AMERICAN  See also:

• CODE (Lat. codex)

CODE A B C D E F G H Open See also:

• CIRCUIT (Lat. circuitus, from circum, round, and ire, to go)

circuit, single-current See also:

• SYSTEM

system . plates . It will be observed that the circuit is not in this See also:

• CASE
• CASE, JOHN (d. 1600)

case actually open; the meaning of the expression " open circuit " is " no See also:

• BATTERY (Fr. batterie, from battles, to beat)

battery to See also:

• LINE

line." In normal circumstances the See also:

• INSTRUMENTS

instruments at both ends are ready to receive, both ends of the line being to See also:

• EARTH
• EARTH (a word common to Teutonic languages, cf. Ger. Erde, Dutch aarde, Swed. and Dan. jord; outside Teutonic it appears only in the Gr. 'pq'e, on the ground; it has been connected by some etymologists with the Aryan root ar-, to plough, which is seen in
• EARTH, FIGURE OF
• EARTH, FIGURE OF THE

earth through the receiving instruments . A See also:

• SIGNAL

signal is sent by de-pressing the See also:

• KEY
• KEY (in O. Eng. tang; the ultimate origin of the word is unknown; it appears only in Old Frisian kei of other Teutonic languages; until the end of the 17th century the pronunciation was kay, as in other words in O. Eng. ending in aeg; cf. daeg, day; clang
• KEY (the phraseograms being indicated by hyphens)
• KEY, SIR ASTLEY COOPER (1821-1888)
• KEY, THOMAS HEWITT (1799-1875)

key K, and so changing the contact from a to b, and w thus putting the battery to line . On circuits where the See also:

• TRAFFIC

traffic is small it is usual to make one See also:

• WIRE (A.S. wir, a wire; cf. Swed. vire, to twist, M.H.G. wiere, a gold ornament, Lat. viriae, armlets, ultimately from the root wi, to twist, bind)

wire serve several stations . At an intermediate or wayside station W, a " switch " S, consisting of three blocks of See also:

• BRASS
• BRASS (O. Eng. braes)

brass fixed to an insulating See also:

• BASE

base, is sometimes used current System . W may be made the terminal station of LI by inserting plug 3, and of L2 by inserting plug 2, or the instruments may be cut out of circuit by inserting plug 1 . In See also:

• ORDINARY (med. Lat. ordinarius, Fr. ordinaire)

ordinary circumstances the messages from all stations are sent through the whole line, and thus the operator at any station may transmit, if the line is See also:

• FREE

free, by manipulating his key . The connexions for single-current working on the " closed-cir- cuit " system are shown in fig . 17 . It differs from the open circuit in only requiring one battery (although, as in the figure, closed- See also:

• HALF

half of it is often placed at each end), in having the re- circuit ceiving See also:

• INSTRUMENT (Lat. instrumentum, from insincere, to build up, furnish, arrange, prepare)

instrument between the line and the key, and in system. having the battery continuously to the line . The battery is kept to the line by the See also:

• BAR
• BAR (0. Fr. barre, Late Lat. barra, origin unknown)
• BAR, CONFEDERATION OF
• BAR, FRANCOIS DE (1538-1606)
• BAR, THE

bar c, which See also:

• SHORT, FRANCIS JOB (1857– )

short-circuits the keys .

When signals are to be sent from either station the operator turns the switch c out of contact with the stop b, and then operates precisely as in open circuit sending . This system is more expensive than the open-circuit system, as the battery is always at See also:

• WORK

work; but it offers some advantages on circuits where there are a number a of intermediate stations, as the circuit is under a See also:

• CONSTANT, BENJAMIN (1845-1902)

constant electromotive force and has the same resistance no See also:

• MATTER

matter which station is sending or receiving . The arrangement at a wayside station is shown at W . When the circuit FIG.17.—Closed Circuit, Single- is See also:

• LONG, GEORGE (1800-1879)
• LONG, JOHN DAVIS (1838– )

long and contains a large current System. number of stations, the sending battery is sometimes divided among them in See also:

• ORDER
• ORDER (through Fr. ordre, for earlier ordene, from Lat. ordo, ordinis, rank, service, arrangement; the ultimate source is generally taken to be the root seen in Lat. oriri, rise, arise, begin; cf. " origin ")
• ORDER, HOLY

order to give greater unirmity of current along the line . When only one battery is used the current at the distant end may be considerably affected by the leakage to earth along the line . If long circuits were worked See also:

• DIRECT

direct with ordinary instruments, high battery See also:

• POWER [WILLIAM GRATTAN] TYRONE (1797-1841)

power would be required in order to send- sufficient stogie- current to actuate the apparatus . In such cases it is current usual to employ a See also:

• LOCAL

local battery to produce the signals, relay and to See also:

• CLOSE
• CLOSE (from Lat. clausum, shut)
• CLOSE, MAXWELL HENRY (1822-1903)

close the local battery circuit by means of a working. circuit-closing apparatus called a relay, which is practi- cally an electromagnetic key which has its See also:

• LEVER (through O. Fr. leveour, levere, mod. levier, from Lat. levare, to lift, raise)
• LEVER, CHARLES JAMES (1806-1872)

lever attached to the See also:

• ARMATURE (from Lat. armatura, armour)

armature of the magnet and which can be worked by a very weak current . The arrangement at a station worked by relay on the " single-current " system is shown in fig . 18, where L is the line wire, joined through the key K to one end of the coil of the relay magnet R, the other end of which is put to earth . When a current passes through R the armature A is attracted and the local circuit is closed through the armature at b . The local battery B, then sends a current through the in- Working. the signal . In the See also:

• FORM (Lat. forma)

form of relay indicated in the figure the armature is held against the stop a by a See also:

• SPRING (from " to spring," " to leap or jump up," " burst out," O. Eng., springau, a common Teut. word, cf. Ger. springer, possibly allied to Gr. QnrFpxecOac, to move rapidly)

spring S .

" Single-current " working by means of a non-polarized relay (fig . 18), although See also:

• GENERAL
• GENERAL (Lat. generalis, of or relating to a genus, kind or class)

general in See also:

• AMERICA

America, is not adopted in See also:

• ENGLAND
• ENGLAND, THE CHURCH OF

England . See also:

• DOUBLE
• DOUBLE (from the Mid. Eng. duble, the form which gives the present pronunciation, through the Old Er. duble, from Lat. duplus, twice as much)

Double- In the latter See also:

• COUNTRY (from the Mid. Eng. contre or contrie, and O. Fr. cuntree; Late Lat. contrata, showing the derivation from contra, opposite, over against, thus the tract of land which fronts the sight, cf. Ger. Gegend, neighbourhood)

country, when such working is resorted to, The See also:

• SIEMENS, ERNST WERNER VON (1816-1892)
• SIEMENS, SIR WILLIAM [KARL WILHELM] (1823-1883)

Siemens polarized relay, shown in fig . 19, consists of an armature a, pivoted at one end h in a slot at one end N of a permanent magnet m, the other See also:

• POLE (FAMILY)
• POLE, REGINALD (1500-1558)
• POLE, RICHARD DE LA (d. 1525)
• POLE, WILLIAM (1814—1900)

pole s of which is fixed to the yoke y of a See also:

