Edward Weston (chemist) instruments for electric current—the modern foundation for the voltmeter, ammeter and wattmeter. In 1888 he formed the Weston Electrical Instrument Corporation which would become famous for its voltmeters, ammeters, wattmeters, ohmmeters, frequency meters, transformers, and transducers. Weston developed a method for producing a "true" permanent magnet. Weston conceived of and built a magnetic speedometer. Weston also developed the dashboard ammeter for Harley-Davidson motorcycles. Also in 1888, Weston became president of the American Institute of Electrical Engineers (AIEE) until 1889. Weston invented and patented the saturated cadmium cell in 1893. The cathode in the cell is an amalgam of cadmium with
Conventional electrical unit in this way, and as such, represent a significant step towards using "natural" fundamental physics for practical measurement purposes. However, the conventional electrical units are unlike other systems of natural units in that some physical constants are not set to unity but rather set to fixed numerical values that are very close (but not precisely the same) to those in the common SI system of units. Four significant steps were taken in the last half century to increase the precision and utility of measurement units. In 1967 the Thirteenth General Conference on Weights and Measures (CGPM) defined the second of