376 



THE HUMAN MOTOR 



Walking with a Load. The expenditure of energy natur- 

 ally increases when the subject carries a load. At a speed of 4-5 

 km. per hour and with such a comparatively small load as 7-3 kg. 

 the writer found that the total increase was as much as 20%. 

 Expressed in metre-kilogrammes it varies with the magnitude 

 of the load and the speed of walking. 



The following table (from the results obtained by Kolmer and 

 Brezina) gives the expenditure of energy per metre-kilogramme 

 for loads from 11 to 53 kilogrammes and speeds from 3 to 6-6 

 kilometres per hour. 





The figures in italics show which are the most economical 

 speeds for the various loads. It will also be seen that the most 

 economical combination of speed and load is 21 kg. and 4-2 km. 

 per hour, for which combination a consumption of -454 small 

 calories is obtained which is the lowest figure in the above table. 



But the industrial problem is to find the maximum production 

 of daily labour. In other words, to discover the conditions as to 

 speed and load, by which, in any given time, the maximum out- 

 put of work can be obtained with a steady minimum of fatigue, 

 which latter is a measure of the energy expended. 



The financial aspect must not be overlooked, both because 

 a journey, under load, is generally followed by a return journey 

 unloaded, which unprofitable journeys should be reduced as far 

 as possible, and also because the worker has often no power to 

 modify his speed to suit his load. 



The following table exhibits the relations between metre- 

 kilogrammes per minute, for values from 4,000 to 12 000 and 

 ifferent loads, and will be found to lead to some interesting 

 results. 