• HORSE (a word common to Teutonic languages in such forms as hors, hros, ros; cf. the Ger. ross)

horse-See also:

• SHOE (a word appearing in the Teutonic languages in various forms, as Ger. Schuh, Swed. and Dan. sko, sometimes supposed to come from an unknown root ska or sku, cover)

shoe electromagnet M . The armature is placed between the poles of the electromagnet, and being Polarized magnetized by the magnet m it will oscillate to the See also:

• POOL

Pool right or See also:

• LEFT

left under the See also:

• ACTION

action of the poles of the electro- ys. magnet M according as the current passes through M in one direction or the other . This form of relay is largely used, but in See also:

• GREAT

Great See also:

• BRITAIN (Gr. Hperavuml vi7vot, Bperravia; Lat. Britannia, rarely Britannia)

Britain it has been entirely displaced by the form shown in fig . 20, which is the most See also:

• MODERN

modern See also:

• PATTERN

pattern of relay used by the See also:

• BRITISH

British See also:

• POST

Post See also:

• OFFICE (from Lat. officium, " duty," " service," a shortened form of opifacium, from facere, " to do," and either the stem of opes, " wealth," " aid," or opus, " work ")

Office, known as the " Post Office See also:

• STANDARD
• STANDARD, BATTLE OF THE

Standard Relay." In this instrument there are two soft See also:

• IRON [symbol Fe, atomic weight 55.85 (0=16)]

iron See also:

• TONGUES, GIFT OF, or GLOSSOLALIA (yXwova, tongue, aXeiv, speak)

tongues, n, s, fixed upon and at right angles to an See also:

• AXLE (in Mid. Eng. axel-tre, from O. Norweg. oxull-tre, cognate with the O. Eng. exe or eaxe, and connected with Sansk. dksha, Gr. a wv, and Lat. axis)

axle a, which See also:

• WORKS

works on pivots at its ends . These tongues are magnetized by the inducing action of a strong horse-shoe permanent magnet, S N, which is made in a curved shape for the See also:

• SAKE

sake of compactness . The See also:

• TONGUE (O. Eng. lunge)

tongue plays between the poles of two straight electromagnets . The coils of the electromagnets are differentially See also:

• WOUND (O. Eng. wund,connected with a Teutonic verb, meaning to strive, fight, suffer, seen in O. Eng. winnan, whence Eng. " win ")

wound with See also:

• SILK

silk-covered wire, 4 mils ( = "004 See also:

• INCH (O. Eng. ynce from Lat. uncia, a twelfthpart; cf. " ounce," and see As)

inch) in See also:

• DIAMETER (from the Cr. &a, through, µErpov, measure)

diameter, to a See also:

• TOTAL

total resistance of 400 ohms . This See also:

• DIFFERENTIAL

differential winding enables the instrument to be used for " duplex " working, but the connexions of the wires to the terminal screws are such that the relay can be used for ordinary single working . Although • the relay is a " polarized " one, so that it can be used for " double-current' working, it is equally suitable for " single-current " purposes, as the tongue can be given a See also:

• BIAS
• BIAS (from the Fr. biais, of unknown origin; the derivation from Lat. bifax, two-faced, is wrong)

bias over to the " spacing " See also:

• SIDE
• SIDE (mod. Eski Adalia)

side, i.e. to 8 Iii(---- the side on which no current passes through the local circuit .

The standard relay will work single current with a current of 3 milliamperes, though in practice about io would be used . Worked double current—that is, with the tongue set neutral, having no bias either to the spacing or marking side—the relay will give See also:

• GOOD, JOHN MASON (1764-1827)

good signals with I2 milliampere of current, though in practice 10 milliamperes are provided . The lightness of the moving See also:

• PART

part enables great rapidity of action to be obtained, which for fast See also:

• SPEED, JOHN (1552–1629)

speed working is very essential . The relay tongue, being perfectly free to move, can be actuated by a comparatively weak current . Normally a switch attached to the key cuts the battery off, and connects the line direct through the receiving relay; this switch is turned to " send " when transmission commences, and is moved back to " receive " when it ceases: this See also:

• MOVEMENT

movement is done quite mechanically by the telegraphist, and as it is practically never forgotten, automatic devices (which have often been suggested) to effect the turning are wholly unnecessary . Fig . 21 shows the general arrangement of the connexions for double-current working; the See also:

• GALVANOMETER

galvanometer G is used for the purpose of th h e, current a " polarized relay " (fig . 20) with a bias is used, but on system. all important lines worked by sounders the " double- current " system is employed . In this the tongue of the relay is kept over to the spacing side by means of a current flowing in one direction, but on the depression of the signalling key the cur-See also:

• RENT

rent is reversed, moving the relay tongue over to the marking side . Standard Relay . indicating whether a station is calling, in case the relay sticks or is out of See also:

• ADJUSTMENT (from late Lat. ad juxtare, derived from juxta, near, but early confounded with a supposed derivation from justus, right)

adjustment . The key K (shown in general See also:

• PLAN
• PLAN (from Lat. planes, flat)

plan), when worked, sends reversed currents from the battery B .

In cases where " universal battery " working, i.e. the working of several instruments from one set of batteries or accumulators, is adopted, the See also:

• POSITIVE (or PORTABLE) ORGAN

positive and negative currents have to be sent from See also:

• INDEPENDENT

independent batteries, as shown by fig . 22 . The stop a of the key K is connected through a switch S with one pole of the battery B, and the stop b in the usual way with the other pole . Suppose the See also:

• ARM (a common Teutonic word; the Indo-European root is ar, to join or fit; cf. the Lat. armus, shoulder, and the plural word arma, weapons, Gr. apphs, joint, and the reduplicated apapilKSV, to join)

arm c of the switch S to be in contact with 2; then when the key is manipulated it sends alternately positive and negative currents into the line . If the positive is called the signalling current, the line will be charged positively each See also:

• TIME (0. Eng. Lima, cf. Icel. timi, Swed. timme, hour, Dan. time; from the root also seen in " tide," properly the time of between the flow and ebb of the sea, cf. O. Eng. getidan, to happen, " even-tide," &c.; it is not directly related to Lat. tempus)
• TIME, MEASUREMENT OF
• TIME, STANDARD

time a signal is sent; but as soon as the signal is completed a negative See also:

• CHARGE
• CHARGE (through the Fr. from the Late Lat. carricare, to load in a carrus or wagon; cf. " cargo ")

charge is communicated to the line, thus hastening the See also:

• DISCHARGE (adapted from the O. Fr. discharge, modern decharge, from a med. Lat. discargare, to unload, dis- and earn care, to load, cf. " charge ")

discharge and the return of the relay tongue to its insulated stop . When a local instrument such as a sounder (fig . 15) is worked from a relay, the dying away of the See also:

• MAGNETISM
• MAGNETISM, TERRESTRIAL

magnetism in the iron cores of the electromagnet, when the relay tongue moves from the Spark marking to the spacing side, i.e. when the local battery is coils• cut off, sets up an induced current of high tension, which causes a spark to jump across the contact points of the relay, and by oxidizing them makes it necessary for them to be frequently cleaned . In order to avoid this sparking, every local instrument in the British Postal See also:

• TELEGRAPH (Gr. Tike, far, and rypaq5eiv, to write)

Telegraph See also:

• DEPARTMENT (Fr. departement, from departir, to separate into parts)

Department has a " spark " coil connected across the terminals of the electromagnet . The spark coil has a resistance about ten times as great as that of the electromagnet it shunts, and the wire of which it is composed is double wound so as to have no retarding effect on the induced current, which circulates through the spark coil instead of See also:

• JUMPING

jumping in the form of a spark across the contact points . The See also:

• DEVICE

device is a most effectual one . On long circuits wcrked by the See also:

• WHEATSTONE, SIR CHARLES (1802–1875)

Wheatstone fast-speed apparatus, and especially on those in which a submarine See also:

• CABLE (from Late Lat. capulum, a halter, from capere, to take hold of)
• CABLE, GEORGE WASHINGTON (1844– )

cable is included, it Repeaters. is found necessary to introduce " repeaters " half-way, in order to enable a high speed to be maintained . The speed at which a circuit can be worked depends upon what is known as the " KR " of the line, i.e. the product of the total capacity and the total resistance, both the capacity and the resistance having a retarding effect on the signals .

