yet how few possess it, and how many will refuse to admit that it is essential to the successful practice of the mechanical and industrial arts! It cannot therefore be too frequently or too firmly asserted, that in order to advance the science of engineering, we must combine a knowledge of the first principles of the exact sciences with skill in construction; that a perception. of and acquaintance with the unerring laws which science reveals, is the only sound basis for creditable results; and with the view of encouraging the practical man in the pursuit of this knowledge, I have cited examples where industry and perseverance in the development and prosecution of more than one department of science and art have led not only to worldly success, but to honour and renown.

-

Metallic constructions open a wide field for investigation, and volumes might be written on this subject before it could be exhausted. On the present occasion, however, my observations have been confined to iron ship building, from the circumstances that I was among the first to take up this important branch of national industry, and embark in the construction of iron vessels upon a large scale. Nearly twenty years ago I made a series of experiments on malleable iron plates and rivets, the results of which were subsequently published in the Transactions of the Royal Society, and are now republished in the Appendix to the Lectures. These experiments, as well as those undertaken to determine the form and strength of the Britannia Tubular Bridge, apply with considerable certainty to almost every form of metallic construction, and have already been, I trust,

of great value in boiler making and ship and bridge building. In giving my views on this subject I have not attempted to offer an opinion on those forms of ships which come within the province of the naval designer, but have simply endeavoured to show in what position the material should be placed so as to attain the maximum of strength, in the general mass in its riveted form, as it appears in the iron ship.

In my attempts in the succeeding Lectures to investigate the nature and properties of steam, practically considered, I had to bring not only the whole of my experience and knowledge to the task, but I had to consult the writings of some of the most distinguished men of science since the days of Dr. Black, when he first announced his theory of latent heat.

It was not without great diffidence that I approached this question, inasmuch as the labours of such men as Black, Robinson, Watt, Southern, &c. in former days, and those of Arago, Dulong, Pambour, and Regnault of more recent date, made me sensibly alive to the difficulties which, in the present state of our knowledge, surround such an inquiry. I have referred, in the course of my investigations, to all these authorities; and although much has been accomplished in elucidation of the subject by these writers, there is, nevertheless, a wide field yet to be explored before our knowledge of steam, and its application as a moving power, can be said to be clearly and explicitly understood.

Viewing the subject in this light, I have not hesitated to direct the attention of the practical engineer to the new discoveries relative to the laws of elastic

fluids, contained in the researches of my friend Mr. Joule, Professor Thompson, and Regnault. To the investigations of those writers I am indebted for new and useful information.

On the employment and use of high-pressure steam, I have dwelt with more than ordinary attention: I have done so from a conviction that we have yet much to learn in relation to its application, retention, and improved expansion.

Unquestionably, considerable advances have been made within the last ten years in the construction of the steamengine; but we are still far from having attained a perfect construction either in the land, the marine, or the locomotive engine. It is true, that in our manufactories we are now performing almost double the work with the same quantity of fuel that was formerly performed; and nearly the same improvements and economy have been accomplished by the use of high steam on board our steamers; but we have still much farther to go, for by a careful and judicious application of high steam-in improved engines, probably working from 150 to 200 lbs. on the square inch, we may venture to look forward to a new and important era in the history of steam and the steam-engine.

I cannot conclude this Preface, already too long, without some words of acknowledgment to my friend Mr. Tate, for his able mathematical investigations, a labour

*The present war has led to the employment of high-pressure steam vessels in the navy, and I am glad to find that the steam department of the Royal Navy is now alive to the importance of using high steam in vessels of war. Vide a circular note just issued by the Admiralty at the end of the Appendix.

which has been cheerfully rendered on his part, and the value of which can only be appreciated by those who, like myself, have found his researches so highly advantageous. If I have reserved his name to the last of those to whom I am indebted, it is certainly not because I value his services the least.

In conclusion, I have to express my acknowledgments to the various Institutions with which I am connected, for the readiness with which they permitted me to avail myself of my contributions to their Transactions for republication; and I sincerely hope that the Volume now offered may be useful, not only to the Members of those Institutions, but to the wider circle of working engineers for whom it has been exclusively written.

MANCHESTER: Dec. 10, 1855.

W. F.

A TREATISE ON MILLS AND MILLWORK.

Second

VOL. I. The Principles of Mechanism and Prime Movers. Edition, carefully corrected: with 8 Plates and 176 Woodcuts. 8vo. price 16s.

A TREATISE ON MILLS AND MILLWORK.

VOL. II. Machinery of Transmission, and the Construction and Arrangement of Mills; with 10 Plates and 146 Woodcuts. 8vo. price 168.

ON

THE APPLICATION OF CAST AND WROUGHT IRON TO BUILDING PURPOSES.

Third Edition, greatly enlarged, with Corrections and Additions. To which is added, a short Treatise on Wrought Iron Bridges, with Additions, &c. With 6 Plates and 118 Woodcuts. 8vo. price 16s.

USEFUL INFORMATION FOR ENGINEERS, SECOND SERIES: Containing Experimental Researches on the Collapse of Boiler Flues and the Strength of Materials, and Lectures on Popular Education and various Subjects connected with Mechanical Engineering, Iron Ship-Building, the Properties of Steam, &c.

With Plates and numerous Woodcuts. Crown 8vo. price 10s. 6d.

London: LONGMAN, GREEN, and CO. Paternoster Row.