8 I.l\ I -I .\i> . 1:1 -M -, 



influence line equals the ordinate at the left minus the 

 ordinate at the right end of this segment divided by the 

 corresponding interval. The coefficient C at any salient 

 point equals the slope of the .segment at the left minus the 

 slope of the segment at the right of this point. The sub- 

 traction- in each case are made algebraically. 



It should be remembered, as has already been pointed 



out in Art. 2, that the value of any coefficient C may also 



be measured graphically from an influence line which has 



drawn to Male. F'r r\;imple, in Fig. 3 the value of 



thee.M'flieient (\ = - and T 4 = -. 



Xt Xi 



The algebraic calculation of the coefficients at all sa- 

 lient points of the influence line in Fig. 3 is given below. 

 If it be assumed that this influence line has been drawn 

 to scale, the signs of the numerical values of the slopes and 

 coefficients will be as given in the parentheses. 



C, 



*4 - } 



C 6 = s 4 - 



A numerical evaluation of the slopes and coefficients for 

 this influence line is given in Fig. 15 of Art. 8, which the 

 reader should check in order to understand completely the 

 : i iet hex! of procedure. These coefficient- should also be 



checked by the graphical method as already explained. 



> -<| 

 For example, in Fig. !."> the value of C s = - - = .0863. 



5U 



It will be noted in the algebraic calculation of the coeffi- 

 cients C at all salient point- that each slope enters once 