By dividing a line into two halves the working speed will be dependent upon the KR of the longest half, and as both K and R are directly proportional to the length of the line, the KR product for the half of a circuit is but one See also:

• QUARTER (through Fr. from Lat. quartarius, fourth part)

quarter that of the whole length of the circuit, and the retardation is correspondingly small . Thus the speed on a line at which the repeater is situated exactly midway will be four times that of the line worked direct . Repeaters (or translators, as they are some-times termed) are in Great Britain only used on fast-speed circuits; they are in no case found necessary on circuits worked by See also:

• HAND
• HAND (a word common to Teutonic languages; cf. Ger. Hand, Goth. handus)
• HAND, FERDINAND GOTTHELF (1786-185r)

hand. or at " key speed " as it is called . Duplex telegraphy consists in the simultaneous transmission of two messages, one in each direction, over the same wire . The See also:

• SOLUTION (from Lat. solvere, to loosen, dissolve)

solution of this problem was attempted by J . W . Gintl of See also:

• VIENNA (Ger. Wien; Lat. Vindobona)
• VIENNA, CONGRESS OF (1814-1815)

Vienna in 1853 and in the following See also:

• YEAR

year by Frischen and by Siemens and Halske . Within a few years several methods had been proposed by different inventors, but none was at first very successful, not from any See also:

• FAULT (Mid. Eng. faute, through the French, from the popular Latin use of fallere, to fail; the originallof the Latin being replaced in English in the 15th century)

fault in the principle, but because the effect of electrostatic capacity of the line was left out of See also:

• ACCOUNT
• ACCOUNT (through O. Fr. acont, Late Lat. comptum, cornputare, to calculate)

account in the See also:

• EARLY
• EARLY, JUBAL ANDERSON (1816-1894)

early arrangements . The first to introduce a really good See also:

• PRACTICAL

practical system of duplex telegraphy, in which this difficulty was sufficiently overcome for See also:

• LAND

land line purposes, was J . B . Stearns of See also:

• BOSTON
• BOSTON, THOMAS (1676-1732)

Boston (See also:

• MASS (O.E. maesse; Fr. messe; Ger. Messe; Ital. messa; from eccl. Lat. missa)
• MASS, IN

Mass.) . In order that the line between two stations may be worked on the duplex system it is essential that the receiving instrument shall not be acted on by the outgoing currents, but shall See also:

• RESPOND

respond to incoming currents .

The two methods most commonly employed are the differential and See also:

• BRIDGE

bridge methods . In fig . 23, representing the " differential " metjhod, B is the sending battery, Bl a resistance equal to that of the battery, R a rheostat and C an adjustable See also:

• CONDENSER

condenser . Suppose the Differ-winding to be depressed, then a current flows through one Differ-winding of the differential relay to line and through the method. other winding and rheostat to earth . Now if the values of the rheostat and condenser are adjusted so as to make the rise and fall of the outgoing current through both windings of the relay exactly equal, then no effect is produced on the armature of the relay, as the two currents neutralize each other's magnetizing effect . Incoming currents pass from line through one coil of the relay, the key, and either the battery or battery resistance, according as whether the key is raised or depressed . The result is that the armature of the relay is attracted, and currents are sent through the sounder from the local battery, producing the signals from the distant station . When the key is in the See also:

• MIDDLE

middle position, that is, not making connexion with either the front or back contacts, the received currents pass through both coils of the relay and the rheostat; no interference is, however, See also:

• FELT (cognate with Ger. Filz, Du. vilt, Swed. and Dan. fill; the root is unknown; the word has given Med. Lat. filtrum, " filter ")

felt from this extra resistance because, although the current is halved, it has double the effect on the relay, because it passes through two coils instead of one . Line Earth In the " bridge " method (fig . 24), instead of sending the currents through the two coils of a differentially wound relay or receiving instrument as in Frischen's method, two resistances a and b are inserted, and the receiving instrument is joined between P and Q . The currents thus See also:

• DIVIDE

divide at the point D, and it is clear that if the difference of potential between P and Q is unaffected by closing the sending key, then no See also:

• CHANGE (derived through the Fr. from the Late Lat. cambium, cambiare, to barter; the ultimate derivation is probably from the root which appears in the Gr. «a urmu', to bend)

change of current will take See also:

• PLACE (through Fr. from Lat. platea, street; Gr. IrAar6s, wide)

place in the instrument circuit . The P Line Receiving Instrument R -IIIIIIilIl relative potential of P and Q is not affected by the manipulation of the sending key if the resistance of a bears the same proportion to that of b as the resistance of the line does to that of the resistance R; hence that is the arrangement used .

One very great See also:

• ADVANTAGE

advantage in this method is that the instrument used between P and Q may be of any ordinary form, i.e. relay, See also:

• HUGHES, DAVID EDWARD (1831-1900)
• HUGHES, HUGH PRICE (1847-19o2)
• HUGHES, JOHN (1677-1720)
• HUGHES, JOHN (1797-1864)
• HUGHES, SIR EDWARD (c. 1720-1794)
• HUGHES, THOMAS
• HUGHES, THOMAS (1822-1896)

Hughes, See also:

• SIPHON, or SYPHON (Lat. sipho; Gr. vi4xov, a tube)

siphon re-corder, &c . Most important cables, such as those of the Eastern Telegraph See also:

• COMPANY

Company and the various See also:

• ATLANTIC

Atlantic cables, are worked duplex on Muirhead's plan . What may be called a See also:

• MECHANICAL

mechanical method of duplexing a cable was described by See also:

• LORD
• LORD (O. Eng. hldford, i.e. hldfweard, the warder or keeper of bread, hlIf, loaf; the word is not represented in any other Teutonic language)
• LORD, JOHN (1810-1894)

Lord Duplex See also:

• KELVIN, WILLIAM THOMSON, BARON (1824-1907)

Kelvin in a patent taken out by him in 1858 . In this, as working in the ordinary methods, a differentially wound receiving oncahieS. instrument was used, one coil being connected with the cable and the other with the earth; but it differed from other methods in requiring no " artificial " or balancing cable . The See also:

