ANATOMY 



of the bone where the cord of the calf-muscles is 

 fastened, and are accurately disposed in the lines 

 of strain to which the bone is subject when pulled 

 upon by these muscles. 



The second set of bars in the lattice-work of 

 the heel-bone obviously play a twofold part. 

 They tie the first set of bars, or pressure-bars, 

 together, enabling them more efficiently to resist 

 the compression due to the body-weight, and at 

 the same time they enable the bone to resist the 

 enormous strain put upon it by the powerful pull 

 of the calf-muscles. 



In spite of the great stresses to which it is 

 subject, the heel-bone never exhibits the slightest 

 indication of undergoing distortion, either in the 

 direction of being crushed or being pulled apart. 

 A dried heel-bone, the relic of a once heavy and 

 powerful man, was weighed, and was found to 

 consist of scarcely three-quarters of an ounce of 

 bony substance. It is almost inconceivable that 

 with such an inconsiderable amount of material 

 a bone of the size and of the resisting qualities of 

 the heel-bone could be built. 



Lattice-work as a structural device for resisting 

 stress is a human discovery later than that of the 

 hollow cylinder, and is rapidly coming more ex- 

 tensively into vogue. The graceful lattice-work 

 supports of the enormous cranes now at work on 

 the Aldwych site win the wonder and admiration 



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