Exploring our archives

Next month I’m taking the RMS ship to St Helena, following the route taken by several members of the Royal Society. This small Atlantic island was originally discovered in 1502-5 during Vasco da Gama’s journey to the East Indies and during the sixteenth century was visited (willingly and unwilling) by travelers as diverse as two teenage Japanese princes en route to visit the Pope and an unlucky follower of Afonso Albuqueque, who was marooned there after defecting to his enemy Prince Khan. It was also the site of what can be described as the first ever ’sci-fi’ novel, Francis Godwin’s 1638 ‘Man in the Moone’. The island passed between Dutch and English settlement before 1673, at which point the East India Company established their ‘government’ there. Edmund Halley visited in 1676 to determine the positions of stars in the northern hemisphere and to observe the transit of Mercury across the sun, for which purpose he built an observatory on the island (1). Halley’s trip to the island was also important for his observations of the magnetic declination of the earth, which would later form the basis of his atlases of the Atlantic and the world as well as making an important contribution to Newton’s Philosophiae Naturalis Principia Mathematica. Perhaps frustrated by having his observations so frequently interrupted by poor weather, Halley also wrote an article about the ‘watery vapours’ on the island, a piece sometimes hailed as an early example of climate environmentalism (2). Halley was followed almost a century later by Dixon and Mason, sent to observe the 1761 transit.

As an important transit point between the Atlantic and Indian Oceans, St Helena was a site for experimentation with agricultural and manufacturing techniques drawn from both worlds: growing different types of rice and wheat as well as coffee, which is still produced on the island. Many of these experiments were drawn from Asia, which remained far ahead of Europe in terms of manufacturing techniques in the seventeenth century (the most obvious example being textiles). Having tried unsuccessfully to persuade some of the Indian inhabitants of Madras to visit and demonstrate the making of indigo, the Company was forced to rely on the experience of their servants of agricultural and manufacturing techniques used in the East and West Indies. The Governor Isaac Pyke was a frequent correspondent of the Society and published a piece in Philosophical Transactions entitled ‘The Making of Mortar at Madras’ (3), which details the technique and his efforts to reproduce it on St Helena. I recently found the manuscript copy of this paper among the manuscripts held in Senate House, along with Pyke’s ‘hydrostatick’ method of calculating the composition of metals. Weighing composite metals in water and air was another frequent obsession of the Society’s during the seventeenth century, the results of these experiments being painstakingly recorded in the Hooke folio. Pyke’s MS alerted me to the practical applications of the method; showing the composition, and thus relative values, of different types of gold and silver coins.
1) Alan Cook. ‘Edmond Halley and the Magnetic Field of the Earth’. Notes Rec. R. Soc. Lond. 55 (3), 473–490 (2001)

2) Edmund Halley. ‘An Account of the Circulation of Watry Vapours of the Sea, and of the Cause of Springs. Philosophical Transactions, 192:17 (1694), 468-73.

3) Isaac Pyke. ‘The Method of Making the Best Mortar at Madras’. Philosophical Transactions, 37 (1731/1732), 231-235.

Comments :1

Did you see the lunar eclipse on Saturday night? Lunar eclipses occur when the earth blocks the sun’s light by passing between the sun and the moon and we see the earth’s shadow gradually cast across the moon. Although lunar eclipses are not particularly rare, with a clear sky, as on Saturday night, the sight of the moon with a red or copper hue is an impressive sight.

The Folio records accounts observing both solar and lunar eclipses and, interestingly, these were viewed as sufficiently important to be included in the index to the Folio. Such accounts tended to be in the form of letters, for instance in July 1782, Cassini writes to Flamstead, describing an eclipse of the moon in Dantizick, whilst in December 1685, Hevlius writes to Aston ,again with an account of a lunar eclipse in Dantizick. These descriptions are not confined to the Hooke Folio, however, and form part of a wider pattern of interest in lunar eclipses within the early Royal Society. For example accounts of eclipses are sent from various places including Paris and Moscow, whilst in 1666, Gresham-Professor of Geometry Mr Rook’s methods for observing a lunar eclipse are published in the Society’s Philosophical Transactions. He says that the observer, preferably using a telescope rather than the naked eye, should pick out three of the ‘eminentest spots’ which ‘lie nearest the ecliptick’ and note the time a shadow is first cast on each one and when they are ‘completely entered in’ and out of the shadow. Rook also comments that observing lunar eclipses is important, not only for the astronomical information that could be gleaned, but also for the geographical information, such as comparing how observations made by scientists in various countries both differed and converged.

