LAWS OF BONE ARCHITECTURE 285 



analysis of a suitable deformed bone, together with the clinical 

 history of the case. The establishment of Wolff's doctrines upon 

 a sound mathematical foundation should lead to a wider recog- 

 nition of their importance and value both from the standpoint 

 of the correction as well as of the prevention of deformity. 



Homogeneity of spongy and compact hone 



Gebhardt ('01) has advanced a number of ingenious arguments 

 tending to prove that the spongy bone is not homogeneous with 

 compact bone as a structural material and that they do not act 

 together as a homogeneous structure. The close inter-relations 

 between the spongy and the compact bone in the upper and lower 

 femur, described in detail in Part IV, and the significance of 

 their morphology described in Part V, proves that compact and 

 spongy bone act together as a homogeneous structure. The 

 analysis in Part III makes clear that unless the spongy bone 

 possesses relatively the same strength as compact bone (weight 

 for weight) these two types of structural material could not act 

 together to form a homogeneous structure. 



Summary 



The general principles of applied mechanics and graphic stat- 

 ics are presented in brief form in Part II, and their practical 

 application to the analysis of the structure of bone, and es- 

 pecially of the femur, is indicated and illustrated by specific 

 examples. 



The detailed mathematical analysis is made of the mechanics 

 of the femur of a man in normal health who was accidentally 

 killed and whose weight was 200 pounds. The structural prop- 

 erties of the femur sections are analyzed by graphic methods 

 and the results shown in tables as well as by diagrams. The 

 effect of an assumed load of 100 pounds acting on the femur- 

 head in the same direction as the weight of the body, under 

 normal conditions, is analyzed at intervals of \ inch in the ex- 

 tremities of the femur and at 1-inch intervals in the shaft. The 

 amounts of the various stresses are computed for the assumed 



