Most mathematicians' knowledge of Euclid's lost work on Porisms comes from a very brief and general description by Pappus of Alexandria. While Fermat and others made earlier attempts to explain the Porisms, it is Robert Simson who is generally recognised as the first person to achieve a genuine insight into the true nature of the subject. In this book, Ian Tweddle, a recognised authority on 18th century Scottish mathematics, presents for the first time a full and accessible translation of Simson's work. Based on Simson's early paper of 1723, the treatise, and various extracts from Simson's notebooks and correspondence, this book provides a fascinating insight into the work of an often-neglected figure. Supplemented