An addition vnto the vse of the instrument called the circles of proportion, for the working of nauticall questions : Together with certaine necessary considerations and advertisements touching navigation. All which, as also the former rules concerning this instrument are to bee wrought not onely instrumentally, but with the penne, by arithmeticke, and the canon of triangles. Hereunto is also annexed the excellent vse of two rulers for calculation. And is to follow after the 111 page of the first part. - Oughtred, William, (Printed by Augustine Mathewes,, 1633)