76 THE ENGINES OF THE HUMAN BODY 



from the outer wall of the cylindrical shaft rises another 

 spray of fine plates or beams which, arching into the 

 neck, end by interlacing with the struts rising from the 

 inner side of the shaft. This second system serves as 

 ties for the first series, and thus strengthens the neck and 



Great Ties or 



trochanter. tension 

 \ lines. 



Struts of 

 support lines. 



Head. 



' 'Arched lines. 

 Small trochanter. 



Cylinder 

 or Shaft. 



FlG. 20. -An X-ray picture to show the design or construction of the upper 

 end of the thigh-bone. 



helps to transmit the weight falling on the head of the 

 bone to the outer wall of the shaft. In 1867 Professor 

 Culmann, a famous Swiss engineer and mathematician, 

 paid the bone-builders of the neck of the femur a great 

 compliment. The design they employed, he found, was 

 exactly similar to that applied in the Fairbairn crane — 



