GENERAL CONSIDERATIONS. 157 



be more languid than in the parent trunks, as this circulation is 

 retarded both by additional friction and by -having to fill up a 



Square of Left Iliac, as above, - - . - . . . . lg(K) 



Ditto Internal Iliac - - - - - - - 961 



Ditto External do. - - - - . - - 900 



1861 



Branches largest by above 16 per cent., or 261 



Great Sinus of Valsalva - - - 13456 



Innominata - 2601 



Carotid 1444 



Subclavian - - - - - - - 1024 



Aorta beyond 3600 



8669 



Sinus greater than all, by- 4787 



or 55 per cent. 



Comparison o-fthe areas of the Iliac Arteries, with that of the Aorta, half an 

 inch above them, in decimals of an inch. 



Left Iliac. Aorla. Right Iliac. 



Greatest diameters - - .354 .556 .390 



Least do. - - - .290 .410 , .290 



Sum of diameters - - .644 .966 * .680 



Mean diameters ... .322 .483 .340 



Their squares - - - 103684 233289 115600 



103684 



Sum of the squares of the Iliacs ...... 219284 



Square of the Aorta 233289 



Aorta larger than the Iliacs - ' 14005 



or nearly 6 y 4 _ per cent. 



As the areas of circles are to each other as the squares of their diameters, it 

 follows that the aorta will contain, in a given length, nearly 6_1- per cent., more 

 than the two iliacs; and, consequently, the blood must flow that much faster 

 through the iliacs than through the aorta, as the same blood has to be disposed 

 of in both in the same time. By this means the power of the heart is continued 

 much farther through the system, as each artery is large enough to supply its 

 branches with but little friction. The interior surfaces of the above iliacs are, 

 together, 2.0806 inches, while that of the aorta is but 1.518 inches, or only three- 



VOL. II. 15 



