EARTH CURRENTS

Timaru Herald, Volume CXLIV, Issue 21014, 18 April 1938, Page 6

EARTH CURRENTS

Telegraph Transmission Impeded | The normal routine of the local 1 telegraph service was somewhat upset | during Saturday afternoon and even- | ing by the affects of earth currents I which intermittently caused transmitted signals to fade out and thus | temporarily slow up the passing of messages. This electrical phenomenon, which appears at irregular intervals, first made itself manifest about 5 o’clock and reached its maximum at 8.30 o’clock. By 9.30 p.m. it had entirely disappeared. During the maximum period the strength of the earth currents caused the normal working currents of the telegraph apparatus fade right away, and then it became necessary for the local office to transmit the traffic of nearby stations which usually circulates via Christchurch. Both the teleprinter and Morse systems were affected; the latter to a lesser degree. At times the intensity of these stray or vagrant currents completely neutralised the working effect of the telegraphic batteries used to actuate the instruments. Telegraph officers however, overcome the effect of earth currents by the use of metallic circuits, and by this means traffic is kept flowing as usual. A telegraph officer remarked to a “Herald” representative that there appears to be some connection between earth currents and the periodic outbursts of magnetic particles or corpuscles from sunspots. These are transmitted earthwards in a succession of “clouds” and when they reach th 3 earth earth-currents are generated, apparently, by the particles of ionised electricity cutting across the earth’s magnetic field. As a general rule the intensity of earth currents is greater in the South Island than in the North Lriand. and greater on the West Coast of the South Island than on the East Coast circuits. These currents are also highly prognostic of the Aurora Australis or “Southern Lights’” displays. The last local visitation of earth currents was in January and this coincided with an Aurora both in the ■ Northern and Southern Hemispheres. >ln this connection it is said that when the discharged electrons from the sun enter the earth’s atmosphere the impact is observed in the Aurora, which is due to the effect of the violent collisions j between the atomic particles and the I earth’s magnetic field giving rise to the generation of light. Earth currents have no effect on telephone or tolls circuits which are of metallic construction and they are too weak m effect to influence electric power supply lines.