Signalling through space without wires : being a description of the work of Hertz & his successors . id, however, that the box must be exceedinglywell closed for the screening to be perfect. The very narrowestchink permits their entrance, and at one time I thought I shouldhave to solder a lid on before they could be kept entirely a copper lid on to a flange in six places was notenough. But by the use of pads of tinfoil and tight clamping, d 2 36 SIGNALLING WITHOUT WIRES. chinks can be avoided, and the inside of the box becomes thenelectrically dark. If even an inch of the circuit
Signalling through space without wires : being a description of the work of Hertz & his successors . id, however, that the box must be exceedinglywell closed for the screening to be perfect. The very narrowestchink permits their entrance, and at one time I thought I shouldhave to solder a lid on before they could be kept entirely a copper lid on to a flange in six places was notenough. But by the use of pads of tinfoil and tight clamping, d 2 36 SIGNALLING WITHOUT WIRES. chinks can be avoided, and the inside of the box becomes thenelectrically dark. If even an inch of the circuit protrudes, it at once becomesslightly sensitive again ; and if a mere single wire protrudesthrough the box, not connected to anything at either end,provided it is insulated where it passes through, the waveswill utilise it as a speaking tube, and run blithely in. Andthis happens whether the wire be connected to anything insideor not, though it acts more strongly when connected. In careful experiments, where the galvanometer is protectedin one copper box and the coherer in another, the wires con-. Fig. 20.—Spherical Radiator for emitting a Horizontal Beam, arrangedinside a Copper Hat, fixed against the outside of a metal-lined Box, whichcontains induction coil and battery and key. One-eighth natural wires pass into the box through glass tubes not shown. necting the two must be encased in a metal tube (Figs. 19oand 21), and this tube must be well connected with the metalof both enclosures, if nothing is to get in but what is when definite radiation is desired, it is well toput the radiator in a copper hat open in only one direction(Fig. 20), and in order to guard against reflected and collateralsurgings running along the wires which pass outside to theexciting coil and battery, as they are liable to do, I amaccustomed to put all the sending apparatus in a packing case WORK OF HERTZ LECTURE. 37 lined with tinfoil, to the outside of which the sending hat
Size: 1632px × 1530px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, bookidsi, booksubjectelectricity
