IV PREFACE TO FIRST EDITIOX. 



until, as already iviiiarkt-d, they now form a notable feature in 

 the course of every technical institution in the land. 



The accept am-? which the method has found in France, and 

 the uttiMitii.ii which it has there excited, is sufficiently indicated 

 by the work of Levy (!M, Statique Graphique et sea Applied' 

 tions, Paris, 1874), which contains a very clear and elegant 

 presentation of the principles, though the applications are of 

 the simplest character, while, as was perhaps not unnatural in 

 the author, the German origin of the system is very imper- 

 fectly indicated, and the special methods of Culmann but little 

 more than hinted at. 



In Italy also the method has found an ardent expounder in 

 die distinguished mathematician Cremona (Le figure recip- 

 roche nette statica gra/fica, Milan, 1872), and to his efforts and 

 labors its introduction and acceptance is due. 



In England, Prof. Clerk Maxwell } in the Trans, of the Royal 

 Society of Edinburgh, 1869-70, has contributed a paper upon 

 " Reciprocal Figures, Frames and Diagrams of Forces/' and, 

 among others, Jeukin, Ranken, Bow, and Ur.win have contrib- 

 uted to the popularity and spread of " Maxwell's Method." 

 Maxwell and his followers give, however, only the very simplest 

 applications, based upon the resolution and composition of 

 forces, such as will be found in our first chapter. The entire 

 system developed by Culmann, the properties of the " equilib- 

 rium polygon," upon which the fruitfulness and value of the 

 graphical statics wholly depend, are unnoticed both by our 

 English and French authors. 



The author feels, therefore, that no apologies are needed for 

 the present work. Whatever its shortcomings and defects, he 

 claims at least the honor of making the first attempt to intro- 

 duce among American Colleges and American Engineers a 

 knowledge of a subject of approved interest and practical value 

 to both, whether regarded as a geometrical discipline or as a 

 most efficient aid in investigations of stability. Nor is he with- 

 out hope that the next ten years may find the method as uni- 

 versally accepted at home as now abroad. 



The same difficulties certainly have not here to be encoun- 

 tered. The subject as here presented requires only a knowl- 

 edge of the elements of geometry as universally taught, and 

 can thus be readily introduced into our schools as well as read 

 by those practical engineers for whose benefit the method 



