London, The Royal Society, 1786. 4to (22.7 x 17.4 cm). 19 pp.; one large folded plate. Disbound.

A noteworthy contribution by Josiah Wedgwood (1730-1795) ‘Potter to Her Majesty’, founder of the Wedgwood company and a close friend of Erasmus Darwin, grandfather of Charles Darwin. He himself was father of Charles Darwin’s mother, Susannah Wedgwood. This study was prompted by Wedgwood's desire to improve methods of producing pottery for which an accurate measurement of high temperatures is essential. In an earlier paper, he described his invention, the pyrometer and the present work elaborates on this. Published in the Philosophical Transactions, volume 76. Small old stamp not touching figures on the plate, some light spotting, otherwise a very good wide-margined copy. Rare.