270 Rev. S. Haughton on the Muscular Mechanism 



3. Muscles extending the Metatarsus, or Cannon Bone, on the Leg. 



oz. 



16. Solseo-gastrocnemius 1 15*50 



1 7. Flexores digitorum (A) 16 -00 



18. „ „ (B) 975 



141-25 



The total combined effect of these muscles projecting the 

 body forwards is therefore approximately represented by 335-50 

 oz. of Ostrich-muscle*. 



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

 his spring through the air, the following muscles are employed 

 in flexing the several joints, so as to have them in readiness for 

 another spring as soon as the foot touches the ground. 



1. Muscles flexing the Thigh upon the Axis of the Body. 



1. Sartorius 18-00 



2. Iliacus 1*75 



The flexure of the leg upon the thigh seems to be effected by 

 the vis inertia of the former when the latter is drawn up towards 

 the body, in the spring. 



2. Muscles flexing the Cannon Bone upon the Leg. 



3. Tibialis anticus 8-75 



4. Extensor digitorum communis 5-25 



14-00 



* 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 physio- 

 logist. 



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 



R = 2Asin2e 



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

 found to be 1365 feet. This is the height to which 5| oz. are raised ; 

 and therefore the work done is found to be 4692 lbs. lifted through 1 foot. 

 Problem 2. A young man, weighing 120 lbs., leaps horizontally 20 feet; 

 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 1 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 acquired in running up 

 to the point of starting; and the whole art of long jumps resolves itself 

 into jumping vertically with a velocity equal to the acquired horizontal 

 velocity, and making both quantities a maximum. 