If you missed Saturday’s eclipse, one should be visible (weather permitting) on July 16th, though only if you live in Asia, the Pacific or the West of the Americas, if you live in Europe then you’ll have to wait until 9th January.

Comments :0

In November 1681, the folio records that ‘Mr. Hooke Produced A new sort of Instrument for Describing the Rhombs or spirall lines vpon the Planisphericall projection on the pole of the world and shewed how the same would easily Describe all manner of Proportionall spiralls whether Greater or Lesse whether wider or narrower. And mentioned also what vse it might be for nauigation and sea charts.’ A few months later, Hooke produced a globe about a foot in diameter fitted with this instrument, and claimed that he could ‘thereby both Geometrically and mechanically Draw all the Rhumb lines vpon it most exactly’. A ‘rhumb line’, although sometimes used to indicate a straight line between two points on a Mercator chart, seems here to have its modern meaning of a curve that crosses each meridian at the same angle and the spirals Hooke refers to describe the way in which a rhumb spirals towards one of the poles.

The instrument designed by Hooke apparently had numerous applications: this is probably what he used in June that year to demonstrate the truth of Archimedes’ ancient theory on spirals, namely that ‘If a straight line drawn in a plane revolves uniformly any number of times about a fixed extremity until it returns to its original position, and if, at the same time as the line revolves, a point moves uniformly along the straight line beginning at the fixed extremity, the point will describe a spiral in the plane.’

Hooke later used the instrument in other ways, attaching it to a compass in order to describe a parabola. This apparently met with some opposition: at a meeting of 15 February 1682, it was noted that Flamstead had ‘cavilled against’ Hooke’s method, ‘affirming it to be fals’. On the repeated demonstration of the working of the instrument, however, the Society agreed that it was ‘true and certain and the best way yet known of describing that curve’. The final reference is in March 1682 and refers to the use of the instrument to describe an ellipse. By this entry Waller has noted ‘Quere Mr Hunt what this was and how performed’. Apparently, then the instrument and its method of use had been lost by the time Waller acquired Hooke’s papers in 1708. Richard Waller, a strong supporter of Hooke’s claims to priority had also made annotations against Hooke’s manuscripts about clocks or watches in Trinity College Cambridge – perhaps believing that they contained the solution to the long-term problem of longitude. He may, therefore, have also believed that this lost instrument was a significant piece of equipment in Hooke’s claim to have invented a new method of planispherical projection to be used in mapping.

Comments :0

A vaguely Valentine’s Day related post today

Observing the transit of Venus, the time at which the planet passes between the sun and earth, is a constant feature of the early records of the Royal Society, who received correspondence from around the world recording the precise times at which it was observed. The purpose of this romantic exercise, similarly to the mapping of the transits of Mercury, was to make observations relating to the position of the sun and planet, using the parallax method. This was pioneered by Edmund Halley, who explains the theory in Philosophical Transactions (translated here for those not keen to read the original in Latin). Mapping transits also has practical applications in navigation as it provides a natural clock with the aid of which longitudes, still a thorny problem in the seventeenth and eighteenth century due to the dearth of reliable timekeepers, could be calculated according to the difference in time between locations on a reference meridian. Perhaps this explains the interest of the East India Company, who allowed Halley to visit St Helena, where he built an observatory, the remains of which can still be observed on the island.

Halley’s work promoted international collaboration between scientists as well as voyages of exploration: most notably Captain Cook’s voyage to Tahiti to observe the 1769 transit. Romantics will have to wait a while to emulate the early stargazers, however, as the next transit is predicted to be visible in 2012.

Comments :0