Letter, from Antoni van Leeuwenhoek to Hans Sloane, dated at Delft Concerning the quality of magnifying glasses; observations of the cornea, blood vessels, and small particles (crystalline humour) in Leeuwenhoek's eye Read to the Royal Society on 9 July 1701 English translation see EL/L3/34 Transcribed in JBO/10/224 Transcribed and translated in 'Alle de brieven van Antoni van Leeuwenhoek', edited, illustrated and annotated by Committee of Dutch Scientists, vol 13, p 367 English translation printed in 'Philosophical Transactions', vol 22, no 273, p 903 21 June 1701