George Boole and Charles Babbage hold prominent places in the history of logic. But there are others, like William Stanley Jevons, who invented machines based on the principles of logic, capable of working as an extension of the human mind—machines rarely recognized by the general public. Jevons' Logical Piano was a kind of primitive computer, able to process logical terms and solve problems posed with them.
Jevons' Life and Education
William Stanley Jevons was born in Liverpool on September 1. He was the ninth child of a wealthy merchant family. He studied at University College London, where he was decisively influenced by Augustus de Morgan. After his family went bankrupt, he was forced to interrupt his education and emigrate to Australia. Five years later, his savings allowed him to return to England, complete his studies at University College, and eventually earn a Bachelor of Arts degree, followed by a Master of Arts degree two years later.
The Logical Piano
Jevons invented the first logical machine capable of using Boolean algebra to solve logical problems. The Logical Piano, named for its resemblance to a musical instrument, used an alphabet of four terms to solve complex syllogisms. It was one of the first devices able to solve such problems—and to do it faster than the human brain.
A syllogism is a form of deductive reasoning that consists of two propositions as premises and another as a conclusion, the latter being a necessary inference from the first two. The Logical Piano could draw valid conclusions—logically speaking—automatically, from the premises entered by the operator via its "keys".
This "grandfather" of modern computers contained only gears and levers inside. Unlike mechanical calculators, which were already common at that time, the Logical Piano used logical propositions as input instead of numbers. The output had the same nature, and results could be read on a series of indicators on its front panel.
Later Life and Legacy
Later, Jevons retired from teaching and devoted himself to writing. Several of his works focused on the principles of economic theory, rent, interest, and the productivity of capital. Unfortunately, he did not live to complete his projects; he drowned while swimming with his wife and three children in the sea near Hastings. He was not yet 47 years old.
The original Logical Piano is now in the Museum of the History of Science in Oxford. For more information, see William Stanley Jevons on Wikipedia.
