Dental review; devoted to the advancement of dentistry. . ield from positive to negative, in a given space of time and leav-ing a broad, even band similar to this. We will suppose the line in the middle to represent the neutralpoint; the distance of the current from this neutral line will repre- Fig. 1. sent the potential, say 100 volts, passing from positive to negativewithin this space of time, say a second. The central figure will represent an alternating current with apotential of 150 volts, skipping about 50 times a second from positiveto negative and back again across the neutral line. T
Dental review; devoted to the advancement of dentistry. . ield from positive to negative, in a given space of time and leav-ing a broad, even band similar to this. We will suppose the line in the middle to represent the neutralpoint; the distance of the current from this neutral line will repre- Fig. 1. sent the potential, say 100 volts, passing from positive to negativewithin this space of time, say a second. The central figure will represent an alternating current with apotential of 150 volts, skipping about 50 times a second from positiveto negative and back again across the neutral line. The zig-zag linethus produced is a good example of an alternating street-lightingcurrent. The third figure gives one a faint idea of what a high-frequencycurrent may be represented to look like. In one second here weshould have some 200,000 or 300,000 lines, but they would be at sucha distance both sides of this neutral line and so close to each otheras to look like a haze or a blur. No pencil could portray them andno eye could follow them on the ORIGINAL COMMUNICATIONS. 729 Now, just in the same way that the human eye is blind to morethan a few hundred lines on a screen and blind also to light-wavesmore rapid than violet rays; just in the same way that the human earis deaf to more than 32,000 sound-waves a second, so is the humannerve limited in its perception of these immensely rapid electricalvibrations and wholly incapable of feeling them. Whilst slowly alternating or continuous currents are extremelydangerous, often fatal, these highly strung and rapidly alternatingcurrents pass absolutely unpreceived on and around the body, delug-ing it with ozone and producing on and around the point of applica-tion such an electric storm and such a stimulation of all vital energies
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