172 



THE HUMAN MOTOR 



Take next a constant weight, say 1 -5, kg. and by increasing the 

 number of contractions, carry it to 4-48 metres, 8-84 metres, 

 13-26 metres and 17*68 metres in the same time. The speed will 

 therefore increase as 1, 2, 3, 4, also the work. The following 

 results were obtained : 



As might have been foreseen, there is increased expenditure, 

 but there is an economy in the total expenditure, as the same 

 amount of work is produced with a small load and a great speed, 

 instead of as before when there was a heavy load and a small speed. 

 This result is of geat practical utility, as it shows that a heavy 

 load should be divided and this division compensated for by a 

 suitable increase of speed. 



Example. A weight of 6 kilogrammes has to be transported 

 to a sixth floor, situated at a height of 17-60 metres. 



If carried up in a single journey cu. cm. cu. cm. 

 the expenditure would be ... 324 x 4 == 1,296 



If carried in fractions of 1-5 kg., 

 the expenditure would be 



In the second case there is an 

 economy of ......... 324 cu. cms. 



324 



representing - f about 25% of the total expenditure. At 



243 X 4 = 972 



the same time the waste entailed by the return journeys empty 

 handed must not be disregarded. 



117. From the above tables, giving the value of Dd for in- 

 creasing weights and speeds, the expenditure per kilogrammetre 

 can be found : 



cu. cm. cu. cm. en. cm. cu. cm. 



For increasing weight ... 14-90 11-90 lfe-10 12-20 

 speed ... 13-70 11-30 1JO-00 9-10 



The economy increases with the speed and reaches a maximum 

 value for a weight of 3 kilogrammes, which corresponds to an 



( l ) D, is taken from the preceding tables, p. 179). 



