ANIMAL MECHANICS. 



153 



membranes are pushed through the mouth of the womb — 

 bulging out into the segment of a sphere, and are in most 



!A 



cases ruptured by the pressure of the liquor amnii contained 

 in them. 



It is evident from the form of the gravid uterus, shown in 

 Fig. 21, that its curvature is greatest near its mouth, and equa- 

 tion (20) shows that for a given hydrostatical pressure, the 

 tensile strain is proportional to the radius of curvature ; hence 

 this strain will be greatest at the fundus of the uterus. If we 

 assume the shape of the uterus to be that of a prolate ellip- 

 soid, whose longer diameter is 12 inches, and shorter diame- 

 ter 8 inches ; its mean curvature will be that of a sphere whose 

 diameter is 9.158 inches. 



The volume of the gravid uterus is found from the expres- 

 sion — 



Volume = - 7r ab 2 : (21) 

 3 



in which a and b are the semiaxes, and it is the ratio of the 



