The marrow of the mathematicks : contracted into a small compass, and made plain and easie to the understanding of any ordinary capacity. Containing the doctrines of arethmetick, geometry, astronomy, gauging, the use of the sector, surveying, dyalling, and the art of navigation, &c. Illustrated with several cuts for the better explanation of the whole matter. After a new, compendious, easie method, by W. Pickering, merchant-adventurer. Licensed Octob. 9th 1685. Rob. Midgley