34 W. & L. E, GURLEY f TROY, NEW YORK 



16. When the meter is not in use, disconnect the meter line 

 from the battery, so that it will not become exhausted. 



17. Do not strike the telephone receiver, as a heavy jar 

 will to a greater or less extent, demagnetize the pole pieces, and 

 to that extent will injure the receiver. If care is taken, it is 

 very improbable that the telephone receiver will get out of 

 order. 



18. Care must be taken not to short-circuit the dry battery 

 when the meter is not in use. To avoid this, the poles may be 

 wound with insulating tape. 



RATING THE CURRENT METER 



The relation between the revolutions of the meter cups and 

 the velocity of the water may be determined by rating each 

 meter before it is used. Theoretically, the rating for all meters 

 of the same make should be the same, but, as a result of slight 

 variations in construction, and in the bearing of the wheel on 

 the axis at different velocities, the ratings differ slightly. 



A meter is rated by moving it through still water with 

 uniform speed, and noting the time, the number of revolutions, 



I 

 FIG. 12. Current Meter Rating Station nt U. 8. Bureau of Standards. 



