INDUSTRIAL LABOUR 



411 



Fig. 282. Experiment with journeyman fitter. 



The net dynamic expenditure is therefore : 



218-62 85-91 = 132-71 Calories. 



313. We have next to consider the muscular activity. The top 

 curve in fig. 280 represents the downward pressure of both hands. 

 The average for 158 strokes of the file was 10 kg. Hence : 



V + V = 10 kg. 



To this has to be added the weight of the file (1-85 kg.). Hence 

 the actual total pressure on the work is 11-85 kg. The horizontal 

 component of the right hand, H. was 2-2 kg. 



The efforts of the left hand were : 



Horizontal component 2-5 kg. 



Vertical component 6-8 kg. 



Hence 



V = 10 6-8 = 3-2 kg. 



As above stated, the actual length of file utilized was 26 cm., 

 this being fixed by two stop blocks (vide fig. 184). The effort of 

 the working stroke, 



H + H' = 2-2 + 2-5 = 4-7 kg. 



