X PREFACE TO FIRST EDITION. 



the Appendix lu i will find detailed examples calculated to illus- 

 trate every practical point of importance, and also a full expo- 

 sition of Ritter's " method of moments?' The principles of 

 this chapter alone will enable him to solve readily, both by cal- 

 culation and diagram, every case usually arising in practice. 

 In problems involving the moment of inertia of areas in the 

 case of the continuous girder, the braced arch and stone arch, 

 as also the suspension system, he will find Chaps. VI., XII., 

 XIII., XIV. and XVI. of value, and in the perusal of any or 

 all of these he will, it is hoped, find no trouble by reason of 

 logical connection with preceding principles. They are in this 

 respect, as far as possible, complete in themselves. We may 

 also call his attention to Chap. XV., upon the stone arch, 

 though it is to be regretted that the practical importance of the 

 subject in the present age of iron renders the ease with which 

 it is graphically treated of less importance than formerly. For 

 his benefit also frequent practical examples are given in detail, 

 so that in all important applications he can easily select a 

 parallel case, and follow it out, step by step, in the case in 

 hand, without studying up the whole process of development 

 in order to place himself in a condition to make use of the 

 methods employed. In regard to the subject of the endurance 

 of iron, the student is referred to the author's translation of the 

 work, by Prof. Jacob J. Weyrauch already alluded to, of the 

 Polytechnic School in Stuttgart, issued by the publishers of 

 " Graphical Statics." "Weyrauch's book treats of the strength, 

 dimensions, and calculations of iron and steel, and being thor- 

 oughly practical, is heartily commended to the student, and 

 the profession of engineers generally. 



For the student much of the practical applications may well 

 be at first omitted. Notably Chaps. VII.-XIL, inclusive. 

 Chaps. I.-IV. and XIII.-XVI. will put him in complete pos- 

 session of the method, and, moreover, enable him to solve with 

 ease any structure, including the continuous girder, braced 

 arch, suspension system, and stone arch, as well as all the more 

 ordinary forms of bridge and roof trusses, cranes, etc. Indeed, 

 if the first-named structures, which are of comparatively rare 

 occurrence, are at first omitted, Chaps. I.-IV. alone will con- 

 stitute a complete course upon framed structures so far as 

 usually taught in our schools at the present day. Afterwards, 

 in practice, and in the solution of the particular problems 



