Ayrton, William Edward (1847-1908)

English physicist and electrical engineer. Ayrton invented many of the prototypes of modern electrical measuring instruments, including the ammeter. He also created the world's first laboratory for teaching applied electricity, in Tokyo, Japan, in 1873.

Ayrton was born in London and studied mathematics there at University College. He joined the Indian Telegraph Service and was sent to Bombay (now Mumbai) in 1868. In 1873 he became professor of physics and telegraphy at the new Imperial Engineering College in Tokyo, at that time the world's largest technical university. Returning to London, from 1879 he held various professorships in applied physics and electrical engineering.

In 1881 Ayrton and his colleague John Perry (1850-1920) invented the surface-contact system for electric railways, and they brought out the first electric tricycle in 1882. There followed a series of portable electrical measuring instruments, including the ammeter (so named by its inventors), an electric power meter, various forms of improved voltmeters, and an instrument used for measuring self and mutual induction. In this, great use was made of an ingeniously devised flat spiral spring which yields a relatively large rotation for a small axial elongation.