The Description and Use of that Most Excellent Invention Commonly Call'd Mercator's Chart ; with Some Observations, Useful for the Better Understanding the Nature Thereof: to which is Added the Description of a New Scale, Whereby Distances on a Given Course May be Measured, Or Laid Off, at One Extent of a Pair of Compasses ; which Renders this Chart as Easy in Practice as the Plain Chart: Also a Letter to Dr. Halley, Concerning the Globular Chart. By Thomas Haselden ; Late Teacher of the Mathematicks, to His Majesty's-Volunteers, in the Royal Navy