He had made his will on 19 July and was buried on 1 August, according to the registers in the precincts of the Collegiate Church which would later become Manchester Cathedral. Horrocks's and Crabtree's Yorkshire astronomical friend William Gascoigne who left no record of seeing the transit , moreover, had pre-deceased Crabtree by a few days, when, while serving as an officer in the Royalist army in the Civil War, he fell in the battle of Marston Moor on 2 July With these three north-country astronomers now dead, it is fascinating to see the speed with which like-minded men in the area - especially scientific friends of Christopher Townley in the Pendle and Burnley districts of Lancashire - began to collect up and preserve their surviving papers.
Moore even paid for Flamsteed's original set of instruments out of his own pocket. By the s, and within the early Royal Society, however, it is clear that the work of Horrocks and his Lancashire friends before was now coming to be recognized as possessing enormous scientific importance.
The surviving pieces of correspondence that had passed between Horrocks and Crabtree after - records of observations, Horrocks's treatise on the lunar orbit, Gascoigne's letters, and even drawings and actual parts of their instruments - were being brought to London.
Of course, the ravages of Civil War, it was known, were responsible for the loss of the bulk of their papers, while even more were destroyed when the printer's premises where some of them were going to be published was burnt down in the Great Fire of London in Enough manuscripts survived to enable Horrocks's Emmanuel contemporary John Wallis, now Savilian Professor of Geometry at Oxford, to publish, with the assistance of Robert Hooke and others, a substantial volume, the of Jeremiah Horrocks, under the Royal Society's imprimatur of Other pieces that subsequently came to light found their way into Philosophical Transactions over the years, and when Flamsteed published the first fruits of his 46 years as Astronomer Royal, he prefixed his own work with a set of Crabtree's and Gascoigne's hitherto unpublished astronomical observations.
Indeed, considering the number of letters, manuscripts and draft treatises that appeared in print between and , and in the light of what was said to have been lost, the sheer intensity of their original research and the volume of correspondence that passed between Horrocks, Crabtree and Gascoigne between and the early s are truly breathtaking.
Manuscript copies of Horrocks's treatise on the Venus transit had clearly been made during the s and s, though we have no idea how one of them travelled to the great Baltic seaport of Dantzig Gdansk and passed into the hands of the illustrious Polish astronomer Johannes Hevelius FRS. But one of them plainly did, for in Hevelius issued an elegant Latin impress of Horrocks's treatise from the private press at his great observatory-residence in Dantzig.
In this, its first printed edition, Horrocks's Venus in Sole Visa formed a companion piece to Hevelius's own observations of the Mercury transit. After , when the Townley family of Townley Hall, Burnley, sold off some of their collections, more Horrocks manuscripts found their way on to the market and it is possible that the copy of Venus in Sole Visa that Sir George Biddell Airy noted as coming to the Royal Observatory Library from the hand of his South-Yorkshire assistant William Richardson, in July , originated from this source.
Out of the blue, in early March , I was approached by Mark Westwood, of Hay-on-Wye, a scholar, academic book dealer and himself an Emmanuel College graduate, and invited to offer an opinion on three Horrocks manuscripts that had just been placed into his hands by their owner who wished to find a buyer. One of the Venus copies, in both Mr Westwood's and my own opinion, was in Horrocks's own hand; the other looked like a professionally produced scribal copy, probably made to be sent to a prospective publisher: the 17th-century version of a finished typescript.
I am glad to say that, after several major libraries, mainly in America, had been alerted to the forthcoming auction of these Horrocks documents, they were eventually acquired by Cambridge University Library.
I, for one, was very relieved that the Venus manuscripts had stayed in England and that Horrocks's alma mater now had them safely in her custody. As the above original manuscripts indicate, Horrocks wrote his Venus in Sole Visa in Latin and the Royal Society had the Horrocks and Crabtree correspondence translated into Latin for publication in Opera Posthuma - both clearly aimed at an international readership - and it was not until that Horrocks's magnum opus became available in English.
Jeremiah Horrocks and William Crabtree and their work on the transit of Venus have fascinated scientists and scholars for over years, for what both men did on that dull November afternoon in was far more than make a simple astronomical observation. The consequences of that observation, and its clear susceptibility to Copernican interpretation, would resonate throughout the learned world and signal that the European astronomical revolution had taken secure root in British soil.
And yet one should not forget that while this revolution in continental Europe had been the product of great universities, royal courts and cathedral chapters, it came about in England through the work of a small group of dedicated, self-funded amateurs living in rural Lancashire.
