Notices respect i?ig New Books. 43 



as it became known that he had such an object in view, he has con- 

 tinually received contributions of information from other engineers, 

 who wished to promote the undertaking j and, with very few excep- 

 tions, this feeling has been general in the profession. In this way 

 the author became personally acquainted with two great authorities 

 in this branch of mechanics, the late Mr. Watt and Mr. Woolf, and 

 received from them a full knowledge of the origin and progress of their 

 respective inventions, and of the principles which they followed in ap- 

 plying those inventions to useful practice. 



•' At the commencement of his professional studies in the years 1805 

 and 1806, the author felt the want of a guide of this kind j and after 

 carefully studying Dr. Robison's article in the Encyclopaedia Briton- 

 nica, and M. Prony's Architecture Hydraulique, and finding them in- 

 sufficient for that purpose, he determined to preserve notes of all the 

 observations and investigations, by which he should acquire his own 

 knowledge of the construction and principles of operation in steam- 

 engines and other machines, and their various applications ; in the 

 expectation that at some future period a useful publication might be 

 formed from those materials. Professional avocations have long since 

 occupied all the time which might have been devoted to such an ob- 

 ject, but it has never been abandoned j and if the sale of the present 

 work should prove sufficient to induce the publishers to undertake 

 others of a similar nature, the author has an accumulation of notes, 

 which in the course of years he may find time to arrange in a corre- 

 sponding form with the present work. 



" In the year 1815, the author drew up a descriptive article on the 

 steam-engine for Dr. Rees' Cyclopadia ; but the plan of that work, 

 and the limited number of engravings, rendered it necessary to avoid 

 details, which must constitute the great value of a practical treatise. 

 Since the publication of that article in 1816, the want of a correct 

 manual has been still more felt, from the great and increasing ex- 

 tension of the use of steam power, and the author was advised by his 

 friends in the profession to resume his original project j this he under- 

 took to do in 1820, and the bulk of the historical part was written, 

 and, most of the plates were engraved by the late Mr. Lowry, in the 

 next year ; but the author being obliged to reside at a distance from 

 London, by engagements which left no leisure for this object, the 

 impression has been carried on at intervals, and the publication of 

 the first volume has been unavoidably protracted until the present 

 time. 



" To instruct students, it is necessary to state such elementary pro- 

 positions in mechanics, as have a direct application to the subject of 

 steam-engines j for this purpose a series of definitions are given in 

 an Introduction to the present volume. These definitions have been 

 formed from a full examination of the works of the best writers on 

 the theory of mechanics, viz., Belidor, Emerson, Smeaton, Hutton, 

 Banks, Gregory, Robison, Young, and others. The author has en- 

 deavoured to preserve their modes of reasoning, and the mathemati- 

 cal accuracy of their conclusions, without employing the language of 



G 2 geometrical 



