PREFACE.

THE peculiar character of the volume now submitted to the scientific world imperatively demands a full account of the views which have led the author to adopt the system of arrangement pursued in the following pages.

The great number of works hitherto published on the various branches of mechanical engineering may generally be classed under two heads-viz., elementary works, describing the general principles and forms of steam-engines, and complete treatises, including detailed descriptions, scientific disquisitions, and rules for calculating the proportions of various machines; the latter class also occasionally touching upon manufactures. There appeared, however, to be a very obvious chasm in the literature of mechanical engineering, some treatise being required possessing the following qualifications:

Practical method, portability, conciseness, and the exclusion of all unnecessary matter; the subject-matter comprising all the general operations connected with mechanical engineering, the scientific principles and examples illustrating the present condition of mechanical engineering. In the hope, therefore, of supplying to practical engineers and to students such a work the present treatise has been written.

The account of the processes which constitute the manufacture of iron commences with an introduction setting forth the natural condition of the minerals from which the metals of commerce

are derived, and enumerating the operations conducted in the

factory.

In the first chapter, the metallurgy of iron, copper, lead, tin, and zinc is considered; the nature and localities of the various metalliferous ores being described, and also the practical methods most usually employed for the reduction of metals to the conditions in which they occur in commerce; the apparatus required, and the principles upon which their action depends, and the mode of working them being also included.

Then follows a description of the various processes of forging and of the instruments used by the smiths. After which the construction of patterns, the methods of forming moulds of various kinds, and of casting metals, are discussed.

The form and action of the cutting-tools of the engineer have been carefully detailed, a thorough knowledge of the requirements which must be satisfied, in order to secure their correct action, being most important, though a proper appreciation of the forms of the principal machine tools is scarcely less necessary; wherefore some sound examples of turning-lathes, shaping, slotting, drilling, planing, and other machines, have been illustrated and described. As a sequel to the foregoing descriptions, an account of workshop manipulation is given, so far as it admits of description.

The physical basis of the steam-engine is next considered, the more refined methods of analysis being avoided, so as to retain a strictly practical character. Dr. Joule's equivalent for the calculation of the amount of work to be obtained from a given quantity of heat is inserted, forming, as it does, a convenient means for the expression of quantities of heat. But it is derived from experiments upon the amount of heat generated by friction of liquids; and, therefore, the author does not feel justified in considering its application to thermo-motive engines demonstrated, the facts extant being insufficient for this purpose. Stimer's and Isherwood's

experiments on the practical utility of using steam expansively have also been discussed at some length.

In the chapter on the Principles of Mechanical Construction, an attempt has been made so to generalize the theory of the action. of levers, hydrostatic presses, &c., as to replace by a simple calculation, easily remembered and applied, the numerous rules and formula which have hitherto been so abundantly supplied for levers, divided into various orders, and for other machinery, and which, being generally given without any notice of the reasoning upon which they are based, cannot be remembered, and frequently serve but to confuse the reader. The laws of falling bodies of rotatory motion, &c., are also explained.

The general forms of steam-engines, and principles of steamboilers, and qualifications of various kinds of engines are briefly treated, followed by lengthy accounts of the form and manufacture of each principal element of the steam-engine, after which the form, action, and manufacture of various kinds of pumps and valves are treated.

Practical formula for the length of boilers, descriptions of various kinds of boilers, and of the modes of constructing them, also accounts of the paddle-wheel, screw, and hydraulic propellers, with miscellaneous remarks upon some of the applications of steam-power, have also received due attention; and particular stress is laid upon the necessity of having reliable experiments upon steam-engines, and attention is drawn to the inferiority of modern engines in point of economy. It is indeed a fact much to be regretted, that notwithstanding the researches of scientific men, and the labors of practical engineers, no improvements have been made in the economy of the steam-engine since 1845. The remainder of the work is occupied by descriptions of examples of pumping, rotative, marine, locomotive, traction, and steam fireengines, concluding with a Glossary of the technical terms used throughout the work.

As in the account of the metallurgy of iron notice has been taken of the effects of various foreign ingredients with which the iron of commerce is always more or less contaminated, it has been thought advisable to add an Appendix, containing the various methods of analyzing chemically the various ores of iron and specimens of iron, so as to enable those who may feel disposed to examine for themselves such samples as may come under their notice.

The examples of the machinery illustrated have been carefully selected, and every means taken to secure correctness of the Plates.

The thanks of the Author are due to many scientific gentlemen who have assisted him with plans and information; especially to Thomas Wicksteed, Esq., for the plans of the large pumpingengine at the Grand Junction Water-works, designed by him in 1845; the Bolton-and-Watt pumping-engine at the East London Water-works, erected in 1829; Cornish boiler now erecting at the Scarborough Water-works; also for valuable information concerning the above, and the new pumping-engine now erecting at the Scarborough Water-works. To C. G. Gumpel, Esq., for plans of his hydraulic propeller, information concerning the same, and experiments performed for the Author's information upon the same. Also to Messrs. Pullan and Lake for plans of their new patent agricultural locomotive, and for the information respecting the same and their new traction engine.

WESTMINSTER,

January, 1863.