vi CONTENTS 



The several bones of the skull; how begun; assumes the form 

 of an arch 17 



The cheekbones arranged like the flying buttress of Gothic 

 architecture; when a man falls, these buttresses protect 

 him and prevent what is known as thrusts ; see figures . 19, 20 



Fig. 5, section of St. Paul's, engraved by Hooker . . . . 19 



The joining of the bones is secured in another way; one 

 bone is divided at its edge to receive the next between its 

 two divisions 22 



Interior of the skull shows groins like joints of two meeting 

 arches. The base of the skull is strengthened .... 23 



CHAPTER II 



MECHANISM OF THE SPINE 



The column which sustains the brain-case difference in 

 pliancy and joinings; elastic material between joints; no 



two bones touch protects nervous system 25 



Bones of spine 26 



Curve of spine why so curved 27 



Comparison of mast of ship to spine 28 



Fig. 6, connection of spine with pelvis inclined; like a ship's 

 mast bends backward 31, 32 



CHAPTER III 



OF THE CHEST 



Union of the breastbone and ribs, the joinings, by means of 

 cartilage, -- save from injury; movements of the chest in 

 breathing, inspiration and expiration 36 



CHAPTER IV 



DESIGN SHOWN IN THE STRUCTURE OF THE BONES AND JOINTS 



OF THE EXTREMITIES 



Most perfect shape combining strength and lightness com- 

 pare a reed or quill and a bone; observe least possible 

 expense of materials 38 



