460 THE HUMAN MOTOR 



in climbing. This figure, however, seems to the writer to be 

 altogether excessive. 



By reducing the duration of the work the power exerted can be 

 increased. Thus a man lifted a weight of 12-24 kg. to a height 

 of 71465 metres in 145 seconds by means of a rope and pulley. 

 This gives as the power exerted 



12-24 X 71465 = 1 (1) 

 145 



A wood sawyer made to 200 working strokes of the saw in 145 

 seconds. The" length of each stroke was 487 metres and the 

 equivalent effort 12-24 kg. at the end of the time the workman 

 was in a somewhat breathless condition, and certainly could not 

 have continued to work at this rate for more than three minutes 

 without a rest. The power exerted in the working strokes was 



487 * 12-24x200^ 8 . 22 kgm . 

 145 



Adding the power exerted in the return strokes the total was 

 about 12-5 kgm. equivalent to H.P. 



A man weighing 65-1 kg. raisedihimself to a height of 20-15 

 metres in 34 seconds, and at the end of this time was quite out 

 of breath. The power developed, which can easily be estimated 

 amounted to 



S5-1X 20-15 m4M 



34 



Thi:s is slightly over J H.P., and is the highest value which has 

 been recorded. The period of time was, however, very short. 



M. Lefevre calculated the power exerted in a climb of two hours 

 up a mountain as -45 H.P. 



Many other calculations of the power of man could be given. 

 They would, however, only prove that the human motor has no 

 intrinsic potver, but that its power capacity is the resultant of 

 the numerous factors and variables which must occur in daily 

 work. The power which can be developed for very short periods 

 is a matter of but little practical importance. In the same way 

 the speed of a runner in a sprint race of 100 metres may reach a 

 rate of 33 kilometres per hour (the average of some of the best 

 short distance runners shows that the 100 metres is covered in 

 11 seconds, which is a speed of 32-73 km. per hour). Long dis- 

 tance races of 40 and 100 kilometres, such as the " Marathon " 

 race are tests of endurance. The best time on record for 40 km. 

 was 9,330 seconds, a speed of 16 km. per hour approximately. 

 (H. Siret at Paris, August 27th, 1911) ; 100 km. has been covered 

 (by Littlewood in 1884 and Jack in 1909) in nine hours, which 



(^ Amontons (Mem. Acad. Roy. Sciences, 1703. p. 100). 



