PROBLEMS OF MODERN SCIENCE 



follows that if the material of the stick were taken 

 away from the more deeply situated central part 

 and heaped on or towards the surface a greater 

 difficulty would be experienced or, in other 

 words, a greater force would be required in 

 breaking it. In short, the stick would be more 

 resistant to a breaking force. 



The result of taking away substance from the 

 central part of the stick and heaping it on the 

 surface would be to fashion a tube or hollow 

 cylinder, and hence the commonplace that with 

 a given amount of material a hollow cylinder is a 

 much more efficient construction for resisting a 

 breaking force than a solid column. 



The middle part of the thigh-bone is the part 

 of the bone where the breaking forces to which it 

 is subject are most effective, and here the walls of 

 the central or marrow cavity are thickest. Towards 

 either end of the bone breaking forces are less 

 effective, and thus is explained the gradual tapering 

 of the walls as they are traced to the two ends of 

 the bone. In the building of the shaft of the thigh- 

 bone the bony substance is obviously used with the 

 greatest economy, but at no sacrifice of efficiency. 



The principle of the hollow cylinder as a 

 mechanical contrivance exhibiting the maximum 

 amount of resistance with the expenditure of a 

 minimal amount of material occurs most extensively 

 in nature, being exemplified by the bamboo cane, 

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