OF IRON BEAMS. 4W 



llie wedge, and therefore at Jths of the depth 

 of the beam, since 3.9 inches = 1x5} inches 

 nearly. 



26084 



Hence, strength per square inch of section 



-^j. = 4076 lbs. which is much greater than 

 that in any of oiu: former experiments. 



Comparing this result with that of the common 

 beam in experiment 22nd, which was cast with 

 these, and which bore 2885 lbs. per inch, we 

 have 4075 - 2885 =1190 lbs. = excess. 



.". Gain in strength, from the section, = 

 ^ggg = .41, or upwards of 4 of what was borne 

 hy the common beam. 



The quantity of metal saved, through the 

 section, would be represented by the above 

 excess 1190, divided by 4075, the quantity 

 which the beam bore per square inch of section. 



•*• Saving of metal, from section, = ^^ = 

 .292, or -^ nearly. 



If we compare the strengths of this beam, 

 and that in experiment 22, by the weights, as 

 was done in experiments 11 and 12, we shall 

 have the saving in metal, through the section and 

 general form of the beam conjoined, = .377. 



