180 BENQUIRY INTO THE STRENGTH AND 
the granulated state of the bar, in order to re- 
sist the forces thus operating to produce rup- 
ture, either by compression above, or forcible 
extention below. 
From this view of the case, a question arose 
as to the actual state of the atoms under diffe- 
rent degrees of pressure ; it appeared to me that 
the tensible and compressed forces would at 
every change produce a new adjustment of the 
parts, and either afford evidence of their adap- 
tation to the load, or demonstrate a progressive 
yielding to a force sufficient ultimately to des- 
troy the resistance. 
On consulting the works of different authors, 
I found them nearly agreed in supposing that 
materials could be loaded to one-third or more 
of the breaking weight, without injuring their 
elasticity. In pursuing these experiments I was 
however led to a different conclusion, by obser- 
ved discrepancies in the bars, accompanied by 
much earlier indications of impaired elasticity. 
I mentioned this circumstance to Mr. Hodgkin- 
son, and found similar results had been obtained 
by him, in experiments made for the British 
Association previous to those now in progress. 
