Little is known of Penkethman save that he was a book-keeper and Latinist active in London in the 1620s and 1630s. He had a good knowledge of mathematics, Latin and history, so presumably was well-educated. His profession was that of book-keeper or accountant, but he also translated works by Cato and Virgil into English verse. Among his later achievements were a concordance of all male and female Christian names in England with their Latin equivalents, and a set of tables showing all the gold coins in circulation with their proper weights.
From The Biographical Dictionary of British Economists in Oxford Reference.