AT BROUGHTON. 397 



From these experiments it appears, that 

 stretching a wire frequently, even to its breaking 

 point, does not materially reduce its power of 

 bearing again. The case in a bolt may not 

 be exactly the same, as in a thin wire, the 

 manufacture of the two being different; but it 

 does not seem probable that any great difference 

 would arise from that cause. Hence the objec- 

 tions against high testing of chains formed of 

 straight bars, must be small when compared 

 with the dangers from defective welding. 



These remarks may not be irrelevant, for I 

 once saw in the main chain of a suspension 

 bridge, one of the links with a large crack in 

 it, stopped up with putty. 



