MOVEMENT 



39 



Time in minutes 

 ' f 2' 3' »'. S ' 



E 



2 13 



10* 



And this immense surface would 

 only be broken by a single fine 

 line dividing it diagonally into 

 two parts. This inconvenience 

 would in itself serve to condemn 

 the method from a practical point 

 of view. It can be avoided, how- 

 ever, by dividing the tracing 

 into sections, each of which ex- 

 presses the movement during a 

 given time. Thus Fig. 27 shows 

 concentrated on a narrow strip 

 of paper the various phases of a 

 movement which otherwise would 

 have required a surface six times 

 as large. 



On this strip of paper the 

 scale representing distance is con- 

 tinuous, but that representing 

 time is broken. After each period 

 of five minutes the curve returns 

 to the first time-division, but 

 remains on the distance-division 

 at which it has actually arrived. 

 From this point a new section 

 of the curve recommences. The 

 sections A> B, C, etc., thus ex- 

 press the progress of the moving 

 body over a distance of 25 hecto- 

 metres, and during a period of 

 30 minutes, and the curve is 

 quite as intelligible as would be 

 a continuous one requiring a 

 large surface of paper.* 



* The section A shows that, during Fie. 27.— Successive sections of 

 the first five minutes, the moving body the curve of a movement. 



15» 



IV 



25 



