OF IRON BEAM9. 505 



experiments 31, 32, and 33, these having been 

 made with the samie view, and only differing 

 from the beams in the preceding ones, by having 

 a larger bottom rib. 



60. All the beams (except those of the com- 

 mon form) were made like those described after 

 experiment 13; with this difference however, the 

 parabola of the bottom rib was, in the 4ft. 6ins. 

 beams, 3 inches longer than the distance between 

 the supports, viz. 4 feet 9 inches, and in the 9 feet 

 beams, 6 inches longer, or 9 feet 6 inches, this 

 was done to render the ends of the beams a 

 little stronger, agreeably to the remarks made 

 prior to experiment 23. 



XXVIII. EXPERIMENT. 



Distance between supports, 4 feet 6 inches. 



Depth of beam, 5f inches. 



Weight of beam, 81 lbs. 



Dimensions of tection in Inches. ^^^BCT 



Area of top rib 2.15x .27=.58 I 



„ bottom ,,6.74 >01=4.786 ^ B^ 



Thickness at A • gg--— — -. , » 



.53 ^^^^^A^^^^ 



Area of section 7.20 inches. 

 3 s 



