A key to the modern sliding-rule. Containing the description and exlpanation [sic] of the various purposes, of that valuable instrument, as now used by His Majesty's officers of customs, excise, &c. and also of two improved sliding-rules, for speedily and accurately gauging and measuring solids and superfices at one operation. Not to be performed by any other instrument yet constructed. Together with the advantages of a new instrument of sliding sines and tangents in plane and spherical trigonometry. By the Rev. W. Flower, projector of the said instruments.
