LOCOMOTION 379 



The speed of walking should not, under any circumstances, 

 exceed 5 km. per hour when carrying heavy loads. As the writer 

 remarks on p. 73 of his above-quoted work : "A man weighing 71 

 kg. carries a sack on his shoulders weighing 60 kg. and walks a 

 total daily distance of 22-311 km. at a speed of 4-82 kilometres 

 per hour. If he increases the speed of walking to 5-4 km. per 

 hour he will not be able to traverse more than 12-14 km. per day, 

 which is little more than half of the former figure. The maxi- 

 mum result was obtained when the load was 45 kg. and the speed 

 of walking 4-8 kilometres per hour. The experiments were 

 carried out for a period of from eight to ten days with each 

 subject, without fatigue, or any serious complaints. 



The maximum of daily activity is represented by 



(71 + 45) 25930 = 3,007,880 metre-kilogrammes. 

 This is undoubtedly the maximum result which can be obtained. 



291. Coulomb's Observations and Methods. Coulomb (*) was 

 the first to investigate the maximum work done in carrying loads. 

 He noted that, if the normal speed of walking was maintained an 

 increase of load caused a reduction in work, and in the daily out- 

 put. He took a subject weighing 70 kg. who carried a load of 

 62-3 kg. for a total distance of 17-32 kilometres and obtained, as 

 a result : 



17320 (70 + 62-3) 2,291, 436 metre-kilogrammes. 



It is hardly necessary to point out that the illustrious physicist 

 was in error in this calculation. It is by physiological considera- 

 tions alone that we can decide with certainty as to the load which 

 causes excessive muscular fatigue. Furthermore, the principles 

 of the science of energy were then unknown, nor had any con- 

 sideration been given to the waste of energy caused by " static " 

 efforts, or useless movements. Nor was it until M. Chauveau 

 and others of his school, carried out their investigations, that 

 the relations, between speed and load, conducive to the best results 

 were understood. 



It was by these principles that the able American engineer, 

 Frederick Taylor, was guided in his experiments as described in 

 the following paragraph. 



292. Handling of Pig Iron. In this elementary form of labour 

 the labourer had to stoop to pick up from the ground a billet of 

 iron weighing 42 kilogrammes, to carry it a few steps, and then 

 to put it down. 80,000 tons of pig iron were piled alongside a 

 railway siding. The labourers took the pigs, one by one from the 

 pile, walked up inclined gangways, and placed them in the rail- 

 way trucks. 



(*) Coulomb, loc. cit. (vide 122). 



