Methods of measurement of high electrical pressures

The need of some convenient and accurate method of measuring high electrical pressures has been felt for a number of years. The trend of modern development in electrical transmission of power toward higher pressures will doubtless make this need more and more urgent. The testing of dynamos, transformers, switches, cables, etc., at several times normal pressure, as a specified condition of their acceptance, is not infrequently the cause of considerable controversy as to whether the proper pressure test has actually been applied.