Letter, from Antoni van Leeuwenhoek to the Royal Society, dated at Delft Signed autograph Observations of crystals from calcite, gypsum, rock crystal, chlorite and tourmaline Original figures no longer exist Read to the Royal Society on 3 July 1705 English translation see EL/L3/82 Transcribed and translated in 'Alle de brieven van Antoni van Leeuwenhoek', edited, illustrated and annotated by Committee of Dutch Scientists, vol 15, p 207 English translation printed in 'Philosophical Transactions', vol 24, no 298, p 1906 25 May 1705