Geometrical rules made easy for the use of mechanicks concern'd in buildings [electronic resource] : Containing, New and Infallible Methods, for Striking out from proper Centers, the Groyns of Arches regular and irregular, the Angle Brackets of Coves, Crowns of Beaufets circular or elliptick. With many other useful Problems relating to all Curve Lines, introduc'd in Building. Also, an essay, on the nature and properties of arches in general, mechanically consider'd with Respect to their Shapes and Duration, exemplified by several Geometrical Figures, demonstrating their Property and Powers, interspersed with some Remarks on the intended Bridge at Westminster. With a Proposal for Building the Piers, by a Method practicable, so as to keep out the Water while erecting. The Whole design'd chiefly for the Information and Use of all Building Artificers, &c. By Isaac Gadsdon.