INDUSTRIAL LABOUR 431 



will be less than on a horizontal surface. There is also a hori- 

 zontal component, H, proportional to the inclination of the slope, 

 which acts in opposition to the propulsive force. 



Obviously a tall man has an advantage over a short man, since 

 the former can more easily raise the handles of the truck so as to 

 bring the centre of gravity of the ]oad over the axis of the wheels, 

 O. 



Imbert made no calculations of the work done in wheeling 

 the stone truck. He stated, however ; that, on a smooth level 

 surface, and with the centre of gravity of the load in the same 

 plane as the axis of the wheels, the effort needed for propulsion 

 was 3 or 4 kilogrammes. Taking an average effort of 3-5 kg the 

 muscular work done by the arms in 10 effective hours would be : 



3-5 X 3,000 X 10 = 105,000 kilogrammetres. 

 The total daily work would therefore be : 



131,250 + 105,000 = 236,250 kgm. 



Differences in the nature of the ground, over which the truck 

 is wheeled, cause variations in the friction between the wheels 

 and the soil, and may therefore considerably modify the above 

 values. It is interesting to note that when working under normal 

 conditions the rates of respiration and pulse are increased from 

 25% to 40% and from 17% to 20%, with various subjects. This 

 is similar to the results observed in the use of the file. 



There is not much general fatigue this being chiefly confined 

 to the muscles of the arms, where it persists for a relatively long 

 time. Little fatigue is experienced in the right leg owing to the 

 strength of its muscles. 



328, Use of the Wheelbarrow.- This has been investigated 

 by the same general methods, f 1 ) As this vehicle has only one 

 wheel, the efforts needed to support and balance it under load 

 are greater than in the case of a two-wheeled truck, or cart, such 

 as the " cabrouet." Imbert found that, if the load was centrally 

 placed on the barrow, the effort of support was 42% of the total 

 load, P. Taking a barrow weighing 29 kg., the effort of support 

 in wheeling it empty will be : 



= 12 kg., approximately. 



We can leadily calculate the value of the net load x, numeri- 

 cally equal to the effort of support, from the equation 



_ (29+"*) 42. 



"Too" 



whence x = 21 kilogrammes. 



(*) A. Imbert (Bulletin de I' Inspection du Travail, 1909, Nos. 1 and 2. 



