Letter, from Renatus Slusius to Henry Oldenburg, dated at Luttich Concerning a new book on geometry; account of the natural history of the area around Liege (eg climate, metals that are mined); that blood transfusions are carried out in Rome; concerning Boyle's experiments to show the nature of fluidity, solidity and precipitation Read to the Royal Society on 2 April 1668 29 March 1668