230 



ANIMAL MECHANICS. 



num. The measurements for these two points are, 

 At pubes, 20 = 65°/= 3.12 x 0.17, 

 At sternum, 20 = 45°/= 7.16 x 0.17. 



Hence, we find the vertical strain producible at the sternum, 



by the internal oblique muscle, to be 



2 x 7.16 x 0.17 x versin 4c 0 



- - = 0.13c. 



5.41 « 



and the vertical strain, producible at the pubes, by the same 



muscle, 



2 x o 12 x 0.17 x versin 6c° 



2 L 2_ = o.I IQ. 



5.41 



Let us now add together the vertical strains at the point 

 in the linea alba, just above the pubes, and we shall find, 



Rectus abdominis, 0.290 



Obliquus eocternus, 0.614 



Obliquus interims, o i*3 



Transversalis, 0.000 



1.017 



We have seen that the vertical tension, producible by the 

 muscles acting at the navel, was represented by 0.630 only ; so* 

 that in order to calculate the maximum hydrostatical pressure, 

 producible inside the abdomen by the abdominal muscles 

 acting to the greatest advantage, we should increase the num- 

 bers given in the table, page 228, in the proportion of 1017 

 to 630. 



If we take the largest number in the table, corresponding 

 to No. 2, we have 



maximum pressure n 1017 . n 



inside abdomen = 22 ' 8 4 x ^ = 3<^7 lbs. per sq. in. 



This result agrees well with that given, from direct experi- 

 ment (p. 163), as the maximum expulsive force of the ab- 

 comina] muscles — viz, 38.47 lbs. 



