of writing paper be wetted

Legislative Assembly at Paris, dewith a solution of prussiate of potash, to spatches were sent along a thousand which a little nitric and hydrochloric acid miles of wire, at the rate of nearly ave been added.

20,000 words an hour.

tus;

« ПредыдущаяПродолжить »