APPENDIX.] NOTE TO CHAP. H. 36" 



of inertia of the forces ; while, finally, in a loaded beam the de- 

 flection curve itself is but a polygon or frame of this character, 

 when the curve of loading follows the law of the moments in 

 the beam. 



It is upon this polygon and its properties that the entire 

 system of Graphical Statics is based. 



