PKEFACE 



In presenting this book the authors believe that its title sufficiently 

 indicates its purpose and scope. It may be well, however, to add a 

 few words on certain features to which it is desired to call special 

 attention. 



In order to provide for the needs of both class room and laboratory 

 the book has been divided into two parts, the first part presenting 

 the theoretical side of the subject and the second part its experi- 

 mental side. By this means it is believed that a closer correlation of 

 laboratory and class work may be secured, and also that the student 

 will obtain a more effective knowledge of the subject and the book 

 prove a more valuable addition to his professional library. 



The mechanics of materials, as ordinarily presented, differs essen- 

 tially from the mathematical theory of elasticity, in that the former 

 is concerned with the development of special rules applicable to the 

 structural forms in common use, whereas the latter deals with the 

 general relations between stress and deformation in an elastic solid, 

 irrespective of its size or form. While special rules may be sufficient 

 in most cases, the student should have some knowledge, at least, of 

 the general fundamental principles upon which they are based, in order 

 that he may be in a position to treat new problems as they arise. 

 With this in mind, the first two chapters have been devoted to a gen- 

 eral discussion of the relations between stress and deformation, and 

 t> the demonstration of certain elementary theorems which serve as 

 a basis for the special rules of calculation subsequently developed. 



In the analytical treatment of the subject the aim has been to give 

 a systematic development, combining rigor with simplicity. In 

 accordance with this purpose such fundamental ideas as Hooke's law 

 and Bernoulli's assumption have been given in detail, and sp<j ^ial 

 emphasis placed on the limitations to their validity. It may also be 

 noted that the moment of inertia is presented as the shape factor in 



,ITY OF TORONTO 



CIVIL EN.dTNEer 



