Thomas Harriot's "Artis analyticae praxis" is an essential work in the history of algebra. This is the first English translation of his work, first published in Latin in 1631. It has recently become clear that Harriot's editor substantially rearranged the work, and omitted sections beyond his comprehension. Basing their work on manuscripts in the British Library, Pentworth House, and Lambeth Palace, the commentary contains some of Harriot's most...