If the Rules in the Standards of the A. I. E. E. are a sufficient criterion of the quality of the cable, then the thicknesses of insulation ordinarily used for transmission cables in this country can be very materially reduced, as cables with the present thicknesses of insulation with material and workmanship of the first quality, will pass the tests prescribed by the Standards of the A. I.E. E. with a wide margin frequently exceeding 100 per cent.