LOCOMOTION 383 



Some examples taken from infantry prove that the French 

 soldier can do, normally, 30 kilometres with an average load of 

 30 kilogrammes, that is : 



(70 + 30) 30,000 = 3,000 ; 000 metre kilogrammes. 



In certain special cases this result is exceeded. The speed is 

 usually about 5,500 metres. According to the military writer, 

 Vegece, the Roman soldier could cover 36 kilometres with a load 

 of 29 kilogrammes. 



294. Marking Time, f 1 ) In infantry drill " marking time " 

 appears to be often considered as if it was almost equivalent to 

 resting, whereas, in actual fact, it is only the motion of progres- 

 sion that is suspended, the muscular oscillations of the body 

 having practically the same value as in marching. 



In the following evaluation of the consumption of energy in 

 " marking time," it is assumed that the lateral oscillations of 

 the body are nil and that the legs alone move. 



Let n be the cadence of the motion, the number of flexions 

 and extensions per minute. In the following experiments (vide 

 fig. 271) the " respiratory valve " is carried on a fixed support, 

 the subject stands on a thick plank, to which his heels are 

 attached by two straps which limit the lift of the feet to a definite 

 amount. The following table gives the result of one experiment, 

 among many, the subject being an adult weighing 65 kg. 



The consumptions of oxygen in cubic centimetres per step for 

 various cadences were as follows : 



Consumption ... 2-25 2-521 2-708 2-911 3-115 

 Cadence ... ... 76 85 94 103 113 



The expenditure is : d = an -\- b 



a and b being constants having the following values : a -02 

 cubic centimetres and b = -83 cubic centimetres. 



The equivalent calorific expenditure, for the above cadences 

 can be calculated, and is -16, -178, -191, -206, -220 small calories 

 respectively, per step, per kilogramme. 



Thus " marking time " consumes about half the energy of 

 ordinary walking, and increases with the speed and the height to 

 which the legs are lifted. In the above experiment this height 

 was -13 metres. 



t 1 ) Jules Amar (Journal de Physiol. 1911, p. 314). 



