John Collins FRS (25 March 1625 – 10 November 1683) was an English mathematician. He is most known for his extensive correspondence with leading scientists and mathematicians such as Giovanni Alfonso Borelli, Gottfried Leibniz, Isaac Newton, and John Wallis. His correspondence provides details of many of the discoveries and developments made in his time, and shows his activity as an 'intelligencer'. Life He was the son of a nonconformist minister, and was born at Wood Eaton in Oxfordshire, 5 March 1625. Apprenticed at the age of sixteen to Thomas Allam, a bookseller, living outside the Turl Gate of Oxford, he was driven to quit the trade by the troubles of the time, and accepted a clerkship in the employment of John Marr, clerk of the kitchen to the Prince of Wales. From him he derived some instruction in mathematics, but the outbreak of the First English Civil War drove him to sea for seven years, 1642-9, most of which time he spent on board an English merchantman, engaged by the Venetians as a ship of war in their defence of Candia against the Turks. He devoted his leisure to the study of mathematics and merchants' accounts, and on leaving the service set up in London as a teacher. In 1652 he published An Introduction to Merchants' Accounts, originally drawn up for the use of his scholars. Reprinted in 1665, the major part of the impression perished in the great fire of London, but was replaced in 1674 by a new and amplified folio edition. He next wrote The Sector on a Quadrant, or a Treatise containing the Description and Use of three several Quadrants. Also an appendix touching Reflected Dyalling, from a Glass however posited (London, 1658); and The Description and Uses of a general Quadrant, with the Horizontal Projection upon it Inverted (1658). In 1659 appeared his Geometricall Dyalling, or Dyalling performed by a Line of Chords only, and The Mariner's Plain Scale new Plained, a treatise on navigation for the East India Company's navy. It was well received, and became a class-book with the students of navigation at Christ Church Hospital. After the Restoration, Collins was appointed successively accountant to the excise office, accountant in chancery, and secretary to the council of plantations, exchanging the last post in 1672 for that of manager of the farthing office. With this employment went a house in Fenchurch Street, where he