428 THE HUMAN MOTOR 



325. Spade Work. Before considering earlier experiments, 

 Tayloi's remarks on the subject should be considered. They 

 3 re to the following effect : " It might be thought, at first sight, 

 that a few hours consideration would suffice to discover the essen- 

 tial principles involved in the use of spade or shovel. However, 

 up till now, the writer has never come across any contractor who 

 had any idea that scientific management could be applied to 

 the use of the spade or shovel. 



" For any man using a shovel, there is a given load correspond- 

 ing to his maximum yield. ... By selecting two or three men 

 and paying them extra wages for doing reliable work and then 

 gradually varying the shovel load and having all the conditions 

 accompanying the work carefully observed for several weeks by 

 men used to experiments, it was found that a first-class man would 

 do his greatest day's work with a shovel load of about 10-250 kg. 



Thousands of measurements were made with a stop watch, 

 to find the speed at which a mm, provided with a suitable imple- 

 ment, could drive his spade or shovel into the earth and lift it 

 with a proper load. These observations were made on the re- 

 moval of earth from heaps, the heaps standing on ground of 

 irregular surface, on wooden planks, and on iron plates. The 

 time was also carefully determined for the swing of the shovel 

 in throwing the earth to various distances and heights." 



Coulomb made some experiments on the value of the work 

 done in digging. His subject shifted a total of 45 J cubic metres 

 per diem. He used a shovel weighing 1-7 kg. and the average 

 weight of each spadeful of earth was 6 kg. The total load, spade 

 and earth, was therefore 7-7 kg., which is a smaller load than that 

 recommended by Taylor. Taking the average weight of a cubic 

 metre of earth as 1898 kg., the number of spadefuls was : 



45-25 X 1898 

 6 



As the labourer lifted his spade to a height of 4 metres the work 

 done in lifting the earth was : 



JK.OK vx I CQQ 



^p - X 7-7 x -4 = 43,000 kilogrammetres. 



He drove the spade into the earth to a depth of -25 m. and 

 exerted a pressure of 15 kg. The work done in this operation 

 was therefore : 



45-25 X 1898 x 15 x . 25 = 53 600 kgm 



Coulomb's total was therefore about 100,000 kgm. per diem, 

 or, adding the empty return -motions, about 116,000 kgm. This 

 is a relatively small value. 





