James Clerk Maxwell developed very detailed mechanical analogies of electrical phenomena. He was the first to associate force with voltage (1873) and consequently is usually credited with founding the impedance analogy.[60] This was the earliest mechanical-electrical analogy.[61] However, the term impedance was not coined until 1886, long after Maxwell's death, by Oliver Heaviside.[62] The idea of complex impedance was introduced by Arthur E. Kennelly in 1893, and the concept of impedance was not extended into the mechanical domain until 1920 by Kennelly and Arthur Gordon Webster.[63]