Engraving of Robert Boyle’s ‘pneumatical engine’ in New Experiments Physico-Mechanicall, Touching the Spring of Air (London, 1660). The air-pump or vacuum chamber, designed and constructed in 1659 by Robert Hooke (1635–1703), was used for a pneumatic test (performed in the Royal Society in mid-July 1663) which is described in a letter by Oldenburg to Spinoza (10 August 1663).