58 



horizontal axis, we find the following muscles to represent the moment 

 of the spring forwards : — 



I. — Muscles extending the Thigh on the A 



.xis of the Body. 



1 Tensor va° - in93 femoris ...... 



' • • ) 





. . . ! 46-75 









. . . 41-25 





. . . 17-00 



6 Semitendinosus 



14-00 





. . . 4-50 





... 4 75 





. . . 4-00 





132-25 



II. — Muscles extending the Leg on 



the Thigh. 









.... 25 25 



12. „ „ (2) 



. . . . 5-00 





. . . . 13-50 



14. 5 „ (2) 



.... 3-75 





. . . . 7 25 



62-00 



III. — Muscles extending the Metatarsus on the Leg, 



16. Gastrocnemido-solseus, 115-50 



17. Flexores digitorum (A\ ........... 16-00 



18. Flexores digitorum (B), 9 75 



141-25 



The total combined effect of these muscles projecting the body for- 

 wards is therefore approximately represented by 335*50 oz, of Ostrich 

 muscle.* 



After the foot of the Ostrich has left the ground, and during his 



* If we knew the weight of the Ostrich, and the length to which it can spring in a 

 single maximum stride, we could easily calculate the work done in a single effort by a 

 given weight of Ostrich muscle. I do not know how far an Ostrich in a state of nature 

 can spring, nor how high, and am therefore unable to make the required calculation ; 

 but I give here two corresponding problems for man, which may be interesting to the 

 physiologist. 



Problem 1. — A cricket ball, weighing 5| oz., is thrown a distance of 91 yards; find 

 the work done by the muscles. 



The thrower, by practice, finds the angle of maximum range, or 45° ; and as 

 It = 2h sin 2e 



for the maximum range, h the height due to the velocity of projection is found to be 

 136-5 ft. This is the height to which 5| oz. are raised, and therefore the work done is 

 found to be 46*92 lbs. lifted through one foot. 



Problem 2. — A young man, weighing 120 lbs., leaps horizontally 20 ft. ; what is the 

 work done ? By the same method of calculating, we find the work done in this case 

 to be 1200 lbs. lifted through one foot. This large amount of work is not given out in 

 a single spring ; for it represents the sum total of the single spring and of the velocity 



