Elements of Descriptive Geometry

From the PREFACE. This book, like its companion volume, "Elements of Drawing" by the same authors, is based on the work of this character required of all first-year students in Sibley College, Cornell University. It is the outgrowth of an effort to modify and shorten somewhat the scope and method of presentation of this subject, from the lengthy discussion often presented, to one more in keeping with the relative importance of the subject in an engineering curriculum. This work was undertaken for me some years ago by Professor Blessing, and the book is the outgrowth of a series of lectures and an accompanying drawing-room course first given by him and later continued by Professor Darling; both being at the time members of the instructing staff of the Department of Machine Design and Construction of Sibley College. The work of putting this material into the form of a book was undertaken by the authors at the writer's request, the object in view being twofold, namely: to obtain a book exactly suited to the needs of the Department, which we had hitherto been unable to do, and also to put into permanent shape the methods and principles used in this work, thus forming one of a series of correlated textbooks which eventually it is expected will cover the entire work of the Department. The authors brought to the task a full knowledge of the more advanced work of the Department, having had experience in teaching the advanced subjects in design, which with their experience elsewhere both in practical and teaching positions was of great aid in improving and simplifying this more elementary work. For five years this material has seen used in mimeographed form in this and other institutions with such unqualified success as to warrant the belief that the methods of presentation are sound and the scope sufficient to give the student all the training and information necessary to pursue advanced work in drawing and design, without omitting any essential details necessary in training engineering students. The following suggestions by the authors as to the use of the book may make their point of view clearer: "The presentation of an experiment as a means of bringing out fundamental principles has been found to appeal to the student and it has enabled many to grasp the subject with comparative ease who had considerable difficulty by other methods in 'visualizing' these simple problems. For the average student the mere reading of the experiment is sufficient but others may require the actual 'building up' of the experiment to fully grasp the principles involved. The analysis and solution of each problem should be thoroughly understood and, as a test of the thoroughness and accuracy, the solution of the 'check' will serve....