Robert Hooke and Micrographia
|Fig 1. Cells in cork tree bark. From Hooke’s Micrographia via the Encyclopaedia Britannica.|
It is perhaps rash to attempt to appraise the work of Robert Hooke (1635–1703), but renewed attention is merited to a great scientist whose contribution to medicine and science has not been adequately acknowledged.
Robert Hooke was a scientist and biologist who, at a time when science was young and not yet too compartmentalized,1 made discoveries in an extraordinarily wide range of subjects—astronomy, meteorology, physics, and geology. His research on cardio-respiratory physiology and cellular biology was of cardinal importance to medicine. His discovery of cells and his book Micrographia are considered amongst the most important scientific works of the seventeenth century.
He is known for his work on the laws of elasticity, based on his experiments on springs. Hooke’s law states that the extension of a spring is directly proportional to the applied force. Thus, he invented the balance spring for watches, which modified the older pendular movement. He demonstrated the principles of hydraulics in Utiurus: or, The Doctrine of the Springs of Water (1682).
He discovered craters on the moon, surfaces of planets, the effects of the sun’s gravity, the axial rotation of Jupiter, and seventy-eight stars in the Pleiades. He produced evidence that gravity follows an inverse square law by a force inversely proportional to the planets’ distance from the sun. In 1678, Hooke applied this law to Kepler’s orbital motion of planets. The idea was developed independently by Isaac Newton in his Philosophiæ Naturalis Principia Mathematica (1687). Hooke also investigated the phenomenon of refraction, deducing the wave theory of light, and was the first to suggest that matter expands when heated.
Stephen Inwood’s biography, The Man Who Knew Too Much,2 records that Hooke devised thermometers, telescopes, microscopes, pendulums, and pumps—as well as a pedometer, a marine barometer, a depth sounder, and several navigational instruments. Andrade’s Wilkins Lecture fully details his numerous experiments and inventions.3
Physiology and biology
His most significant contributions to medicine were founded in the nascent fields of biology and physiology. Robert Boyle’s (1627–1691) experiments on gases resulted in “Boyle’s law,” which states that at a fixed temperature the volume of gas is inversely proportional to the pressure exerted by the gas. He secured Hooke’s inventiveness in his further experiments. Hooke devised a vacuum pump that could evacuate a vessel in which a candle could not burn and a clapping bell was silent, proving that air is necessary for combustion and for the conduction of sound. Hooke and Boyle’s experiments on gases led to investigations of high-altitude physiology and hypoxia.
Hooke made important discoveries about the structure and function of the respiratory system.4 He was able to:
keep a dog alive by blowing into his lungs, and even without the motion of his lungs, only by keeping them extended with a constant supply of fresh air: It was not the subsiding or movelessness of the lungs, that was the immediate cause of death, or the stopping of the circulation of the blood through the lungs, but the want of a sufficient supply of fresh air.5
|Fig 2. Micrographia (1665). Via the British Library.
He assisted and advised Thomas Willis’s eminent collaborator Richard Lower (1631–1691) who showed that the arterial blood owes its red color to the admixture of air in the lungs, and that the venous blood owes its dark color to loss of air during its passage through the body.
He observed in the louse “the very swift systole and diastole the blood seem’d drawn,” and he confirmed Harvey’s ideas on circulation (De Motu Cordis, 1628)* when he deduced:
to order all the inferiour services of the lower Faculties…
it is to begin with the Hands and Eyes, and to proceed on through the Memory, to be continued by the Reason; nor is it to stop there, but to come about to the Hands and Eyes again, and so, by a continual passage round from one Faculty to another, it is to be maintained in life and strength, as much as the body of man is by the circulation of the blood through the several parts of the body, the Arms, the Feet, the Lungs, the Heart, and the Head.6
Anticipating Luigi Galvani’s work on muscular contraction after electrical stimulation of frog nerves (1791), in 1678 Hooke reported to the Royal Society his observations in the lobster’s claw of the lengthening and contracting of the muscles fibrils during movement:
The muscle was that of a lobster’s claw, the fabric of which was such, that all the motion must necessarily be made in the fibrous part thereof; since first the tendon is nothing else but a bone, and so not capable of shrinking or stretching…
The cell and Micrographia
Hooke devised one of the earliest microscopes and with it was the first to show the cell. It is trite to observe that there can be nothing more fundamental or significant than the discovery of the cell, which underlies our understanding of the unit of life, fundamental to medicine and biology. He demonstrated the porous cells of Quercus suber, the cork tree (which contained no nucleus), and described them (Fig 1) in Micrographia, 1665:6
… these pores, or cells…were indeed the first microscopical pores I ever saw, and perhaps, that were ever seen, for I had not met with any Writer or Person, that had made any mention of them before this…
Soon after Hooke, in 1670, Antony van Leeuwenhoek observed single-celled bacteria—animalcules—after which cell theory was developed by Theodore Schwann (1810–1882) and Mathias Schleiden (1804–1881) who proposed that cells were the building blocks of life.7 Rudolf Virchow (1821–1902) advanced this idea.
