4$^ THE STRENGTH 



from the same model, which varied only !W 

 the breadth of its vertical part, the depth of 

 the beam being all that was intended to vary. 

 The depths were nearly 4, 5, 6, and 7 inches ; 

 but aiccurate admeasurements are given with 

 the sections. 



The vertical part in the beams was rendered 

 too strong comparatively with the size of the 

 bottom rib ; it was desirable it should be so, 

 that they might all break by tension, or in 

 the same manner, to furnish the means of 

 judging correctly of their relative strength. 

 Tlie bottom rib ought otherwise to have been 

 made stronger, or the vertical part thinner. 



XXIII. EXPERIMENT. 



Distance between supports 7 feet, depth of 

 beam 4.1 inches. 



. )]|ime)isipiu of section at place of fracture, 

 or middle. 



Area of to^rn)=2.25x. ^3=74 ms. ^ i 

 „bottom „= 6.00x74 =4.44,, ' & 



Thickness of 1 .^ . , 



> = .40 inches, 

 vertical part 3 ^ / 



Area of section = 6.54^ I'S'l^Xi 



Weight of castihg = ItM, qrs. 2 lbs. = 11 4 lbs. 



