the Weight of < 'ontim nt* and Mountains. 259 



In Table VII, § 9,* are given the experimentally deter- 

 mined values of the breaking stress-difference for various 

 substances. The table is divided into two parts, in the former 

 of which the stress-difference was produced by tension, and in 

 the latter by crushing. It is not necessary here to advert to 

 nee in meaning of the numbers given in the first col- 

 umn and those given in the two latter columns in the first half 

 of the table. 



The cases of wood and cast brass are the only ones where a com- 

 parison is possible between the two breaking stress-differences, 

 as differently produced. It will be seen that the material is 

 weaker for crushing than for tension. For the reasons given in 

 that section, I am inclined to think that these tables rate the 

 strength of the materials somewhat too highly for the purposes 

 of this investigation. I conceive that the results derived from 



ashing are more appropriate for the present purpose tha 



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nately the re 



ally derived 





Produce,! by crushing 









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