The longitude discovered by the eclipses [electronic resource] : occultations and conjunctions of Jupiter's planets. With descriptions of those Refracting and Reflecting Telescopes; and of those Sectors, and that Quadrant, which are the Instruments necessary for this Discovery, both at Land and Sea. To which is added, An Ephemeris for the latter Half of the year of our Lord 1738. Containing the Configurations of Jupiter's Planets at Six a Clock every Evening, while Jupiter is to be any where seen. With those Eclipses, Occutations, and Conjunctions that are useful for the Discovery of the Longitude, both at Land and Sea. Engraven on a Copper Plate. Humbly Recommended to The Honourable the commissioners appointed by Act of Parliament for the Discovery of the Longitude at Sea. By Will. Whiston, M. A. Sometime Professor of the Mathematicks in the University of Cambridge.