THE PRINCIPLES OF MYODYNAMICS. l5g 



the sum of the forces at the ends equal the force 

 in the continuity of the lever. 



142. In order to determine the resistance of 

 cancellous bone, I have cut off the ends of long 

 bones and subjected them to pressure. A few 

 points in regard to these experiments are suf- 

 ficient for our present purpose. The results are 

 only approximate. The bone ends, in one case, 

 will have more power of resistance than the 

 bone-ends in another case. I make the follow- 

 ing record in regard to the ends of a well-formed 

 and apparently healthy femur : — 



(i.) The head was cut off at its junction with 

 the femoral neck, making two -thirds of a spher- 

 oid, whose diameter was about one inch and a 

 half. It contained about 1.7 cubic inches of 

 cancellous bone. The cut surface of the head 

 was put on a resisting surface and pressure 

 gradually applied to the top of the head by 

 means of a steel lever. When the pressure was 

 about 400 pounds, the top of the femoral head 

 began to flatten, and continued to be depressed 

 as more and more force was applied till pressure 

 was about 2,200 pounds, when the femoral head 



