154: CONTINUOUS GIRDER. [CIIAP. X, 



the simple moment area) for the different positions of the load. 

 The distances cut off on the vertical through C by these lines 

 give, then, the various values of h or 2 2)J. If we draw from 



these intersections lines to the pole N, at the distance - I from 



o 



D C, the cross-lines are parallel to these lines. It will be best 

 to keep for each pair the common line P Q parallel to N C. 

 When the point of application of the load divides the span into 

 two equal parts, the poinfof intersection of the cross-lines di- 

 vides the middle third of P Q into equal parts. 



The centre of gravity of the simple moment area cannot pass 

 beyond the middle third of the span. Since any load can be 

 considered as made up of a number of concentrated loads, it 

 follows generally that /or any method of loading the centre of 

 gravity of the simple moment area lies between the third verti- 

 cals. 



