Sir John Pettus (1613-1690), British metallurgist, at the age of 70. This engraving is taken from Pettus' book, a translation of The Laws of Art and Nature, in Knowing, Judging, Assaying, Fining, Refining and Inlarging the Bodies of Confin'd Metals (1683), by Lazarus Erckern, the Assay- Master General of the Empire of Germany. This work, which was written while Pettus was imprisoned for debt in London, is considered the first manual of analytical and metallurgical chemistry. Before being imprisoned, Pettus was the Deputy Governor of Royal Mines for over 35 years.