It has been my lot, during a long and eventful passage through life, to have my attention forcibly drawn to a multitude of Mechanical Subjects; the present review of which permits me to hope, that in making them publicly known, I should render an important service to the Arts and to Society. But the manner of doing this has been so long a question with me, that I have sometimes feared my ability would be extinct before I could do it at all. The reasons, however, that urge me to make the attempt acquire strength with the lapse of time: and whenever my declining health bespeaks the approach of that “night in which no man can work,” I feel deep regret, that this tribute should not have been thrown into the treasury of human knowledge while yet, by the favour of a good Providence, the means of doing it were more fully at my disposal. I have determined therefore to publish these Inventions. Not because they have been matured into a regular System of Mechanical truth; but because they consist of many distinct objects of immediate application:—coupled with some ideas of a more comprehensive nature, that may probably extend the usefulness of this admirable study, in the hands of Artists yet unborn. The form, or rather the title of this work, has but one example, that of the illustrious Marquis of Worcester; whose name may, perhaps, prolong the remembrance of mine: an event the rightful anticipation of which, I confess, would give me pleasure. Not that I either covet or regard what is commonly called popular applause: but the approbation of the wise and good I do regard, and aspire to obtain; since that alone seems to fulfil the adage—“Vox populi vox dei.” On the subject of our respective Inventions, my views are somewhat different from those of the Noble Marquis; whose description of his labours, as the custom then was, seems chiefly calculated to excite the desire of knowing them better: whereas my wish is to infuse, at once, the knowledge of my subjects into every head capable of receiving it. This Work then, treats less of Theory than Practice. What are called Principles in Mechanics, are, and must be, founded on numerous suppositions; to present which to “the mind’s eye” requires often a forest of signs, which some readers will not, and others can not penetrate; so that, for many, Theory might as well not exist. This evil is increased when, as it sometimes happens, these suppositions are laid so far from reality, as to leave the result, though correctly deduced, further from the truth than the point to which a sound understanding unassisted by science, would have carried it. To this extreme discrepance of views between theoretical and practical men, may be ascribed their well-known antipathy to each other—in indulging which, they are alike to blame! since no theory inconsistent with fact can be complete; nor any fact be adduced, that a perfect theory will not account for and confirm. Happily these discussions do not affect my present purpose. For although I shall offer nothing contrary to sound theory, I do not consider that as my subject; but make it my business to present rational methods of producing useful effects.—In other words to describe these Inventions as connected with immediate Practice. And if, hereafter, it should become desirable to resume the discussion of any principle relating to these subjects, I shall cheerfully enter upon it; but hasten, mean while, to do what seems more important—to place the subjects themselves beyond the danger of being wholly lost, whatever may befall me in the course of those events which are still among the secrets of Heaven.