“Only let men awake, and fix their eyes, one while on the nature of things, another while on the application of them to the use and service of mankind.”--_Lord Bacon._ _Extract of a Letter from_ WALTER R. JOHNSON, _Professor of Mechanics and Natural Philosophy in the Franklin Institute_. “This treatise is intended and admirably calculated to supply the deficiency in the means of mathematical instruction to those who have neither time nor inclination to peruse numerous abstract treatises in the same departments. It has, besides the claims of a good elementary manual, the merit of embracing several of the most interesting and important departments of Mechanics, applying to these the rules and principles embraced in the earlier sections or the work. “Questions in Statics, Dynamics, Hydrostatics, Hydro-dynamics, &c. are treated with a clearness and precision which must increase the powers of the student over his own intellectual resources by the methodical habits which a perusal of such works cannot fail to impart. “With respect to Engineering and the various incidents of that important profession, much valuable matter is contained in this volume; and the results of many laborious series of experiments are presented with conciseness and accuracy.” _Letter from_ ALBERT B. DOD, _Professor of Mathematics in the College of New Jersey_. “Messrs. CAREY & HART, “Gentlemen--I am glad to learn that you have published an American edition of Dr. Gregory’s ‘Mathematics for Practical Men.’ I have for some time been acquainted with this work, and I esteem it highly. It contains the best digest, within my knowledge, of such scientific facts and principles, involved in the subjects of which it treats, as are susceptible of direct practical application. While it avoids such details of investigation and processes of mathematical reasoning as would render it unintelligible to the general reader, it equally avoids the sacrifice of precision in its statement of scientific results, which is too often made in popular treatises upon the Mathematics and Natural Philosophy. The author has succeeded to a remarkable degree in collecting such truths as will be found generally useful, and in presenting them in an available form to the practical mechanic. To such, the work cannot be too strongly recommended; and to the student, too, it will often be found highly useful as a book of reference. “With much respect, “Your obedient servant, “ALBERT B. DOD, “_Professor of Mathematics in the College of New Jersey_. “Princeton, Nov. 11, 1834.” _Extract of a Letter from_ EDWARD H. COURTENAY, _Professor of Mathematics in the University if Pennsylvania_.