WIKE. 683 WIRELESS TELEGRAPHY. rope. Such rope is made in niucli the same form as hemj) rope. (See VVlUE Hope.) Wire netting is also made by machines which take the wire from bobbins and deliver the netting complete in rolls ready for slapping, t'onsult Smith. Wire: Its MuiiKfacI Krc and Uses (Xew York, 1801). WIRE GAUGES. Wire is made in a num- ber of sizes or diameters. To desifinate these sizes use is made of a .series of numerals each of which indicates a certain diameter in fractions of an inch where English measure is used and in millimeters where metric measure is employed. Such a series of numericall.v designated sizes is called a wire gauge. There are a number of such gauges in use. In England the legal gauge is the Imperial wire gauge, which was estab- lished by law in 1884. Previous to this time a number of wire gauges had been cm]jloved in England, the best known of which are the Stubbs wire gauge and the Birmingham wire gauge. France and Oermany have standard wire gauges based upon the millimeter. In the United States there are a niunber of different wire gauges, but they are nearly all precisely similar to the Roob- ling and Washburn-JIoen standard. The follow- ing table shows the two American wire gauges most used and the equivalents in the English legal standard: Number of Roebling'8 and Brown and .Sharpe's Equivalents in the wire p:au(^e Washburn- English legal U. S. A. Moen's gauge gauge U". S. A. standard, S. W'. G. in. in. in. 000000 .46 .464 00000 .43 .432 0000 .393 .46"" .4 000 .362 .40964 .372 00 .S31 .3648 .348
.307 .32495 .324 1 .283 .2893 .3 2 .203 .25763 .276 C .244 .22942 .252 4 .225 .20431 .232 5 .207 .18194 .212 6 .192 . 1(;202 .192 7 .177 .H428 .176 8 .162 .12819 .16 9 .148 .11443 .144 10 .135 .10189 .128 11 .12 .09074 .116 12 .105 .08081 .104 13 .092 .07196 .092 U .08 .06408 .08 15 .072 .05706 .072 16 .063 .05082 .064 17 .054 .04625 .056 18 .047 .0403 .048 19 .041 .03585 .04 20 .035 .03196 .036 21 .032 .02846 .032 22 .028 .02534 .028 23 .025 .02257 .024 24 .023 .0201 .022 25 .02 .0179 .02 26 .018 .01.594 .018 27 .017 .01419 .0164 28 .016 .01264 .0148 29 .015 .01125 .0136 30 .014 .01002 .0124 31 .0135 .00893 .0116 32 .013 .00795 .0108 33 .011 .00708 .01 34 .01 .0063 ,(H)92 35 .0095 .00561 .0084 36 .009 .005 .0076 WIRE GLASS. See Glas.s. WIRELESS TELEGRAPHY. The art of telegraphing without wires by electricity. It cornprises a number of different methods, of which the principal ones are those based on (1) dispersion or the leakage of electric currents when jjiojected into the earth or water; (2) magnetic lines of force set up in space by mag- netic induction; (3) strains in the intervening dielectric or mcilium separating the instrunjcnts due to electro-.static stresses or dillerenees of potential; and (4) radiation of electro-magnetie waves. Di.sPERSTON Method. This is also known as the leakage and as the conductivity method. In the simplest form of this arrangement four metal plates are placed in the earth or water in paral- lel as shown in the diagram Fig. 1. A represents Fig. 1. the sending station and B the receiving station; the distance separating the plates I, 2 and 3, 4 should be at least as great as tlve distance be- tween A and B, over which the signals are to be transmitted. At the sending station the plates 1, 2 are con- nected in series with a battery, 6, and a telegraph key, 5, by means of a wire. The earth com- pletes the circuit through which the current flows in the direction of the arrows. A portion of the current flowing through this circuit is dispersed through the earth, since the latter is a very good conductor owing to its immense cross section, and the leakage of the current takes place in form of elliptical lines, as in Fig. 2. A small III mmw '^MM{Ai
X..
^^^^-
portion of the electric current sent through the
circuit A finds its way to B, where the earth
again completes the circuit of the receiver. A
galvanometer, telephone, or other means of in-
dication may be used to receive the message.
A modification of this method is employed for
alternating currents. At the sending and receiv-
ing stations (Fig. 3) plates 1, 2. 3. 4 are placed
in the same relative positions as before, but an
interrupter, 7. is included in the circuit with the
battery. 0. and key. 5. which are connected with
the primary winding of an induction coil, 8; the
terminals of the secondary coil. 9, are connected
with the plates 1, 2; the direct current flows
