Navigation improved : In two books. Book I. Containing an exact description of the fluid quadrant for the latitude; or, Quadrants reduc'd to the utmost degree of portableness: whereby quadrants of a small radius are contriv'd to be equally useful, and as exact as the largest quadrant now in use. By which travellers and others, with these protable instruments, may be able to take any observations, on land or sea, to greater exactness than with the largest quadrant yet invented. Design'd for the further improvement of astronomy, and the correction of table belonging thereto. Of principal use at sea, in finding the latitude of places, when the horizon is any way obscured, to the same exactness as in the clearest weather; and also by the fix'd stars, with the same certainty as by the sun: whereby there will be more frequent opportunities for finding the latitude, when no other instrument can be of service. Book II. An essay on the discovery of the longitude, by a new invention of an everlasting Horometer. Founded on the most unerring principles of nature. With copper plates of the instuments, &c. By Captain Jacob Rowe.