Mr. B. Bevan on the Adhesion of Nails. 169 



The percussive force required to drive the common six- 

 penny nail to the depth of one inch and half into dry Chris- 

 tiana deal, with a cast-iron weight of 6*275 lbs., was four blows 

 or strokes falling freely, the space of 12 inches; and the steady 

 pressure to produce the same effect, I found to be 400 lbs. 



A sixpenny nail, driven into dry elm to the depth of one 

 inch across the grain, required a pressure of 327 lbs. to ex- 

 tract; and the same nail, driven endways or longitudinally into 

 the same wood, required a force of 257 lbs. to extract. 



The same nail driven two inches endways, into dry Chris- 

 tiana deal, was drawn by a force of 257 lbs.; — to draw out one 

 inch, under like circumstances, took 87 lbs. only. The rela- 

 tive adhesion, therefore, in the same wood, when driven trans- 

 versely and longitudinally, is 100 to 78, or about 4 to 3 in 

 dry elm; and 100 to 46, or about 2 to 1, in deal. The rela- 

 tive adhesion under like circumstances to elm and deal is 

 found to be about 2 or 3 to 1. 



The progressive depths of a sixpenny nail into dry Chris- 

 tiana deal by simple pressure, were as follows : 



One quarter of an inch a pressure of . 24 lbs. 



Half an inch 76 



One inch 235 



One and half inch 400 



Two inches 610 



I may observe, that in the above experiments great care 

 was taken to apply the weights steadily, and that towards the 

 conclusion of each experiment the additions did not exceed 

 10 lbs. at one time, with a moderate interval between, gene- 

 rally about one minute, sometimes 10 or 20 minutes. In 

 other species of wood, the requisite force to extract the ncil 

 was different. Thus, to extract a common sixpenny nail from 

 a depth of one inch 



Out of dry oak, required 507 lbs. 



dry beech 667 



green sycamore 312 



A common screw of l-5th of an inch diameter, I have 

 found to have an adhesion about three times that of a six- 

 penny nail. 



From these experiments I am able to infer, that a common 

 sixpenny nail, driven two inches into dry oak, would require 

 a force of more than half a ton to extract by steady pressure ! 



I am, gentlemen, yours &c. &c. 



B. Bevan. 



Vol. 63. No. 311. March 1824. Y XXX. Papers 