Micrographia (Fig 2) contained magnificent engravings based on his drawings of the specimens he had examined with his compound microscope.
He described the surface of frozen urine, the eye of a grey drone-fly, a piece of moss, and the bodies of a louse, an ant, and a flea. One of the most famous illustrations is a drawing of a flea, and the text celebrated the “beauty of this tiny wingless flea, adorn’d with a curiously polish’d suit of sable [black] armour and multitudes of sharp pinns, shap’d almost like Porcupine’s Quills” (p. 210).
Alongside his engravings, he wrote entertaining observations:
The ant was so ‘troublesom to be drawn’ (p. 203) that Hooke sedated him with ‘Brandy’ which ‘knock’d him down dead drunk, so that he became moveless’ (p. 204). It was only after ‘an hour’ that the ant ‘suddenly reviv’d and ran away’, blowing out small bubbles (p. 204).6
Hooke’s prolific astronomical observations and theories are found at the end of Micrographia. He had devised a new Gregorian telescope, with which he was able to observe that Mars and Jupiter rotated on their axes. He described gravity as the force that draws celestial bodies together, relating in a 1679 letter to Newton a version of the inverse-square law of gravitational force.
He rightly inferred that the presence of fossilized fish in mountainous areas meant they had once been underwater. This study of fossils led him to conclude, like Darwin, that the Earth has been inhabited by many extinct species.
Robert Hooke FRS
|Fig 3. Progress: Robert Hooke, 1635–1703, Engineer. Oil painting on board based on published descriptions, Rita Greer, 2011. Via Wikimedia. Free Art License 1.3.|
Robert Hooke was born on 18 July 1635 at Freshwater, Isle of Wight, where his father John was curate of the parish. He was educated in the Elysian fields of Westminster School in London where the disciplinarian headmaster Dr. Richard Busby recognized his brilliance. Remarkably, Busby could boast many illustrious pupils who included Christopher Wren, John Dryden, John Locke, Matthew Prior, Henry Purcell, and Richard Lower. Hooke studied at Wadham College, Oxford where he became an assistant to Robert Boyle and the physician Dr. Thomas Willis.
His adult life comprised three distinct periods: firstly, as an impecunious scientific investigator; then, after the Great Fire of London 1666, he achieved wealth and respect by means of his prolific inventions; and finally, his terminal isolation and illness.
From 1662, as part of the household of Robert Boyle, he was simultaneously the curator of experiments of the Royal Society, a member of its council, the Gresham Professor of Geometry, and Surveyor to the City of London. He performed more than half of all the surveys after the Great Fire and devised the first modern map of London on a grid system.
He was renowned for his tireless services to the Royal Society, and for a time produced new experiments or discoveries at practically every meeting. Edward Neville da Costa Andrade’s Wilkins Lecture to the Royal Society (December 1949) described Hooke as:
Probably the most inventive man who ever lived, and one of the ablest experimenters, he had a most acute mind and made astonishingly correct conjectures, based on reason, in all branches of physics. Physics, however, was far from being his only field…3
In addition to his scientific work, the versatile Hooke was an accomplished architect. After the Great Fire of London, with his friend Christopher Wren, he took a major part in constructing many buildings, not least the Royal College of Physicians in Warwick Lane, the Royal Society’s headquarters, and the monument and dome of St. Paul’s Cathedral.
