SummaryA letter in which astronomer John Flamsteed expounded his unusual views about the causes of earthquakes survives in a number of drafts and copies. Though it was compiled in response to shocks felt in England in 1692 and Sicily in 1693, its relationship to the wide range of comparable theories current in the later seventeenth century must be considered. Flamsteed's suggestion that an ‘earthquake’ might be an explosion in the air was linked with contemporary thinking about the roles of sulphur (...) and nitre in earthquakes underground, and in combustion, respiration, and other processes. It reveals his concern with subjects other than astronomy and the influence of his continuing contact with members of the Royal Society; it also offers an early example of how seventeenth-century work on sulphur and nitre prepared the way for ‘airquake’ and electrical theories associated with the London earthquake of 1750. (shrink)

One of Ole Römer's most influential contributions to astronomy was the theory that light has a finite speed, which he calculated from inequalities in the motion of a satellite of Jupiter. The English astronomer John Flamsteed, first director of the Royal Observatory at Greenwich, is credited with being an early and influential supporter of the theory. This article examines how he came to be so, taking issue with the claim that he was instantly converted to the idea by a personal (...) encounter with Römer. The publication of Flamsteed's Correspondence has made illuminating material newly accessible; through letters it is possible to track the gradual development of his thinking and how it related to his dealings with Römer and with Giovanni Domenico Cassini (director of the Paris Observatory). The resulting account offers new insights into their attempts to share information, in a situation where motives for collaborating were counterbalanced by a potential for rivalry and conflict, and into the interlinked roles played by written correspondence, personal meetings and empirical investigation in the spreading of new ideas. (shrink)

This paper reports the experience of reconstructing a surveying instrument—the plane table—using the description found in Arthur Hopton’s Speculum topographicum: or The topographicall glasse : ‘Of the Plaine Table, with a description thereof, and the parts thereunto belonging’. One of the most detailed early printed descriptions of the instrument, it is illustrated with woodcut diagrams of components but no image of the complete plane table. The reconstruction process did not prove entirely straightforward. An examination of its various stages reveals how (...) Hopton’s text set out to persuade and lead the reader, rather than issuing orders to be followed exactly; the reader, left to make some decisions himself, would thus create a plane table with an element of uniqueness in its character. The role of the maker of such an instrument, even when following written instructions, was a creative and collaborative one, rather than purely passive.Keywords: Reconstruction; Instrument; Diagrams; Text; Instrument-maker; Collaboration. (shrink)

The use of mathematical and astronomical instruments played an important part in the development of Jonas Moore's career. Though debates about the nature of mathematics raised questions about the value of instruments, they remained essential to his work as a teacher, as Surveyor of the Fens and as Surveyor-General of the Ordnance. His confidence in them was most fully expressed in his equipping of the Royal Observatory and in his textbook for Christ's Hospital Mathematical School. His belief in the inseparability (...) of mathematical practice from theory meant that, for him, instruments continued to offer a means of putting certain knowledge into practical effect. (shrink)