APPENDIX. 549 



direct tensile strength of the bolt, its relative 

 strength or the weight to break it across is 

 therefore i of that strength. Whence it appears 

 that the bolt was but J of the strength that it 

 ought to have been to have resisted the full 

 tension of the chain, with the eyes of its bars 

 rounded and only acting at their centers ; since 

 the diameters of the bars and the bolt were 

 the same. 



We here see an absurd consequence of the 

 theory of Galileo ; — for if the strength of the 

 bolt be estimated by that theory, the bolt 

 would appear to be just as strong as the other 

 parts of the chain; and therefore the failure of 

 the structure may perhaps have arisen from 

 the application of an erroneous theory. 



The accident was perhaps in some degree 

 hastened through the inferior quality of the 

 iron in the bolt, which had broke straight 

 across, presenting the granular aspect of cast 

 iron; without any fibrous appearance, which 

 is shown by good wrought iron. It appeared 

 too, from the form of the fracture, that the 

 surface of tension had been considerably larger 

 than that of compression, as would have been 

 the case, though not to be traced, in cast iron. 

 It is probable, however, that the bolt was not 



