418 ELECTRICAL MACHINERY 



Scale of a Meter. The scale of an ammeter should be 

 uniformly graduated, but sometimes it is advisable to have 

 a voltmeter with a condensed scale on its lower ranges for 

 the purpose of getting a more open scale in the range where 

 it is always used. For instance a meter to be used on a 



FIG. 274. Diagram to Illustrate How Far a Well-damped Meter 

 "Overshoots" its Proper Reading. Weston Electrical Instru- 

 ment Co. 



600-volt circuit would probably have a total range of 700 

 volts; from zero to 400 volts the scale might well be con- 

 densed as the meter is practically never used on these ranges. 

 From 400 volts to 700 volts the scale could then be more 

 open than if the scale was uniform throughout its range. 

 The necessity for a clearly marked scale and large, easily- 



