A treatise of such mathematical instruments, as are usually put into a portable case. [electronic resource] : Shewing some of their uses in arithmetic, geometry, trigonometry, spherics, Architecture, Surveying, Geography, Perspective, &c. with an Appendix; Containing The Description and Use of the Gunners Callipers. And The Description of, and Precepts for the Delineation of, Ship-Guns and Sea Mortars. To this Treatise, is prefixed A Brief Account of Authors, who have wrote on the Proportional Compasses and Sector. The third edition, with many additions. By John Robertson, Librarian to the Royal Society.