The Posthumous Works of Robert Hooke (1705) was published but many of his lectures, correspondence, and other writings were not.8
A vexing though essentially benevolent man of integrity, Hooke received much vindictive criticism. He was notoriously a prickly, competitive character who resented the denial of due credit for many of his discoveries. Indeed, the Royal Society’s secretary Henry Oldenburg often failed to enter his discourses in the Minute Book.3 Like Leonardo, having dealt with a project to his satisfaction, Hooke often abandoned the final polishing and publication and then felt aggrieved when someone else elaborated his work without proper acknowledgement. The Royal Society’s failure for many years to elect him to its council also rankled.
He was a contemporary of Sir Isaac Newton and the two men had an infamously hostile relationship.9,10 Newton was renowned as a philodox, and for his disputes with John Flamsteed, the first Astronomer Royal, and Gottfried Wilhelm Leibniz, philosopher, mathematician, and logician. Flamsteed described Newton as “excessively covetous of praise, vengeful and impatient of contradiction.” Hooke courteously criticized Newton’s 1672 paper New Theory of Light and Color that showed light traveled in straight lines consisting of particles. This theory could not explain diffraction, the bending of light rays, which Hooke had discovered. The arguments between the two great men increased when in 1686 Newton published Principia and Hooke claimed that he had given him the idea that led to Newton’s law of universal gravitation. Hooke demanded credit for the idea. Newton denied it. Such was Newton’s preeminence that his antipathy probably resulted in Hooke’s relative obscurity in the eighteenth and nineteenth centuries. Not until Hooke’s death did Newton accept the presidency of the Royal Society (1705) and publish his famous monograph Opticks.
The health of the lonely, ascetic Hooke deteriorated in 1697. He suffered from swollen legs, chest pains, insomnia, visual impairment, and possibly gangrene of the feet. Unmarried, he became neglected, ragged, and emaciated. He died alone. He was “handsomely interred” in St. Helen’s Church, Bishopsgate, in an unmarked grave.
Often unkindly described as crooked, ugly, and mean-looking, there are no known portraits of Hooke. (Newton was accused of destroying them.) His friend, the antiquarian biographer John Aubrey described him as “something crooked, that his head was large but the lower part of his face little and that his grey eyes were ‘full and popping’.” Rita Greer, a history painter, in 2011 from such written descriptions produced an imaginative oil painting illustrating some of his inventions (Fig 3).
* Translated into English in 1653
- Gest H. Homage to Robert Hooke (1635–1703): New Insights from the Recently Discovered Hooke Folio. Perspectives in Biology and Medicine 2009;52(3):392-399.
- Inwood S. The Man Who Knew Too Much: The Inventive Life of Robert Hooke, London, Macmillan, 2002.
- Andrade Edward Neville Da Costa. Wilkins Lecture – Robert Hooke. Proc. R. Soc. Lond 1950; B137153-187.
- West JB. Robert Hooke: Early Respiratory Physiologist, Polymath, and Mechanical Genius. Physiology 2014; 29:4, 222-233.
- Hooke R. An account of an experiment made by Mr. Hook, of preserving animals alive by blowing through their lungs with bellows. Phil Trans R Soc Lond 1667;2: 539–540.
- Hooke R. Micrographia. published by the Royal Society, 1665. British Library. https://bl.uk/collection-items/micrographia-by-robert-hooke-1665.
- Pearce JMS. The Beginnings of Cell Theory: Schleiden, Schwann, and Virchow. Hektoen International Summer 2022.
- Keynes G. A Bibliography of Dr. Robert Hooke. Oxford, UK: Clarendon Press, 1960.
- Chapman A. England’s Leonardo: Robert Hooke (1635-1703) and the art of experiment in Restoration England. Proceedings of the Royal Institution of Great Britain 1996;67:239-275.
- Rowbury R. Robert Hooke, 1635–1703. Science Progress 2012 95:3, 238-254.
JMS PEARCE is a retired neurologist and author with a particular interest in the history of medicine and science.