Now the deserved scientific and media excitement of the transit of Venus has passed, Allan Chapman offers a brief account of the career of Jeremiah Horrocks, who predicted and observed the transit. Google Scholar. Google Preview. Note that most of the references to original sources mentioned in this article are cited in full bibliographical detail in Chapman Oxford University Press is a department of the University of Oxford. It furthers the University's objective of excellence in research, scholarship, and education by publishing worldwide.
Sign In or Create an Account. Sign In. Advanced Search. Search Menu. Article Navigation. Close mobile search navigation Article Navigation. Volume Article Contents Abstract. William Crabtree. The demand for data. The importance of eclipses.
Correcting Kepler. Recognition and renown. Horrocks, Crabtree and the transit of Venus. Allan Chapman Allan Chapman. Historian of science at Wadham College, Oxford. Oxford Academic. Select Format Select format. Permissions Icon Permissions. Abstract British research astronomy began in , when Jeremiah Horrocks and William Crabtree observed the transit of Venus in Open in new tab Download slide.
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Being a diligent scientist, Horrocks realized his calculations might be slightly off, so he looked for the transit a day ahead of time from his home in the hamlet of Hoole now Much Hoole , just north of Liverpool. But his calculations were virtually bang-on, an incredible achievement given the fact that he had to perform all of his calculations by hand. A plaque hangs at the entrance of Carr House which still stands , where Horrocks made history. The inscribed date, November 24, , is from the old Julian calendar.
Modern calendars record the date as December 4th. On December 4th, Horrocks was called away to his local church around p. When he returned to his house around p. The transit was already in progress. Using a small refractor to project an image of the Sun, he was able to observe the transit for about half an hour before the Sun set below his horizon. He carefully measured Venus's angular diameter to be 1. His observations also refined human knowledge of Venus's orbit. Prior to the transit, Horrocks sent a letter with his prediction to his friend William Crabtree, who had been a fellow student at Cambridge University.
Crabtree observed the transit from his home in nearby Manchester. Crabtree, however, was so overcome with emotion that his notes contributed little to science.
Still, Horrocks and Crabtree became the first humans to see a transit of Venus while recognizing the event's true nature. There are no known records of anyone else in the world predicting or witnessing the transit. Tragically, Horrocks died of unknown causes just 14 months after the transit, leaving historians to speculate on what this incredibly talented scientist might have accomplished had he enjoyed a longer life.
Crabtree died a few years later, in , at the tender age of Edmond Halley devised an ingenious method to calculate the scale of the solar system by observing the transits of Venus from both hemispheres. Mercury rotates on its axis three times while it circles the Sun twice.
This synchronous rotation can be followed in the schematic diagram by observing the position of the dot which represents a fixed point on Mercury's surface as the planet moves from position 1 to 2, 2 to 3, The magnetic field observations provide independent evidence that Mercury possesses a large, metal-rich core. Probably the most anomalous property of Mercury is its high mean density of 5. However, Mercury is only about one-third the size of the Earth; its uncompressed average density of 5.
This indicates that Mercury is composed of 65 to 70 percent by weight of metal phase probably iron , and only some 30 percent by weight of silicate phase. Therefore, Mercury apparently contains twice as much iron in terms of percentage composition as any other planet in the solar system.
Measurements of the magnetic field and evidence of volcanism in the Mariner 10 photography suggest that Mercury is chemically differentiated. The gravity scaling of surface processes is the same for both bodies. The photometric, polarimetric, and thermal properties of Mercury derived from Earth-based measurements are very similar to those of the Moon and indicate a surface covered by a dark, porous, fine-grained particulate layer.
However, spatial variations in the thermophysical properties of this layer suggest large-scale regions of enhanced thermal conductivity which could be areas of more compacted soil, or areas in which boulders or outcroppings of rock are exposed. The best Earth-based telescopic photographs of Mercury have a resolution of about km. These photographic and visual observations show that the surface of Mercury consists of dark and light regions somewhat similar to the maria and highlands of the Moon seen at comparable resolution.
Although radar altitude profiles and reflectivity maps in the equatorial regions suggested the presence of a cratered surface, it was not known before the Mariner 10 mission that the topography was similar to that of the Moon.
Some believed that the crater density would be much less than that on the Moon or Mars because of Mercury's great distance from the asteroid belt, whereas others believed it would show a crater density comparable to that of the Moon. Questions concerning the presence or absence of volcanism, the tectonic framework, and the surface history were unresolved.
Mariner 10 dispelled many mysteries about Mercury and exposed its surface to detailed studies previously possible only for the Moon and Mars.
The best pictures of Mercury acquired by Mariner 10 have a resolution of m, an improvement by a factor of about over Earth-based resolution. As demonstrated by the pictures contained in this Atlas, the tremendous increase in resolution has resulted in a quantum jump in man's knowledge of the planet.
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