igos] MERRIMAN— DEPTH OF A BRIDGE TRUSS. 165 



30 



0.09 



which give laws similar to those of the economic depth, and which 

 show that the depth which gives the greatest stiffness is slightly 

 less than the economic depth. It hence appears that no additional 

 stiffness can be imparted to a bridge by giving to the truss a depth 

 greater than the economic depth. 

 April, 1905. 



