Polytechnic Association Proceedings. 893 



pile, thoroughly banded, is with a two-ton ram, to a depth of 

 about fifteen feet. 



At this depth the pile caused the hammer to rebound nearly a 

 foot at the last blow, and the destruction of the pile itself begins 

 to take place by shattering and brooming at the upper end. 



The first experiment to test the resistance to a withdrawing force, 

 was tried 17th May, 1851, when a lifting strain of 23,850 pounds 

 was applied to one pile for five minutes without moving the pile. 

 In this experiment a lever of the first order was emplo^^ed, one 

 foundation pile forming the fulcrum, and a large pile hammer 

 placed on the long arm of the lever producing the power as shown 

 in Fig. 1. 



The second experiment was made by applying a power of 20,000 

 pounds to another pile, with a lever of the second order, with a 

 steelyard to weigh the power at the long arm of the lever, as shown 

 in Fig. 2; and this method of applying the power was applied to 

 all other experiments. 



The third pile was then subjected to the same strain for five 

 minutes. 



The fourth pile was then tried, and resisted the same strain for 

 five minutes. There was then applied to this pile fourteen tons 

 for several minutes. 



Three other piles were subsequently tried, and each resisted ten 

 tons lifting strain applied for five minutes. 



On the 23d of May, the experiment of pulling a pile was com- 

 menced, beginning with ten tons (applied to No. 4, as before men- 

 tioned), and increasing the power one ton every two minutes, that 

 is, after ten tons had been applied for two minutes, eleven tons 

 were applied two minutes, and then twelve tons, and so on until 

 fifteen tons had been tried, when a hook of the steelyard broke. 

 After improving the apparatus for increasing the power, the experi- 

 ments were resumed, beginning with ten tons again and gradually 

 adding ton by ton, until there were thirty-one and a half tons 

 upwards or lifting strain applied to the pile. This experiment 

 lasted one hundred minutes; during the whole of this period the 

 lifting force was constantly applied. There was afterwards a 

 gradual increase of the lifting force to thirty-nine tons, without 

 moving the pile; it then resisted forty tons for half a minute, when 

 it began to rise very slowly. Forty-one tons were then applied 

 for one hundred seconds; then forty-one and a half tons for thirty 