• COMPENSATION (from Lat. compensare, to weigh one thing against another)

compensation was to be obtained by working a slide resistance included in the circuit of the compensating coil, either by the sending key or by clockwork released by the key, so as to vary the resistance in that Duplex telegraphy . Bridge method . circuit according to any See also:

• LAW
• LAW (0. Eng. lagu, M. Eng. lawe; from an old Teutonic root lag, " lie," what lies fixed or evenly; cf. Lat. lex, Fr. loi)
• LAW, JOHN (1671—1729)
• LAW, WILLIAM (1686-1761)

law which might be required to prevent the receiving instrument being affected by the outgoing current . Four years later See also:

• VARLEY, CORNELIUS (1781-1873)
• VARLEY, JOHN (1778-1842)

Varley patented his artificial cable, which was the first near approach to a successful solution of the duplex problem on the principle now adopted . It was not, however, a sufficiently perfect See also:

• REPRESENTATION

representation of a laid cable to serve for duplexing cables of more than a few See also:

• HUNDRED

hundred See also:

• MILES, NELSON APPLETON (1839— )

miles in length . By a modification of the bridge method, applied with excellent results by Dr Muirhead to submarine work, condensers are substituted for a and b, one being also placed in the circuit between P and Q . In this case no current flows from the battery through the line or instruments, the whole action being inductive . As we have already stated, the See also:

• DISTRIBUTION (Lat. distribuere, to deal out)

distribution of the capacity along the resistance R must in submarine cable work be made to correspond very accurately with the distribution of the capacity along the resistance of the cable .

This is accomplished by Dr Muirhead in the following manner . One side of a See also:

• SHEET

sheet of paraffined See also:

• PAPER
• PAPER (Fr. papier, from Lat. papyrus)

paper is covered with a sheet of conducting substance, say tinfoil, and over the other side narrow strips of the same substance are arranged gridironwise to form a continuous circuit along the See also:

• STRIP

strip . The breadth and thickness of the strip and the thickness of the paraffined paper are adjusted so that the relative resistance and capacity of this arrangement are the same as those of the cable with which it is intended to be used . A large number of such sheets are prepared and placed together, one over the other, the end of the strip of the first sheet being connected with the beginning of the strip of the second, and so on to the last sheet, the whole representing the conductor of the cable . In the same way all the conducting sheets on the other side of the paper are connected together and form the earth-See also:

• PLATE

plate of this artificial cable, thus representing the See also:

• SEA (in O. Eng. sae, a common Teutonic word; cf. Ger. See, Dutch Zee, &c.; the ultimate source is uncertain)
• SEA, COMMAND OF THE

sea . The leakage through the insulator of the cable is compensated for by connecting high resistances between different points of the strip conductor and the earth coating . Faults or any other irregularity in the cable may be represented by putting resistances of the proper See also:

• KIND (O. E. ge-cynde, from the same root as is seen in " kin," supra)

kind into the artificial line . This system of duplexing cables has proved remarkably successful . Quadruplex telegraphy consists in the simultaneous trans-See also:

• MISSION

mission of two messages from each end of the line . The only new problem introduced is the simultaneous transmission of Quad- two messages in the same direction; this is sometimes ruplex called " diplex transmission." The solution of this tele- problem was attempted by Dr J . B . See also:

• STARK, JAMES (1794-1859)
• STARK, JOHN (1728-1822)

Stark of Vienna graphy. in 1855, and during the next ten years it was worked at by Bosscha, Kramer, Maron, Schaak, Schreder, Wartmann and others .

The first to attain practical success was See also:

• EDISON, THOMAS ALVA (1847– )

Edison, and his method with some modifications is still the one in most general use . The arrangement is shown in fig . 25, and indicates the general principle involved . Kl and K2 are two transmitting keys; the former reverses the direction of the line current, the latter increases the strength irrespective of direction, by joining on another battery when the key is depressed . RI and See also:

• R2(rt-s2)

R2 are relays for receiving the currents; the former is polarized and .responds to reversals of current, while the latter is non-polarized and responds only to the increased current from K2 irrespective of the direction of that current . This arrangement can be duplexed in the way already explained, by providing differential relays and arranging for the outgoing currents to divide differentially through the two relays at each end . The " multiplex " system devised by See also:

• PATRICK, SIMON (1626–1707)
• PATRICK, ST

Patrick B . See also:

• DELANY, MARY GRANVILLE (1700-1788)

Delany (which was adopted to a limited extent in Great Britain, but has now been entirely discarded) had for its See also:

• OBJECT

object the working of a num- ber of instruments simultaneously on one wire . The general principle of the arrangement of the apparatus is shown by fig . 26 . Arms a and b, one at each station A and B, are connected to the line wire, and are made to rotate simultaneously over metallic segments, I, 2, 3, 4, and i', 2', 3', 4', at the two stations, so that when the arm a is on segment I at A, then b is on segment 1' at B, and so on . At each station sets of telegraph apparatus are connected to the segments, so that when the arms are kept rotating the set connected to I becomes periodically See also:

• CON

con- nected to the set connected to 1', the set connected to 2 to the set connected to 2', and so on .

In practice the number of segments actually employed is much greater than that indicated on the figure, and the segments are arranged in a number of See also:

• GROUPS
• GROUPS, THEORY

groups, as shown by fig . 27, all the segments i being connected together, all the segments 2, all the segments 3, and all the segments 4 . To each See also:

• GROUP

group is connected a set of apparatus; hence during a See also:

• COMPLETE

complete revolution of the arms a pair of instruments (at station A and station B) will be in communication four times, and the intervals during which any particular set of instruments at the two stations are not in connexion with each other become much smaller than in the case of fig . 26 . In practice this subdivision of the segments is so far extended that the intervals of disconnexion become extremely A B 2 -~ t' tine small, and each set of apparatus works as if it were alone connected to the line . As many as 162 segments in eight groups are practically used . The arm which moves See also:

• ROUND (O. Fr. rond, Lat. rotundus, the Fr. is the source also of Du. rond; Ger., Swed., Dan. and Nor. rond)

round over the segments rotates at the See also:

• RATE

rate of three revolutions per second, and is kept in See also:

• MOTION (Lat. motio, from movere, to move)
• MOTION, LAWS OF

motion by means of an iron toothed See also:

• WHEEL (0. Eng. hweol, hweohl, &c., cognate with Icel. hjol, Dan. hiul, the Indo-European root is seen in Sanskrit chakra, Gr. r in Aos, circle, whence " cycle ")
• WHEEL, BREAKING ON THE

wheel, the rim of which is set in close proximity to the poles of an electromagnet . Through this electromagnet pass impulses of current regulated in frequency by a tuning-See also:

• FORK (Lat. furca)

fork contact breaker; these impulses, acting on the See also:

• TEETH (O.E. Eel); plural of tooth, O.E. top)

teeth of the iron wheel, by a See also:

• SERIES (a Latin word from serere, to join)

series of pulls keep it in See also:

• UNIFORM

uniform rotation . If the rates of vibration of the two tuning-forks at the two stations could be maintained precisely the same, the two arms would rotate in synchronism, but as this uniform vibration cannot be exactly A B / 4~ t + . 3/ .fl 1 3j 2 1 Line Cl ~ 2 4 / 2 3 4 --I . retard the rate of rotation of one or other of the arms . This is effected by means of " correcting " segments, of which there are six sets containing three each .

