DR. C. V. DRYSDALE, director of scientific research at the Admiralty, whose impending retirement is announced, has long been recognised as an authority on electrical measurements. In the early part of this century, while in charge of the Electrical Engineering Department of the Northampton Polytechnic Institute, he devoted considerable attention to measurements in the alternating current circuit, and his work on the dynamometer wattmeter, and particularly the development of the double element instrument for the measurement of polyphase power, is now well known. This was followed by several important contributions to technical literature on alternating current measurements, and included his pioneer work on the design of instrument transformers. The regenerative dynamometer together with the cone stroboscope were also devised at about this time for the equipment of the laboratories. He also investigated the possibilities of lising iron cores in dynamometer instruments and had some of the first iron-cored wattmeters built to his design which gave remarkably good performance. The simple phase shifting transformer was also designed and built, being originally intended to facilitate testing the performance of wattmeters at low power factors, and eventually this apparatus made possible his adaptation of the direct current potentiometer to the measurement of alternating potentials. This was the first self-contained instrument for this purpose, and in connexion with it he designed the first vibration galvanometer with tuning effected by variation of the magnetic control. He also gave considerable attention to accurate resistance measurement and devised a new form of standardising bridge which was a combination of the Kelvin and Carey Foster principles, and allowed of precise comparisons between standards over a wide range of values to be made with great accuracy and rapidity, and in connexion with this bridge he developed a novel and accurate ohm standard ingeniously compensated for temperature change. Some time later he designed low resistance standards with very small time constants for use in alternating current circuits.