DEFINITIONS AND MECHANICAL PRINCIPLES 



21 



this way is shown in Fig-. 10. Often the paper is ruled 

 to scale so that direct readings may be made from the 

 paper. Methods of rotating the reel or spool vary in 

 different makes. Some German dynamometers rotate the 



FIG. 10 A RECORD OF DRAFT OBTAINED BY A RECORDING DYNAMOMETER 



reel by a wheel which runs along on the ground and is 

 connected to the reel by a flexible shaft, as in Fig. n. 

 This method is very satisfactory, except that the wheel is 



FIG. II A GERMAN RECORDING DYNAMOMETER WHICH HAS THE REEL 

 DRIVEN BY A WHEEL TRAVELING ON GROUND 



often in the way. Distances along the paper are in this 

 case proportional to the distance passed over by the im- 

 plement. 