Should the rotating arms fail to pass over these correcting segments at their synchronous positions, correcting currents pass to a relay which cuts off momentarily the current actuating the tuning-fork, thereby altering the rate of vibration of the latter until the arms once more run together uniformly . The actual number of sets of apparatus it was possible to work multiplex depended upon the length of the line, for if the latter were long, retardation effects modified the working conditions . Thus between See also:

• LONDON

London and See also:

• MANCHESTER
• MANCHESTER (popularly Manchester-by-the-Sea)
• MANCHESTER, EARLS AND DUKES OF

Manchester only four sets of apparatus could be worked, but between London..and See also:

• BIRMINGHAM

Birmingham, a shorter distance, six sets (the maximum for wl ich the system is adapted) were used . Chemical Telegraphs.—A method of recording signals in the See also:

• MORSE, SAMUEL FINLEY BREESE (1791—1872)

Morse code, formerly used to a considerable extent, was to use a chemically prepared ribbon of paper . Suppose, for instance, the paper ribbon to be soaked in a solution of iodide of See also:

• POTASSIUM [symbol K (from kalium), atomic weight 39.114 0=16)]

potassium and a See also:

• LIGHT

light contact spring made to See also:

• PRESS (through Fr. presse from Lat. pressare, frequentative of premere, to crush, squeeze, press)

press continuously on its See also:

• SURFACE

surface as it is pulled forward by the mechanism . Then, if a current is sent from the spring to the See also:

• ROLLER

roller through the paper, a See also:

• BROWN
• BROWN, CHARLES BROCKDEN (1771-181o)
• BROWN, FORD MADOX (1821-1893)
• BROWN, FRANCIS (1849- )
• BROWN, GEORGE (1818-188o)
• BROWN, HENRY KIRKE (1814-1886)
• BROWN, JACOB (1775–1828)
• BROWN, JOHN (1715–1766)
• BROWN, JOHN (1722-1787)
• BROWN, JOHN (1735–1788)
• BROWN, JOHN (1784–1858)
• BROWN, JOHN (1800-1859)
• BROWN, JOHN (1810—1882)
• BROWN, JOHN GEORGE (1831— )
• BROWN, ROBERT (1773-1858)
• BROWN, SAMUEL MORISON (1817—1856)
• BROWN, SIR GEORGE (1790-1865)
• BROWN, SIR JOHN (1816-1896)
• BROWN, SIR WILLIAM, BART
• BROWN, THOMAS (1663-1704)
• BROWN, THOMAS (1778-1820)
• BROWN, THOMAS EDWARD (1830-1897)
• BROWN, WILLIAM LAURENCE (1755–1830)

brown See also:

• MARK
• MARK, CARL (1858– )
• MARK, GOSPEL OF ST
• MARK, ST

mark will be made by the spring due to the liberation of See also:

• IODINE (symbol I, atomic weight '26.92)

iodine . This was the principle of the chemical telegraph proposed by See also:

• EDWARD

Edward See also:

• DAVY, SIR HUMPHRY

Davy in 1838 and of that proposed by See also:

• BAIN, ALEXANDER (1818-1903)
• BAIN, ANDREW GEDDES (1797-1864)

Bain in 1846 . Several ingenious applications of his method were proposed and practically worked, as, for example, the copying telegraph of See also:

• BAKEWELL
• BAKEWELL, ROBERT (1725-1795)
• BAKEWELL, ROBERT (1768–1843)

Bakewell and of Cros, by means of which a telegram may be transmitted in the sender's own See also:

• HANDWRITING

handwriting; the pantelegraph of Caselli; the auto-graphic telegraphs of See also:

• MEYER, CHRISTIAN ERICH HERMANN VON (18or-1869)
• MEYER, HEINRICH AUGUST WILHELM (1800-1873)
• MEYER, JULIUS LOTHAR (183o-1895)
• MEYER, KONRAD FERDINAND (1825-1898)
• MEYER, VICTOR (1848-1897)
• MEYER, [MARIE] PAUL HYACINTHE (184o- )

Meyer, Lenoir, See also:

• SAWYER, SIR ROBERT (1633-1692)

Sawyer and others; and the autographic typo-telegraph of Bonelli; all forms of the apparatus have, however, fallen into disuse . Automatic Telegraphs.—It was found impossible to make the Morse See also:

• INK (from Late Lat. encaustum, Gr. gysavorov, the purple ink used by Greek and Roman emperors, from iyKaiew, to burn in)

ink writer so sensitive that it could See also:

• RECORD (Lat. recordari, to recall to mind, from cor, heart or mind)

record signals sent over land lines of several hundred miles in length, if the speed of transmission was very much faster than that which could be effected by hand, and this led to the See also:

• ADOPTION (Lat. adoptio, for adoptalio, from adoptare, to choose for oneself)

adoption of automatic methods of transmission . One was proposed by Bain as early as 1846, but it did not come into use . That now employed is, however, practically a development of his Multiplex telegraphy . See also:

• IDEA (Gr. Ibia, connected with i&eiv, to see; cf. Lat. species from specere, to look at)

idea .

It consists in punching, by means of " a puncher," a series of holes in a strip of paper in such a way that, when the strip is sent through another instrument, called the " transmitter," the holes cause the circuit to be closed at the proper times and for the proper proportionate intervals for the See also:

• MESSAGE (a word occurring in slightly different forms in several languages, e.g. Fr. message, Span. mensaje, Ital. messagio; adapted from the Low Lat. missaticum, from mittere)

message to be correctly printed by the receiving instrument or See also:

• RECORDER
• RECORDER, FIPPLE FLUTE

recorder . The most successful apparatus of this kind is that devised by \Vheatstone; others were devised by Siemens and Halske, See also:

• GARNIER, CLEMENT JOSEPH (1813–1881)
• GARNIER, GERMAIN, MARQUIS (1754-1821)
• GARNIER, JEAN LOUIS CHARLES (1825-1898)
• GARNIER, MARIE JOSEPH FRANCOIS [FRANCIS] (1839–1873)
• GARNIER, ROBERT (c. 1545–c.1600)

Garnier, Humaston, Siemens, and Little . In the Wheatstone automatic apparatus three levers are placed side by side, each acting on a set of small punches and See also:

• WHEAT
• WHEAT (Triticum)

wheat- on mechanism for feeding the paper forward a step See also:

• STONE
• STONE (0. Eng. shin; the word is common to Teutonic languages, cf. Ger. Stein, Du. steen, Dan. and Swed. sten; the root is also seen in Gr. aria, pebble)
• STONE, CHARLES POMEROY (1824-1887)
• STONE, EDWARD JAMES (1831-1897)
• STONE, FRANK (1800-1859)
• STONE, GEORGE (1708—1764)
• STONE, LUCY [BLACKWELL] (1818-1893)
• STONE, MARCUS (184o— )
• STONE, NICHOLAS (1586-1647)

stone after each operation of the levers . The punches are system. arranged as shown in fig . 28, and the levers are adjusted so that the left-hand one moves a, b, c and punches a See also:

