The ternary calculating machine of Thomas Fowler

A large, wooden calculating machine was built in 1840 by Thomas Fowler in his workshop in Great Torrington, Devon, England. In what may have been one of the first uses of lower bases for computing machinery, Fowler chose balanced ternary to represent the numbers in his machine. Very little evidence of this machine has survived.

Since 1997, two current Devon residents, Pamela Vass and David Hogan, have been researching Thomas Fowler and his inventions. They discovered a two-page description of Fowler’s calculating machine, written in 1840 by a prominent mathematician of the day, Augustus DeMorgan. Working together with Vass and Hogan, Mark Glusker designed and built the model shown above, based primarily on the information in DeMorgan's description.