Did Robert Hooke really invent the anchor escapement?

Robert Hooke | England’s Leonardo

Robert Hooke was an English natural philosopher, architect, and polymath. Born 18th July 1635 in Freshwater, Isle of Wight, and died 3rd March 1703 (aged 67) London, England.
As a young adult, he was a financially impoverished scientific inquirer but came into wealth and a good reputation following his actions as Surveyor to the City of London after the great fire of 1666 (in which he appears to have performed more than half of all the surveys after the fire).

At that time, he was also the curator of experiments of the Royal Society, and a member of its council, Gresham Professor of Geometry. He was also an important architect of his time though few of his buildings now survive and some of those are generally misattributed and was instrumental in devising a set of planning controls for London, the influence of which remains today.

Hooke studied at Wadham College, Oxford, during the Protectorate where he became one of a tightly knit group of ardent Royalists led by John Wilkins. Here he was employed as an assistant to Thomas Willis and to Robert Boyle, for whom he built the vacuum pumps used in Boyle’s gas law experiments, and conducted the experiments themselves. He built some of the earliest Gregorian telescopes and observed the rotations of Mars and Jupiter.

In 1665 he inspired the use of microscopes for scientific exploration with his book, Micrographia. Based on his microscopic observations of fossils, Hooke was an early proponent of biological evolution. He investigated the phenomenon of refraction, deducing the wave theory of light, and was the first to suggest that matter expands when heated and that air is made of small particles separated by relatively large distances. He proposed that heat was the manifestation of faster movement of the particles of matter.

He performed pioneering work in the field of surveying and map-making and was involved in the work that led to the first modern plan-form map, though his plan for London on a grid system was rejected in favor of rebuilding along the existing routes. He also came near to an experimental proof that gravity follows an inverse square law, and first hypothesised that such a relation governs the motions of the planets, an idea which was developed by Isaac Newton, and formed part of a dispute between the two which caused Newton to try to erase Hooke’s legacy. He originated the terraqueous globe theory of geology, disputed the literal Biblical account of the age of the Earth, hypothesised the idea of extinction, and wrote numerous times of the likelihood that fossils on hill and mountain tops had been raised there by “earthquakes”, a general term of the time for geological processes. Much of Hooke’s scientific work was conducted in his capacity as curator of experiments of the Royal Society, a post he held from 1662, or as part of the household of Robert Boyle.

Hooke’s work in Horology

Hooke made tremendously important contributions to the science of timekeeping, being intimately involved in the advances of his time; the introduction of the pendulum as a better regulator for clocks, the balance spring to improve the timekeeping of watches, and the proposal that a precise timekeeper could be used to find the longitude at sea.

Anchor escapement.

anchor escapement invented by Robert Hooke

Anchor escapement

In 1655, according to his autobiographical notes, Hooke began to acquaint himself with astronomy, through the good offices of John Ward. Hooke applied himself to the improvement of the pendulum and in 1657 or 1658, he began to improve on pendulum mechanisms, studying the work of Giovanni Riccioli and going on to study both gravitation and the mechanics of timekeeping.

Henry Sully, writing in Paris in 1717, described the anchor escapement as an admirable invention of which Dr. Hooke, formerly professor of geometry in Gresham College at London, was the inventor. William Derham also attributes it to Hooke.

Robert Hooke and the Watch balance spring.

Hooke recorded that he conceived of a way to determine longitude (then a critical problem for navigation), and with the help of Boyle and others, he attempted to patent it. In the process, Hooke demonstrated a pocket-watch of his own devising, fitted with a coil spring attached to the arbor of the balance. Hooke’s ultimate failure to secure sufficiently lucrative terms for the exploitation of this idea resulted in its being shelved and evidently caused him to become more jealous of his inventions it is alleged.

Hooke developed the balance spring independently of and at least 5 years before Christiaan Huygens, who published his own work in Journal de Scavans in February 1675.

In later life, Hooke became party to jealous intellectual disputes, which may have contributed to his relative historical obscurity outside of his association with Newton in particular.