• ROW, JOHN (c. 1525—1580)

row of holes across the paper (group r in the figure), the middle one moves b only and punches a centre hole (2 in the figure), while the right-hand one moves a, b, d, e and punches O4' Ob Od O' 0• Fig . 28.—Wheatstone Punching Apparatus . four holes (3 and 4 in the figure) . The whole of this operation represents a dot and a dash or the See also:

• LETTER (through Fr. lettre from Lat. littera or litera, letter of the alphabet; the origin of the Latin word is obscure; it has probably no connexion with the root of linere, to smear, i.e. with wax, for an inscription with a stilus)

letter " a." The side rows of holes only are used for transmitting the message, the centre row being required for feeding forward the paper in the transmitter . The perforation of the paper when done by hand is usually performed by means of small mallets, but at the central telegraph office in London, and at other large offices, the keys are only used for opening See also:

• AIR (from an Indo-European root meaning " breathe," " blow ")
• AIR, or ASBEN

air-valves, the actual punching being done by pneumatic pressure . In this way several thicknesses of paper can be perforated at the same time, which is a great convenience for press work, since copies of the same message have often to be transmitted to several See also:

• NEWSPAPERS

newspapers at the same time . The mode of using the paper ribbon for the transmission of the message is illustrated in fig . 29 .

An ebonite See also:

• BEAM
• BEAM (from the O. Eng. beam, cf. Ger. Baum, a tree, to which sense may be referred the use of " beam " as meaning the rood or crucifix, and the survival in certain names of trees, as horn-beam)

beam B is rocked up and down rapidly by a See also:

• TRAIN (M. Eng. trayn or trayne, derived through Fr. from Late Lat. trahinare, to drag, draw, Lat. trahere, cf. trail, trace, ultimately from the same source)

train of mechanism, and moves the cranks A and A' by means of two See also:

• METAL
• METAL (through Fr. from Lat. metallum, mine, quarry, adapted from Gr. µATaXAov, in the same sense, probably connected with ,ueraAAdv, to search after, explore, µeTa, after, aAAos, other)

metal pins P, P' . A and A' carry two light See also:

• VERTICAL (from Lat. vertex, highest point)

vertical rods S, M, the one as much in front of the other as there is space between two successive holes in the perforated ribbon . To the other ends of A, A', rods H, H' are loosely hinged, their ends passing loosely through holes in the end of the bar L . By means of two collars K, K', the lever L is made to oscillate in unison with the beam B . The operation is as follows : the paper ribbon or perforated slip is moved forward by its centre row of holes at the proper speed above the upper ends of the rods S, M ; should there be no holes in the ribbon then the cranks A, A' will remain stationary, although the beam B continues to See also:

• ROCK
• ROCK (O.Fr. rake, Sp. rota, Ital. rocca; possibly from a Lat. form rupica, from rupes, rock)
• ROCK, DANIEL (1799–187t)

rock, since the rods S, M are pressing- against the ribbon and cannot rise . Should, however, a row of holes, like group t, fig . 28, be in the ribbon, the See also:

• ROD (O.E. rodd, probably related to Norw. rudda, stick, rodda, stake)
• ROD, EDOUARD (1857-1910)

rod M will first be allowed to pass through the paper, and the corresponding movement of See also:

• CRANK

crank A' will, through the agency of collet K, throw over lever L, and the battery See also:

• ZINC

zinc will be put to the line; at the next half stroke of the beam, S will pass through, and crank A by its movement will, through the agency of collet K', throw over lever L in the See also:

• REVERSE

reverse direction, so that the battery See also:

• COPPER (symbol Cu, atomic weight 63.1, H=1, or 63.6, O = 16)

copper will be put to the line . Thus for a dot, first a negative and then a positive current is sent to the line, the effect of the current continuing during the time required for the paper to travel the space between two holes . Again, suppose groups 3 and 4 to be punched . The first part will be, as before, zinc to the line; at the next half stroke of the beam M will not pass through, as there is no hole in the paper; but at the third half stroke it passes through and copper is put to the line . Thus for a dash the See also:

• INTERVAL

interval between the positive and the negative current is equal to the time the paper takes to travel over twice the space between two successive holes . Hence for sending both a dot and a dash, reverse currents of short duration are sent through the line, but the interval between the reversal is three times as great for the dash as for the dot .

In the receiving instrument the electromagnet is constructed in precisely a similar way to the relay (fig . 20), so that the armature, if pulled into any position by either current, remains in that position, whether the current continues to flow or not, until a reverse current is made to See also:

• ACT (Lat. actus, actum)

act on the magnet . For the dot the armature is deflected by the first current, the ink-wheel being brought into contact with the paper and after a short interval pulled back by the reverse current . In the case of the dash the ink-wheel is brought into contact with the paper by the first current as before and is pulled back by the reverse current after three times the interval . The armature acts on an inking disk on the principle described above, See also:

• SAVE, or SAVA (Ger. Sau; Hungarian Szdva; Lat. Savus)

save only that the disk is supplied with ink from a groove in a second wheel, on which it rolls: the grooved wheel is kept turning with one edge in contact with ink in an ink-well . By this method of transmission the battery is always to the line for the same interval of time, and alternately with opposite poles, so that the effect of electrostatic See also:

• INDUCTION (from Lat. inducere, to lead into; cf. Gr. ilrayu yli)

induction is reduced to a minimum . Although it is quite possible to obtain good signals at a rate corresponding to 600 letters per See also:

• MINUTE
• MINUTE (Lat. minutes, small; minuere, to make less)

minute, in practice it is found that such a high speed is not advisable, as it is difficult or impossible for even the most skilled operators properly to handle and transcribe from the " slip" on which the signals are recorded . In Squier and Crehore's " Synchronograph " system " sine waves " of current, instead of See also:

• SHARP, GRANVILLE (1735-1813)
• SHARP, JAMES (1618-1679)
• SHARP, JOHN (1645-1714)
• SHARP, RICHARD (1759-1835)
• SHARP, WILLIAM (1749-1824)
• SHARP, WILLIAM (1856-1905)

sharp " makes and breaks," or sharp reversals, are employed for transmitting signals, the waves being Squlerand produced by an alternating-current See also:

• DYNAMO (a shortened form of " dynamo-electric machine," from Gr. Sbvaµis, power)

dynamo, and regu- Grehore lated by means of a perforated paper ribbon, as in the system . Wheatstone automatic system . The arrangement has been found under certain conditions to give better results than those obtained with sharp reversals . In the undulator apparatus, which is similar in general principle to the " siphon recorder " used in submarine telegraphy, a spring or falling See also:

• WEIGHT

weight moves a paper strip beneath one end of The un- a See also:

• FINE

fine See also:

• SILVER

silver See also:

• TUBE (Lat. tuba)

tube, the other end of which dips into a dulator. See also:

• VESSEL (O. Fr. vaissel, from a rare Lat. vascellum, dim. of vas, vase, urn)

vessel containing ink . The siphon is supported on a vertical axle carrying two armatures which are acted upon by two electromagnets .

