862 Transactions of the American Institute. 



(2,240 pounds), but there were some used ranging from a thousand 

 to forty -five hundred pounds. 



The experimental piles were selected so as to show the effect of 

 the size of the pile, the weight and fall of the ram, and the rapidity 

 of the blows, as determined by the record before alluded to. 



The analysis of these experiments showed the following general 

 laws: 



1. That when the height of the fall of the ram was increased, 

 the sustaining power of the pile (driven home) was increased in 

 the ratio of the square root of the fall. 



2. That when the weight of the ram was increased, its effect was 

 to increase the sustaining power of the pile by 0.7 to 0.9 times the 

 amount of the ratio due to such increased weight. 



3. That when piles of the same size were driven by the same 

 hammer and from the same height of fall to different depths, their 

 sustaining power was in the ratio of the squares of their frictional 

 surfaces of penetration. 



4. That a pile driven home by a hammer of a ton weight, falling 

 thirty feet at the last blows, in such material, would sustain as many 

 tons as there were superficial feet of exterior surface of the pile 

 in contact with the earth, which, however, may be considered as 

 excluding the support due to its sectional area. 



The formula above stated is based upon these laws (excluding the 

 third), and the co-efficient is reliable for such material as was found 

 at that place. 



It is very desirable that similar experiments should be made in 

 soils of different kinds, which would make this formula applicable 

 to all the usual cases met with in constructions. 



I have made experiments elsewhere, but unfortunately they were 

 in soil too nearly similar to the above, to enable me to give any 

 new co-efficients. They served to show the general accuracy of the 

 formula given. 



I may here remark that the circumstances of each particular case 

 must determine how much of the absolute sustaining power should 

 be deducted to show the load which can be safely imposed upon the 

 piles. 



When there is no danger from the vibrations of the structure 

 being communicated to the piles, nor from the scouring action of 

 the water, they may be safely loaded with one-third of the weight 

 determined by the formula. 



The sustaining power of a pile driven home, the resistance which 



