The description and use, of a new constructed octant, sextant and quintant : By His Majesty's patent, being an improvement on the Hadley's quadrant. By either of which, altitudes are taken, and angular distances measured to the greatest precision from 0. to 160ʻ. Without a back observation, and with double the space of illumination, or field of view: also a new meth[o]d of adjusting the glasses, and applying the instrument for the purposes of finding the latitude and longitude at sea.. By G. Wright.