It is in fact the electromagnet and spindle of a telegraph relay with a siphon in place of the tongue . See also:

• SCREW (O.E. scrue, from O. Fr. escroue, mod. ecrou; ultimate origin uncertain; the word, or a similar one, appears in Teutonic languages, cf. Ger. Schraube, Dan. skrue, but Skeat, following Diaz, finds the origin in Lat. scrobs, a ditch, hole, particularl

Screw adjustments are provided for closing or opening the air See also:

• GAP

gap between the electromagnets and armatures, for raising or lowering the siphon, and for adjusting the point of the siphon to the centre or side of the paper strip . The received signals are recorded on the paper strip in an undulating continuous line of ink, and are distinguished by the length of deviation from zero . The See also:

• AMPLITUDE (from Lat. amplus, large)

amplitude of the signals can be varied in several ways, either by a shunt across the electromagnet, or by altering the tension of the controlling springs or by altering the air gap between electromagnets and armatures . Up to too words per minute the signals are easily readable, but beyond that speed they are more difficult to translate, although experts can read them when received at 20o words per minute . Pollak-Virag System.—In the improved Pollak-Virag system the received signals are recorded in characters similar to ordinary hand-See also:

• WRITING
• WRITING (the verbal noun of " to write," O. Eng. writan, to inscribe)

writing . The operator actuates a See also:

• TYPEWRITER

typewriter form of perforator which punches varying groups of holes, representing the different characters, in a paper strip about one inch wide . This slip is then passed through a transmitter fitted with See also:

• BRUSH (from Fr. brosse, which, like the English word, means both the undergrowth of a wood and the instrument; if the word in both these meanings is ultimately the same, then the origin is from a bundle of brushwood used as a brush or broom, but this is h
• BRUSH, GEORGE DE FOREST (1855– )

brush contacts and connected to the two line wires of a metallic See also:

• LOOP

loop . One circuit is formed by the loop itself, and a second, quite independent, by the two wires in parallel, earthed at each end . At the receiving end there are two See also:

• TELEPHONE (Gr. rjXs, far, and dxwvr7, voice)

telephone receivers, one joined in the loop circuit, the other in the earth return circuit . The diaphragms of these are mechanically connected to a small See also:

• MIRROR (through O. Fr. mirour, mod. miroir, from a sup-posed Late Lat. miratorium, from mirari, to admire)

mirror and See also:

• CONTROL (Fr. contrdle, older form contre rolle, from Med. Lat. contra-rotulus, a counter roll or copy of a document used to check the original; there is no instance in English of the use of " control " in this, its literal, meaning)

control its movement in accordance with the strength and direction of the received currents . One See also:

• DIAPHRAGM (Gr. Scat/pay,aa, a partition)

diaphragm gives the mirror a movement in a vertical direction while the other gives it a See also:

• HORIZONTAL

horizontal motion .

The two acting together can thus give the mirror any desired movement within limits . A See also:

• RAY (Lat. raia)
• RAY (or WRAY, as he wrote his name till 1670), JOHN (1628-1705)

ray of light is directed upon the mirror, and the motion of the latter, due to the varying strengths and direction of the received currents, is made to write the transmitted signals upon a strip of bromide photographic paper about three inches wide . The line of writing is of course continuous, there being no break, although there is a space between words . The writing, although not well formed, is sufficiently distinct for ordinary messages; the figures 3, 5, and 8 are, however, liable to be mistaken for each other, being very similar in See also:

• APPEARANCE (from Lat. apparere, to appear)

appearance . The bromide paper is automatically passed through a developing See also:

• BATH
• BATH, THOMAS THYNNE
• BATH, WILLIAM

bath, a fixing bath, and drying rollers . This operation occupies about twelve seconds, giving a message written in See also:

• COLUMN (Lat. columna)

column form ready for delivery . It is not a system likely to have general application . Type See also:

• PRINTING (from Lat. imprimere, O. Fr. empreindre)

Printing Telegraphs.—The first considerable improvement in type printing telegraphs was made by D . E . Hughes in 1855 . Hughes In the Hughes instrument two trains of clockwork iau Hughes one at each end of the line, are kept moving See also:

• MEAT

meat. at the same speed . Each instrument is provided with a See also:

• KEYBOARD, or MANUAL (Fr. clavier; Ger. Klaviatur; Ital. tastatura)

keyboard, resembling that of a small piano, the key levers of which communicate with a circular row of vertical pins .

A horizontal arm fixed to a vertical See also:

• SHAFT
• SHAFT (O. Eng., sceaft, from scafan, to shave; the word is common to Teutonic languages)

shaft in See also:

• GEAR (connected with " garb," properly elegance, fashion, especially of dress, and with " gar," to cause to do, only found in Scottish and northern dialects; the root of the word is seen in the Old Tent. garwjan, to make ready)

gear with the mechanism sweeps over these pins at the rate of about two revolutions per second . When a key is depressed, slightly raising one of the pins, the horizontal arm will pass over it and in doing so will momentarily join the battery to the line . The current thus sent to the line may be made either to act directly on the printing instrument or to close a local circuit by means of a relay For simplicity we will suppose direct action . The current then passes through the coils of an electromagnet, which releases the printing mechanism . The electromagnet consists of two coils, each wound on a soft iron core fixed to the poles of a strong permanent horse-shoe magnet . The armature of the electromagnet is normally attracted by the effect of the permanent magnet, but it is furnished with two antagonistic springs tending to throw it upwards . These springs are so adjusted that they are not quite "able to See also:

• RELEASE (O.Fr. reles, variant of relais, from relaisser, to release, let go, Lat. relaxare)

release the armature . When a current comes in from line it passes through the electromagnet in such a direction as to weaken the effect of the permanent magnet; hence the springs are able to release the armature, which rises smartly and in its turn releases the printing mechanism . Either a weight or a motor is used for making the movements of the mechanism required to effect the printing of the signals . The type-wheel is carried round continuously by the mechanism to which it is attached by a See also:

• FRICTION (from Lat. fricare, to rub)

friction disk and ratchet drive . An axle carrying four cams is normally at See also:

• REST (O. Eng. rest, reste, bed, cognate with other Teutonic forms, e.g. Ger. Rast, Riiste, rest, and probably Gothic Rasta, league, i.e. resting or stopping place)

rest, but it is thrown into gear with the mechanism when the armature rises, makes one complete revolution, and comes to rest ready for the next signal . In its revolution one of its cams engages with the correcting wheel attached to the type-wheel in order to ensure that the latter is in the correct position for printing a complete letter; the second See also:

• CAM (CAO), DIOGO (fl. 1480-1486)

cam lifts the paper against the type-wheel and prints the letter; the third moves forward the paper tape one space to be ready for the printing of the next letter; and the last cam replaces the armature on the cores of the electromagnet .

