PROBLEMS OF MODERN SCIENCE 



in the length of the thigh-bone, and will tend to 

 compress the lower end. If the lattice-work which 

 goes to make up this end of the bone is sliced 

 through, it presents the appearance of such deli- 

 cate lacework as to suggest frailness. The minute 

 slender bars which constitute the lattice-work have, 

 however, a very definite arrangement. Most of 

 the bars are vertically set that is, exactly in the 

 direction in which the pressure of the body-weight 

 makes itself felt. Although any individual bar 

 could not by itself bear any considerable pressure 

 force, yet the total complement of the vertical bars 

 endows this end of the bone with a resistance 

 easily sufficient to withstand any compression to 

 which it is subject during life. The vertically 

 set, pressure-resisting bars are connected or tied 

 together by shorter cross-bars. These cross-bars 

 tying the vertical bars together prevent their 

 spreading or buckling, as they are liable to do 

 when being pressed upon from above, and are an 

 essential and important part of the anangement. 

 In short, the lattice-work occupying the lower 

 end of the thigh-bone is, in builder's parlance, a 

 complicated system of struts and ties. 



One of the most beautiful examples of lattice- 

 work, enabling a comparatively small, light bone to 

 withstand enormous stresses, is found in the heel- 

 bone. The bones of the human foot are disposed 

 in the form of an arch supporting the body and 

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