TJFiE STRENGTH 



FORM OF BEAM ALTERED. 



42. The beams in our future experiments were 

 of equal height, through their whole length, and 

 had their top and bottom ribs uniform in 

 thickness, but tapering toward the ends, the 

 bottom rib being parabolic. They are repre- 

 sented by the vertical plan and elevation 

 below, where the sections of their middle are 

 as in the following experiments; and the 

 sections, from their middle toward the ends, 

 as in experiments 11, 9, 3. 



PLAN. 



ELEVATION. 



■ 



This form was adopted to save metal, by 

 reducing the bottom rib, which was likely to 

 become very large. The reasonings by which 

 I was led to suggest these deviations, from 

 the form of the elliptical beam before used, 

 were the following. 



The vertical part, which was uniform through 

 the whole length,* being thin comparatively 



• The vertical part of the beam ou«jht like the ribs to have 

 been reduced toward the euds, considering the leverage only; 



