388 THE HUMAN MOTOR 



By the above system he removed 55,000 cubic metres of earth 

 with an economy of 75%. 



The following observations, hitherto unpublished, were made 

 by the writer in the years 1910 and 1911. 



1. A labourer weighing 85 kg.,. 45 years of age, carried 7 

 bundles of wood, each weighing 50 kg., to a height of 12-71 metres. 

 His speed was -17 metres, and he made 12 such trips per diem, 

 hence : 



_((50 + 85) 12-71 X 12 >: 7 = 144,131 kgm. (ascending). 

 T ~\ 85 X 12-71 x 7 X 12 X_52 = 47,189 kgm. (descending). 



100 

 Total 191,320 kgm. 



2. In a single afternoon another labourer carried to the 

 seventh floor of a building, a height of 22 metres, 36 sacks weigh- 

 ing 50 kg., each at a speed of -12 metres. Here : 



1 ^9 



T = (70 + 50) X 22 x 36 x = 144,461 kgm. 



100 



Adding to the above figure three such deliveries, made during 

 the same morning, equivalent to 42,126 kgm. and a walk of about 

 H kilometres, the total reached 200,000 kilogrammetres. 



298. The Inclined Plane. Little attention has been devoted 

 to this subject, although the various relations between height, 

 load, speed and inclination are of interest and importance in our 

 present investigation. 



Zuntz and Schumburg f 1 ) confined their investigations to in- 

 clinations varying from 0-6'-30" to 3-44' : 15", but their results 

 are vitiated by the fact that they consider walking up an inclined 

 plane as, in all respects, equivalent to walking the equivalent 

 horizontal distance, and then ascending to the height of the plane. 

 This, though true from the point of view of mechanics, is wrong 

 physiologically. Nor did they make any measurements of the 

 expenditure of energy in descending the planes. 



Such experiments are not easy satisfactorily to carry out. 

 Special apparatus is necessary for accurate results such as a gang- 

 way of considerable length, about 200 metres, of which the slope 

 can be adjusted. 



The writer constructed ( 2 ) a plane 12 metres long, of which the 

 slope could be varied from 8 to 13 centimetres per metre. He 

 used this apparatus to investigate the effect of steep gradients. 

 The subject walked at a steady pace from the ground on to the 

 plane. The consumption of oxygen was measured in ascent 

 and in descent. 



(*) Zuntz and Schumburg, Physiol. des Marsches, pp. 238, sqq., 1901. 

 ( 2 ) Jules Amar (Comptes Rendus Acad. Sc., 25 May, 1911, p. 1327). 



