Thomas Fowler

Thomas Fowler (1777 – 31 March 1843) was an English inventor whose most notable invention was the thermosiphon which formed the basis of early hot water central heating systems. He also designed and built an early mechanical calculator.

Life Much of the knowledge of Fowler comes from his son, the Reverend Hugh Fowler, who produced a biography of his father which was published in the Transactions of the Devonshire Association in 1875. He was born in 1777 in Great Torrington, Devon and lived his whole life there. His father was a cooper and he received a basic education at a local school. At about the age of 13 he was apprenticed to a fellmonger. He was largely self-taught, with a particular interest in mathematics, teaching himself from such works as John Ward's Young Mathematician's Guide and Nicholas Saunderson's work on fluxions: The Method of Fluxions. He established himself as printer and bookseller, later becoming a partner in and manager of the local bank. He was also the treasurer of the Torrington Poor Law Union. He married Mary Copp in 1813 and they had eleven children, many of whom died before reaching adulthood. The window was commissioned by his son Hugh around 1864.

Inventions

Thermosiphon Fowler patented the thermosiphon in 1828 (British patent number 5711). It was the first convective heating system. A system based on his design was installed at Bicton, part of the Rolle Estate and received great acclaim in the Gardener's Magazine of 1829. Unfortunately due to innate flaws in the patent system of the time (under which a new version of a design with minimal changes was not covered by the original patent), the thermosiphon was copied by numerous other manufacturers and Fowler did not have sufficient funds to conduct legal proceedings.

Calculating machine In 1840 Fowler produced a mechanical calculating machine which operated using balanced ternary arithmetic. This machine was designed to give mechanical form to the techniques described in his book, Tables for Facilitating Arithmetical Calculations. The choice of balanced ternary allowed the mechanisms to be simple, though the values had to be converted to balanced ternary before processing and the results converted back to decimal at the end of the calculation.

Apprehensive in case his ideas should again be stolen, he designed and built the machine single-handed from wood in the workshop attached to his printing business. To compensate for the limited precision achievable using wooden components, he constructed the machine on a large scale; it was 6 feet long by 3 feet deep and 1 foot high (1800 x 900 x 300 mm). The use of balanced ternary meant that the machine was not suitable for performing addition and subtraction because of the overhead of the conversion to and from base 10. It was more useful for problems (like those Thomas Fowler needed to solve as Treasurer of the Poor Law union) where there are a large number of intermediate calculations in between the conversions to and from ternary. It could perform both multiplication and division.

Though the machine did not survive to the present day, a replica has been constructed from a two-page description of it made in the 1840s by the prominent mathematician Augustus DeMorgan. Starting in 1999 a team of Mark Glusker, Pamela Vass and David Hogan created a concept model of the most simple machine that satisfies the description written by Augustus DeMorgan. The completed model was presented to the Great Torrington Museum in August 2000. This replica now resides at the Science Museum in London. The team are looking for funding to find more evidence about the machine's operation and appearance, and then to build the entire 55-digit machine that Fowler envisioned using techniques and materials more appropriate to the 19th century.

Publications 1829. A Description of the Patent Thermosiphon.

1838. Tables for Facilitating Arithmetical Calculations in Poor Law Unions.