This complete operation occupies about one-twelfth of a second . It is of course necessary that two instruments working together should have the same speed . This is obtained by causing one of them to send a series of signals from one particular key, while the operator at the other station adjusts his speed until he receives the same signal after short-circuiting his electromagnet for ten revolutions . Both type-wheels are then set to zero by the lever provided for that purpose, and released by the current from the letter-See also:

• BLANK (from the Fr. blanc, white)

blank key; then all subsequent signals will be recorded similarly at the sending and receiving ends . If by any See also:

• CHANCE (through the O. Fr. cheance, from the Late Lat. cadentia, things happening, from cadere, to fall out, happen; cf. " case ")

chance wrong signals are printed or the instruments get out of phase, the sender is stopped by the See also:

• RECEIVER

receiver sending a few signals, after which both type-wheels are again set to zero and See also:

• CORRESPONDENCE
• CORRESPONDENCE (from med. scholastic Lat. correspondentia, corrcspondere, compounded of Lat. cum, with, and respond ere, to answer; cf. Fr. correspondance)

correspondence continued . This system of telegraphic printing has a great advantage over the step-by-step system in avoiding the See also:

• NECESSITY (Lat. necessitas)

necessity for the rapidly acting electric escapement, which, however skilfully planned and executed, is always liable to failure when worked too rapidly . In Hughes's instrument almost perfect accuracy and certainty have been attained; and in actual practice it has proved to be decidedly See also:

• SUPERIOR

superior to all previous type-printing telegraphs, not only in speed and accuracy, but in less liability to mechanical derangement from See also:

• WEAR

wear and See also:

• TEAR

tear and from See also:

• ACCIDENT
• ACCIDENT (from Lat. accidere, to happen)

accident . It involves many novel features: the receiving electromagnet is of See also:

• PECULIAR

peculiar construction and remarkable efficiency and the transmitting apparatus has a contrivance to prevent unintentional repetitions of a letter through the operator holding his See also:

• FINGER

finger too long on a key . This instrument was for some years extensively used in the See also:

• UNITED

United States, until superseded by G . M . See also:

• PHELPS, AUSTIN (182o-1890)
• PHELPS, EDWARD JOHN (1822-I900)
• PHELPS, SAMUEL (1804-1878)

Phelps's modification of it, known as the " American See also:

• COMBINATION (Lat. combinare, to combine)

combination printing telegraph," because it embodied part of Hughes's and part of See also:

• HOUSE
• HOUSE (O. Eng. hiss, a word common to Teutonic languages, cf. Dut. huis, Ger. Haus; in Gothic it is only found in gudhiss, a temple; it may be ultimately connected with the root of " hide," conceal)

House's instruments . With this modified form somewhat greater speed was obtained, but it was found difficult to drive, requiring the use of See also:

• STEAM
• STEAM (0. Eng. steam, vapour, smoke, cf. Du. steam; the origin is unknown)

steam or some such See also:

• MOTIVE (from Lat. movere, to move)

motive-power .

In a subsequent modification introduced in 1875 an electromotor was applied to drive the printing mechanism . This allowed a shorter train and stronger wheelwork to be used, securing more certain action, and involving less See also:

• RISK

risk of derangement . Hughes's form was taken up by the See also:

• FRENCH
• FRENCH, DANIEL CHESTER (1850– )
• FRENCH, NICHOLAS (1604-1678)

French See also:

• GOVERNMENT
• GOVERNMENT (0. Fr. governement, mod. gouvernement, O. Fr. governer, mod. gouverner, from Lat. gubernare, to steer a ship, guide, rule; cf. Gr. xv(3epvav)

government in 1860, and is very largely in use not only in See also:

• FRANCE
• FRANCE, ANATOLE (1844– )

France but in all See also:

• EUROPEAN

European countries, including Great Britain . The system brought out in 1874 by Emile Baudot and since considerably See also:

• DEVELOPED

developed is a multiplex system giving from two to Baudot six channels on one wire, each channel giving a working system. speed of thirt y words per minute . The channels can be worked in either direction according to the traffic requirements . The line is joined at each end to distributors which are arranged to maintain uniform speed and to control their respective receivers . Each channel consists of a keyboard and receiver both electrically connected to certain parts of the distributor . The keyboard has five keys similar to those of a piano, and the letters and figures are obtained by the different combinations which can be formed by the raised and depressed keys . In the raised position a negative battery is connected to the distributor and in the de-pressed position a positive battery . At See also:

• REGULAR

regular intervals a rotating arm on the distributor connects the five keys of each keyboard to line, thus passing the signals to the distant station, where they pass through the distributor and certain relays which repeat the currents corresponding to the depressed keys and actuate electromagnets in the receivers . Each receiver is provided with five electromagnets corresponding to the five keys of the keyboard, and the armatures of the electromagnets can thus repeat the various combinations for all the signals allocated to the different combinations of the keys . When a combination of signals has been received and the armatures have taken up their respective positions corresponding to the transmitting keyboard, certain mechanism in the receiver translates the position of the five armatures into a mechanical movement which lifts the paper tape against a type-wheel and prints the corresponding letter .

The movement for any particular combination of armatures can only take place once per revolution of the type-wheel and at one particular place . The signals must therefore be sent at regular intervals, and to ensure this being done correctly a telephone or time-tapper is provided at each key-See also:

• BOARD (O. Eng. bord)

board to warn the operator of the correct moment to depress his keys . The Baudot apparatus can have certain channels extended so as to form a means of continuous communication between one station and two or three others by means of one line . It can also be duplexed or repeated similar to any other telegraph system . In the See also:

• MURRAY
• MURRAY (or MORAY), EARLS OF
• MURRAY (or MORAY), JAMES STUART, EARL OF (c. 1531-1570)
• MURRAY (or MORAY), SIR ROBERT (c. 1600-1673)
• MURRAY, ALEXANDER STUART (1841-1904)
• MURRAY, DAVID (1849– )
• MURRAY, EUSTACE CLARE GRENVILLE (1824–1881)
• MURRAY, JAMES (c. 1719-1794)
• MURRAY, JOHN
• MURRAY, JOHN (1778–1820)
• MURRAY, LINDLEY (1745–1826)
• MURRAY, LORD GEORGE (1694–1760)
• MURRAY, SIR JAMES AUGUSTUS HENRY (1837– )
• MURRAY, SIR JOHN (1841– )

Murray system the messages are first prepared in the form of a strip of perforated paper about half an inch wide . Per- forating See also:

• MACHINES

machines equipped with typewriter keyboards Murray are used for the preparation of the messages, two or system. three keyboard perforators being employed at each end of the telegraph lines on which the Murray system is used . The messages in the form of perforated tape are then passed through an automatic transmitter, something like a Wheatstone transmitter, at a speed of about 10o words a minute . At the receiving station See also:

• ELECTRICAL
• ELECTRICAL (or ELECTROSTATIC) MACHINE

electrical mechanisms record the signals once more as perforations in a paper strip forming an exact replica of the transmitting tape . This received perforated tape is then used to control what is known as the printer or automatic typewriter, a See also:

• MACHINE
• MACHINE (through Fr. from Lat. form machina of Gr. µnxavil)

machine that translates the tape perforations into letters and prints the messages in See also:

• ROMAN

Roman type in See also:

• PAGE
• PAGE, THOMAS NELSON (1853- )
• PAGE, WILLIAM (1811-1885)

page form . This printer is purely mechanical, and its speed is very high . An experimental printer constructed about the middle of 19o8 by the British Post Office, operated successfully at the rate of 210 words (1260 letters) per minute . The usual working speed is from 10o to 120 words per minute .

The Murray automatic system was designed specially for dealing with heavy traffic on long lines . As it uses the Baudot telegraph See also:

• ALPHABET (see also WRITING)

alphabet it has an advantage in theory over the Wheatstone using the Morse alphabet in regard to the speed that can be obtained on a long telegraph line in the ratio of eight to five, and this theoretical advantage is more or less realized in practice . The Murray automatic system is not regarded as suitable for short telegraph lines or moderate traffi