In 1660, he discovered
Hooke's law of
elasticity, which describes the linear variation of
tension with extension in an
elastic spring. In 1662, Hooke gained appointment as Curator of Experiments to the newly founded
Royal Society, and took responsibility for experiments performed at its meetings. His work on elasticity culminated, for practical purposes, in his development of the balance-spring or hairspring, which for the first time enabled a portable timepiece - a watch - to keep time with reasonable accuracy. A bitter dispute between Hooke and
Christiaan Huygens on the priority of this invention was to continue for centuries after the death of both; but a note dated 12 June 1670 in the Hooke Folio (see
External links below), describing a demonstration of a balance-controlled watch before the Royal Society, has been held to favour Hooke's claim.
In 1665 he published a book entitled
Micrographia which contained a number of
microscopic and
telescopic observations, and some original observations in
biology. Hooke coined the biological term
cell, so called because his observations of plant cells reminded him of
monks' cells which were called "cellula." He is often credited with the discovery of the cell, although his microscope was very basic.
The hand-crafted, leather and gold-tooled microscope that Hooke used to make the observations for
Micrographia, originally made by Christopher Cock in London, is on display at the National Museum of Health and Medicine in Washington, DC. Also in 1665 he gained appointment as Professor of
Geometry at
Gresham College. Hooke also achieved fame as Surveyor to the City of London and chief assistant of
Christopher Wren, helping to rebuild London after the
Great Fire in 1666. He worked on designing the
Monument, Royal Greenwich Observatory and the infamous
Bethlem Royal Hospital (which became known as 'Bedlam').
He died in
London on
3 March 1703 (ns). He amassed a sizeable sum of money during his career in London, which was found in his room at Gresham College after his death. He never married.