THE WILEY TECHNICAL SERIES FOR VOCATIONAL AND INDUSTRIAL SCHOOLS EDITED BY JOSEPH M. JAMESON GIRARD COLLEGE THE WILEY TECHNICAL SERIES EDITED BY JOSEPH M. JAMESON SHOP TEXTS NOW READY Practical Shop Mechanics and Mathematics. By By W. Cloth, Plain and Ornamental Forging. By ERNST SCHWARZKOPF, Instructor at Stuyvesant High School, New York. x+267 pages, 51 by 8, 228 figures. Cloth, $1.50 net. Mathematics for Machinists. By R. W. BURNHAM, Instructor in Machine Work, Pratt Institute Evening School. vii+229 pages, 5 by 7. 175 figures. Cloth, $1.25 net. Arithmetic for Carpenters and Builders. By R. BURDETTE DALE, Director of Vocational Courses, Iowa State College. ix+231 pages, 5 by 7. 109 figures. Cloth, $1.25 net. Tool Making. IN PREPARATION By W. J. KAUP, Crucible Steel Company of America, and J. A. CHAMBERLAIN, Supervisor of Manual Training, Washington, D. C. For full announcement see list following the index. 5M. 1-12-18 Teacher, Erasmus Hall High School, Brooklyn, N. Y.; FIRST EDITION NEW YORK JOHN WILEY & SONS, INC. LONDON: CHAPMAN & HALL, LIMITED 1915 t PREFACE IN an experience of more than ten years in teaching machine-shop work to evening classes of men and boys actually engaged in the trade, the author has observed a decided lack of mathematical knowledge among ordinary mechanics. Many leave school from the grammar grades. Any mathematical training that they once may have received is, therefore, so far behind them by the time they are well started in their trade that it has practically been forgotten. About all that has been retained is a fair understanding of addition, subtraction, multiplication and division. For such, the natural starting point for a further knowledge of mathematics is the study of fractions. Beginning with fractions, this book aims to give, in elementary form, an explanation of the calculations most frequently occurring in machine-shop work. The treatment has been made as simple as possible, in some places almost too simple, perhaps, with the desire to put the explanation in such a form as to be easily understood. Many mechanics are mistakenly impressed with the extent of their mathematical knowledge. If they are able to take some formula from a handbook and apply it by rule of thumb to a particular calculation they are called upon to make, they are entirely satisfied. Experience has shown that such knowledge is often so shallow that a mere change in the letters of a formula will so disguise its meaning that the mechanic fails utterly even to recognize 327231 iii |