PREFACE. V 



of the old edition, as it was thought there was not a logical 

 reason for dividing the chapter. An explanation of How's 

 notation is added and several of the graphical solution- have 

 been redrawn using this notation. A new article on the derrick 

 is also added. 



There has been little alteration in old chapters VII, VIII, 

 IX and X, except in the chapter numbers. 



Old Chapter XI has been expanded into two chapters, 

 Chapter X on Roof Trusses, and Chapter XI on Bridge Trusses. 



In Chapter XII, on Stresses from Uniform Load, solutions 

 have been added for the deck Pratt, sub-divided Warren, Whipple 

 and Pettit trusses, and skew bridges. 



In Chapter XIII a complete solution of the stresses in a 

 Pratt truss railroad bridge from wheel loads is added and a 

 moment table is given for Cooper's loading. 



In Chapter XIV a more complete explanation is given of 

 the solution of the stresses in bridges with curved track. 



Many of the figures have been redrawn and a large number 

 of new ones added. 



CLYDE T. MORRIS. 



COLUMBUS, O., 



March, 1916. 



Acknowledgment is due from the Publishers to Mr. C. T. 

 Morris, Professor of Structural Engineering, Ohio State Uni- 

 versity, for the valuable work done by him in the preparation for 

 the press of Professor Heller's manuscript. 



