. Nature . nd consequently every five seconds thelittle brush wipes against the convex surface of one ofthem. Each of these pins is connected with one terminalof a battery B, the other side of the battery leading to therelay R, as does also the centre seconds hand. There-fore each time the brush wipes against a pin the circuitis closed, and the relay throws into action the local circuitconnected up with the terminals TT. This circuit excitesan electromagnet, which attracts an armature and pullsaway the check which is holding back the cylinder. Atthe end of each 5 seconds the cylinders conseque
. Nature . nd consequently every five seconds thelittle brush wipes against the convex surface of one ofthem. Each of these pins is connected with one terminalof a battery B, the other side of the battery leading to therelay R, as does also the centre seconds hand. There-fore each time the brush wipes against a pin the circuitis closed, and the relay throws into action the local circuitconnected up with the terminals TT. This circuit excitesan electromagnet, which attracts an armature and pullsaway the check which is holding back the cylinder. Atthe end of each 5 seconds the cylinders consequently re-commence turning. Well calibrated clocks of the pattern used will keepgood time for the period taken to transmit a picture, onegaining on the other quite an inappreciable amount,depending on the friction of the brush against the this means the two cylinders are kept in very fairsynchronism independently of any wireless communication,and the less the interval between the stopping and restart-. ing of the cylinders be made, the more accurate and satis-factory will be the effect. The other method of synchronising is controlled byelectromagnetic oscillations. Let us suppose that acoherer is being used as cymoscope; the transmittingcylinder is kept running without any interruption, but bymeans of a fleeting contact it sends out a wave at theconclusion of its turn, a bare space in the picture beingnecessary about half a second beforehand, so that no wavesare sent out for the half-second previously. The receivingcylinder is driven too quickly, and checked at the end ofthe revolution. It then, by means of a cam pressingdown a spring lever, throws out of circuit the markingcurrent, and brings into circuit the relay which actuatesthe electromagnetic release. Consequently, when thesynchronising wave is received, the coherer causes therelay to work, the release is effected, and the receivingcylinder starts a new revolution in unison with thetransmitter. This means of synchr
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Keywords: ., bookcentury1800, booksubjectnaturalhistory, booksubjectscience
