A GREAT VARIETY OF THE MOST USEFUL RULES IN DIVESTED OF MATHEMATICAL COMPLEXITY; WITH NUMEROUS TABLES OF PRACTICAL DATA AND CALCULATED RESULTS, MECHANICAL TABLES FOR THE USE OF OPERATIVE SMITHS, AND PRACTICAL DIRECTIONS FOR THE SMELTING OF METALLIC ORES. LONDON: JOHN WEALE, HIGH HOLBORN. 1855. 187.2.12. TO THE PUBLIC. THE subjects of the following pages are chiefly compiled at the instigation of pressing solicitations. by numerous individuals, no few of whom complain of the want of a convenient Text Book of Reference in which Mechanical and Commercial demands are judiciously combined. Others, with apparently equal reasons, for the sake of instruction, complain of the want of a compendium in which tuition and practical reference are discriminately arranged; and generally, that for purposes of estimation, no properly portable work is yet in existence; hence it is with a wish to diminish those wants in some degree that the present attempt has been made to supply the necessary information. In regard to the selection, great care has been taken that the subjects be not only intimately interwoven, but also of such a nature as business transactions call most frequently into requisition. The elementary or educational portion will be found exceedingly plain, simple, and aptly adapted; also the practical rules much abbreviated through the application of decimal approximates, by which results iv are obtained sufficiently exact, and the means of calculation considerably facilitated. That the production might be rendered still more worthy of public patronage, numerous diagrams, and several engravings, are annexed, which add much to its value in regard to practical utility; and it only remains to add the hope, that the Operative, the Man of Science, and an interested Public, may give due appreciation to the work, in proportion to its merits. W. T. The present edition has been much extended by the insertion of numerous Tables for the use of Operative Smiths, Millwrights, and Engineers, and by a further addition of Practical Observations on the Smelting of Metallic Ores. May, 1855. CONTENTS. To erect a perpendicular on a right line To erect a perpendicular at the end of To bisect a given angle To describe a circle through three given To find the centre of a given circle To find the length of any given arc of a To draw lines towards the centre of a To describe an arc of a circle To describe an ellipse or oval To measure an intercepted line To obtain the distance of an inaccessible To find the distance between two inac- cessible objects . 11 |