IRON AND STEEL: a Work for the Forge, Foundry, Factory, and Office. Containing Information for Ironmasters and their Stocktakers ; Managers of Bar, Rail, Plate, and Sheet Rolling Mills; Iron and Metal Founders; Iron Ship and Bridge Builders ; Mechanical, Mining, and Consulting Engineers; Architects, Builders, etc. By Charles Hoare, Author of 'The Slide Rule,' etc. Eighth Edition. Oblong 32mo, 6s., leather. " For comprehensiveness the book has not its equal." - Iron.

## Comprehensive Weight Calculator

THE WEIGHT CALCULATOR, being a Series of Tables upon a New and Comprehensive Plan, exhibiting at one Reference the exact Value of any Weight from 1lb. to 15 tons, at 300 Progressive Rates, from I Penny to 168 Shillings per cwt., and containing 186,000 Direct Answers, which, with their Combinations, consisting of a single addition (mostly to be performed at sight), will afford an aggregate of 10,266,000 Answers ; the whole being calculated and designed to ensure Correctness and promote Despatch. By Henry Harben, Accountant, Sheffield. New Edition. Royal 8vo, 1l. 5s., strongly half-bound.

## Comprehensive Discount Guide

THE DISCOUNT GUIDE : comprising several Series of Tables for the use of Merchants, Manufacturers, Ironmongers, and others, by which may be ascertained the exact profit arising from any mode of using Discounts, either in the Purchase or Sale of Goods, and the method of either Altering a Rate of Discount, or Advancing a Price, so as to produce, by one operation, a sum that will realise any required profit after allowing one or more Discounts : to which are added Tables of Profit or Advance from 1¼ to 90 per cent., Tables of Discount from 1¼ to 98¾ per cent., and Tables of Commission, etc, from ⅛ to 10 per cent. By Henry Harben, Accountant. New Edition. Demy 8vo, 1l. 5s., half-bound.

## Mathematical Instruments

MATHEMATICAL INSTRUMENTS: Their Construction, Adjustment, Testing, and Use ; comprising Drawing, Measuring, Optical, Surveying, and Astronomical Instruments. By J. F. Heather, M.A. Enlarged Edition. 12mo, 5s. cloth.