vi PREFACE 
to the exercises beforehand, but such teachers may, if they choose, make 
simple alterations in the data of the exercises before giving them to their 
students, and thus in an easy way have their own set of good exercises. 
The answers given at the end of the book will, however, be useful to 
students who may be studying privately, and also to conscientious and 
industrious students who may desire to get thoroughly familiar with the 
subject by working examples. 
The three chapters on the design of structures have been written and 
illustrated, on lines suggested by the author, by Mr. E. H. Salmon, B.Se. 
(Lond.), A.M.Inst.C.E., and the author feels that these chapters will add 
very considerably to any merit which the other chapters may give to the 
book. 
To Mr. J. W. Barrett the author is deeply indebted for the great care, 
intelligence, and skill which he has bestowed on the preparation of the 
illustrations from the author’s pencil drawings and sketches. 
A good and enthusiastic teacher interested in his subject does not as 
a rule follow strictly any particular text-book, not even if he has written 
it himself, and many of the best teachers seldom refer to any text-book 
in their lectures. It is, however, very important that a student should 
form as good a library of his own as he can afford, and the author of this 
book hopes that it will not be unworthy of a place in such a library, 
especially in the initial stages of its formation. 
D. A. L. 
East LONDON COLLEGE (UNIVERSITY OF LONDON) 
September 1909. 
