Tank Phones

The efficiency of a radio telephone, evolved by Captain K. E. Hartley of the British Territorial Forces, for use in army tanks, was exhibited last week on Salisbury Plain, England. Any member of a tank crew could operate it. Fine tuning had been eliminated by employing low frequency waves and a powerful, seven-tube superheterodyne receiver. Padded headphones protected the listener from internal and external din. The aerial, a hollow aluminum rod ten feet high, was equipped with a spring hinge to let it fold on the tank roof going under trees or bridges, rise erect again when they were passed.