Print (mezzotint). Engraved by Peter Pelham after Hans Hysing, 1725; published by John Bowles, London. Titled ‘J. T. Desaguliers Legum Doctor, Regiae Societatis Londinensis | Socius, Honoratissimo Duci de Chandos à Sacris. Philosophiae Naturalis | Experimentorum ope Illustrator.’ The print is a half-length portrait of John Theophilus Desaguliers, shown seated at a table against a plain background. Facing to the left, he wears a wig and clerical dress. He holds a magnifying glass in one hand, and a prism rests on the table. Lettered underneath the image with title, and maker and publication details as follows: ‘H. Hysing pinx’; ‘P Pelham fec: 1725’; ‘Sold by John Bowles at the Black Horse in Cornhill’.

John Theophilus Desaguliers was allegedly smuggled in a barrel from France as a baby when his Protestant Huguenot parents fled religious persecution. He studied at Oxford and partly made a living in the Church, as indicated by his clerical attire in this portrait. The magnifying glass and prism with which he is shown, though, allude to his many scientific interests and occupations. He performed experiments at the Royal Society, lectured in natural philosophy, and promoted the complex ideas of Isaac Newton in a simplified way for those without advanced mathematical training. He also advised on numerous practical projects in London, like the construction of Westminster Bridge, although his own house had to be demolished to help make way for it. Many of Desaguliers’ publications are held by the Science Museum Library and Archives.