OF IRON BEAMS. 471 



lowing experiments was just 4 feet 6 inches, or 

 equal to the distance between the supports, 

 and three inches were added to each end of the 

 beam, beyond the points A and B, to lay 

 upon the pfops; the parabolic bottom was 

 likewise a little strengthened at the ends, as 

 in the figure. 



XIV. EXPERIMENT. 



Distanoe between supports 4ft. Gins, and depth of beam 

 djins. as before. 



DIltaentioDt of MctioD ia Inohes. 



Area of top rib = 2.3 x .315 = .72 - 1. 

 Area of bottom rib =4.06 X .57=5.314 5-^H 



Thickness of vertical part = .33. 

 Area of Section = 4.628 inches. 



Breaking weight = 15024 lbs. = 134 cwt. 16 lbs. 

 It broke by tension very near to the middle. 



Hence strength per square inch of section 

 = S = 3246 lbs. 



XV. EXPERIMENT. 

 "In this experiment the breadth of the bottom 

 rib only was increased as before. 



