INDUSTRIAL LABOUR 4\7 



of the surface of the work, may result in different "co-efficients of 

 utility " for the same total effort. Thus in Nos. 2 and 16'of the 

 table the total muscular effort was approximately the same, but 

 the useful efforts were 4-4 kg. and 5-6 kg. and the "co-efficients 

 of utility " 35-5% and 43-7% respectively. Such variations are 

 not, however, generally due to this cause, but result from increase 

 in the total effort and the number of strokes per minute. 



Measurement of the consumption of oxygen is the most accurate 

 method by which the influence of other variables, such as the 

 length and number of rest periods, position of feet, attitudes of 

 the body, etc., can be discovered. 



(c) Relations between the Expenditure of Energy and the Rate 

 of Filing. Columns 10 and 1 1 of the table give the expenditure 

 in great calories per kilogrammetre, and per gramme of filings 

 removed respectively. It will be observed that these are a mini- 

 mum for a rate of 70 strokes per minute when they are -025 Cal. 

 and 2-7 Cal. respectively. At this rate the weight of filings 

 removed per hour (Column 8) is about 82 grammes, and the hourly 

 output of work (Column 7) 8,800 kgm. The muscular efforts of 

 the right and left arms (Columns 3 and 4) are 7 kg. and 9 kg. 

 respectively, the total useful effort per stroke (forward and return) 

 is 8 kg. approximately, while the "co-efficient of utility" is 50% 

 (vide experiments Nos. 27, 32 and 33). 



(d) Influence of the Attitude of the Workman, In the experi- 

 ments Nos. 1 to 39, considered above, the workman leaned over 

 the vice somewhat, the upper part of his body being inclined at 

 an angle of about 20 from the vertical. In experiments Nos. 40 

 and 41 the body was maintained in an upright, though easy, 

 position, no change being made in the position of the feet. This 

 resulted in a reduction of about 4% in the hourly expenditure 

 of energy (Column 9) and 3J% in the useful effort (Column 5) 

 while the "co-efficient of utility " increased some 2J%. The out- 

 put remained practically unaltered, hence the economy was some- 

 what increased. It may also be remarked that an easy upright 

 attitude conduces to increased regularity in working. 



The periodic oscillation of the body is another cause of fatigue, 

 though this is but slight in the case of a skilled workman such 

 as the subject " A.C." With other subjects the body is thrown 

 forward during the working stroke and brought back with the 

 return stroke. At high rates of filing a considerable amount of 

 unproductive energy is thus expended. This unnecessary motion 

 is conditioned by the positions of the feet, the distance of the 

 workman from the vice, and the height of the latter in relation 

 to that of the workman. 



The following experiment was made in regard to the distance 

 of the man from the vice (vide fig. 287). 



