Francis Jessop (1638-91)

Naturalist and Mathematician

Lister met Francis Jessop in Montpellier, and continued to correspond with him throughout his life. Some of their joint work was published in the Philosophical Transactions of the Royal Society.

Jessop’s seat was Broomhall, a manor built outside Sheffield in the time of Henry VIII. He was a freeman of the Cutler’s Company of Sheffield, as well as a natural historian and mathematician. 1

The Royal Society printed his tract Propositiones Hydrostaticae ad illustrandum Aristarchi systema (1687), and Jessop engaged in a long and fairly fruitless dispute with mathematician John Wallis about cycloid curves; Wallis failed to realize that Jessop had discovered a means of rectifying the arc of an epicycloid. 2

Francis Jessop and John Ray also were fast friends. Ray stayed at Broomhall, using it as a base for his botanical expeditions and collaborative experimentation with both Jessop and Francis Willughby. The fruits of their labour were also published by the Royal Society, and Ray wrote about his visit with Jessop in a letter to Lister of 26 July 1668 (translation from the Latin):

My next halt was at Sheffield in Yorkshire. There I received a most kindly welcome from my old friend Mr. Jessop, in whose house I am still lodging. ‘What business did you have there?’ you will ask. I shall speak the truth. You know that I am dedicated to botany and have for some time been planning a native British flora. In order finally to finish this and complete it in every detail I am sparing no labours, even to the extent of undertaking long journeys in the summer months every year, even to the most distant counties of this realm, for as long as I can afford it, to track down plants. This summer I resolved to tour south Yorkshire and Westmorland, and I have now actually done this, after spending two weeks on the journey. . . .  From here I shall stay in Sheffield, where I intend to stay until the equinox.

Letter, 26 July 1668

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  1. W.H.G. Armytage, ‘Francis Jessop, 1639-1691: a Seventeenth Century Sheffield Scientist’, Notes and Queries 197 (2 August 1952), 343-346; Charles Raven, John Ray: Naturalist (Cambridge: Cambridge University Press, 1986), 35, 147-8. ↩
  2. Mordechai Feingold, ‘Isaac Barrow: divine, scholar, mathematician’, Before Newton:  The Life and Times of Isaac Barrow (Cambridge:  Cambridge University Press, 1990), 1-104, on 35. ↩

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