On 2 June 1644 one of the biggest battles of the English Civil War took place on Marston Moor just outside of the city of York. The Parliamentary forces under Fairfax had, together with the Scottish Covenanters under the Earl of Leven had been besieging York, the principle Royalist stronghold in the North, the defence being led by the Marquess of Newcastle. Prince Rupert came to the aid of the beleaguered city with a substantial royalist army. Newcastle boke out of the city with his cavalry and joined Rupert and the two armies clashed on Marston Moor. The battle ended in a disastrous defeat for the royalist forces and marks a significant turning point in the war.
This is all well and good but at first glance doesn’t appear to have a lot to do with the history of science. However if we zoom in a little closer Marston Moor actually has two connections with that history. William Cavendish, the Marquess of Newcastle, and his brother Charles were both actively engaged supporters of the new sciences developing at the time in Europe and having fled England following the royalist defeat, they eventually ended up in Paris as part of the court of Queen Henrietta Maria. Here the Cavendish brothers became part of a philosophical circle dedicated to the investigation of science that included Marin Mersenne, Kenelm Digby and Thomas Hobbes. In Paris William also met and married Margaret Lucas, one of Henrietta Maria’s chamber maids, who would later become notorious as Margaret ‘Mad Madge’ Cavendish, a female philosopher of science and extensively published author.
Our second history of science connection to the Battle of Marston Moor is a less happy one because amongst the 4 000 royalist soldiers who are estimated to have died there was the astronomer, inventor and instrument maker William Gascoigne (1612–1644). Gascoigne is today mostly only known to those interested in the fine details of the history of the telescope, something that hasn’t changed much since his own times when he only became widely known after his most important invention, the micrometer, was claimed by the Frenchman Adrien Auzout (1622–1691) in 1666, twenty two years after his untimely death.
Gascoigne was born into the landed gentry in the village of Thorpe-on-the Hill near Leeds. Little is known of his childhood or education, although he claimed to have studied at Oxford University, a claim that cannot be confirmed. Like many amateur astronomers Gascoigne was self taught and appears to have been a very skilled instrument maker as he made all of his telescopes himself, including grinding his own lenses. One of the problems of early telescopes was measuring the size of celestial objects viewed through them. There is no easy solution to this problem when using a Dutch or Galilean telescope, i.e. with a plano-convex objective and a plano-concave eyepiece, and Galileo soled the problem by attaching a metal grid to the side of his telescope and viewing the object under observation through the telescope with one eye whilst observing the grid with his other eye. A trick that is thought to have been possible for Galileo because of an optical peculiarity he seems to have been born with. This method could only produce rough approximate sizes.
The Keplerian or astronomical telescope, where both objective and eyepiece lenses are convex, provides a much simpler solution. The Focal plane is at the juncture of the two focal lengths of the lenses, which is inside the telescope tube, and here the Keplerian telescope produces a its image. It appears that Gascoigne was the first to utilize this fact. There is a story that Gascoigne was made aware of this phenomenon by a spider that had woven its web in his telescope tube in the crucial position allowing him to focus on what he was viewing and the spider’s web at the same time. The story is probably apocryphal bur astronomers continued to collect spider’s silk from the hedgerows to form the crosshairs in their astronomical telescope well into the nineteenth century. Whatever led Gascoigne to the discovery of the internal image, he soon went beyond the simple expedient of installing crosshairs into his telescopes.
Gascoigne realised that this phenomenon would enable him to introduce a measuring device into the focal plane of his telescope and this is what he did. He produced a calliper the points of which could be moved towards or away from each other by means of turning a single screw. Along the base along which the calliper points moved was a measuring scale. Gascoigne could now make accurate measurements of the celestial objects he observed.
Being a self taught amateur astronomer and living as he did in a small northern village in an age when long distance communication was difficult and unreliable one might be forgiving for thinking that Gascoigne was isolated and to some extent he was but not completely. He communicated by mail, for example, with William Oughtred inventor of the slide rule and mathematics teacher of several notable seventeenth century mathematicians. This contact seems to have been initiated by Gascoigne who was surprisingly well informed about actual developments in mathematics and astronomy and is known to have owned all of the relevant literature. Through Oughtred Gascoigne was also introduced to Kenelm Digby with whom he also corresponded.
Perhaps more significantly Gascoigne was in contact with the Towneley family of Towneley Hall near Burnley, landed gentry who took an interest in the actual developments in mathematics and astronomy.
Christopher Towneley (1604–1674) introduced a group of northern astronomers to each other including William Milbourne of Christ’s College Cambridge (M.A. 1623), William Crabtree a merchant from Salford, Jeremiah Horrocks curate from Much Hoole near Preston and Gascoigne. Crabtree and Horrocks, famously, were the first astronomers to observe a transit of Venus. Crabtree and Gascoigne became good friends with Crabtree visiting Gascoigne to view and inspect his instruments and the two of them corresponding extensively on both Gascoigne’s instrumental novelties and the contemporary developments in astronomy, in particular the theories of Johannes Kepler, which both Crabtree and Horrocks accepted and Gascoigne under Crabtree’s influence came to accept. It was through this correspondence that we have Crabtree’s account of Horrocks’ death.
All of this might have been lost following the deaths of Horrocks (1641), Gascoigne (1644) and Crabtree (1644) if not for the Towneleys. When the Royal Society announced Auzout’s invention of the micrometre screw gauge in 1666 it was Richard Towneley (1629–1704), Christopher’s nephew and a mathematician and astronomer in his own right, who piped up and said I beg to differ. John Flamsteed (1646–1719) (another northerner, later to become the first Astronomer Royal, who was a protégée of Jonas Moore (1617–1679), yet another Lancastrian and a pupil of William Milbourne) travelled up north to investigate Towneley’s claims. Towneley demonstrated his micrometer screw gauge based on Gascoigne’s design to Flamsteed and the two of them travelled to Salford where Crabtree’s widow gave them the Crabtree Gascoigne correspondence. Flamsteed made notes from the correspondence but the originals remained in the possession of the Towneley family.
Robert Hooke drew diagrams of Towneley’s version of Gascoigne’s micrometer, which were published in the Philosophical Transactions of the Royal Society thus establishing Gascoigne’s priority and his right to be acknowledged the inventor of the micrometer screw gauge.
As a small side note it was Richard Towneley together with Henry Power (1623–1668) who first discovered what is now known as Boyle’s Law, which Power published in his Experimental Philosophy, in three Books in 1664, an important early work on microscopy and the corpuscular theory.
Much of Gascoigne’s original correspondence has become lost of time but enough has been recovered to give a vivid picture of this inventive and highly skilled astronomer and his contributions to the history of astronomy. More important the fragments of the Gascoigne story demonstrate very clearly that progress in science in not achieved through lone geniuses but through networks of researchers exchanging views and discoveries and encouraging each other to make further developments.