A SUGGESTED METHOD OF TEST 147 



ing it the flow can be increased or decreased as desired. It 

 should be all of metal free from leather or rubber packing, so that 

 when once placed the flow of water through it will not change 

 until the control is moved. 



The water should then go to a standard orifice placed in an 

 enlargement of the pipe. A mercury manometer, connected 

 with the water on either side of the orifice, would show the pres- 

 sure upon it. Several orifices of different diameters would be 

 required to measure the range in quantities to be handled, 

 the diameter of each orifice being perhaps 50 per cent greater 

 than the next smaller one. The rating of the orifices would 

 be done in the course of regular work and would not need to be 

 provided for in advance. A rapid method of shifting the ori- 

 fices is desirable. It may be that a series of them could be cut 

 in a disc which would be revolved on packing without appre- 

 ciable leakage, and so that the orifice could be almost instantly 

 changed by revolving the disc. 



The water would then go through the meter to be tested, or, 

 if desired, through a series of them. 



After passing the meters, the water would be discharged into 

 the air, or could be carried, if desired, to a weighing tank to be 

 used for checking up the higher rates of flow. 



The ordinary basis of measurement would be to collect the 

 water passing the meter in a glass graduate. Those used for 

 laboratory use, having capacities of 100, 200, 500 and 1000 

 cubic centimeters, are suitable. The water would be caught 

 for one minute, or for some other short interval of time, long 

 enough to allow the time to be accurately ascertained with a 

 stop-watch. The volume that passed in the interval would be 

 read directly in the graduate. The flow in cubic centimeters 

 per minute is then ascertained. The slide rule would naturally 

 be used for all calculations. One U. S. gallon contains 3785 cubic 

 centimeters and i gallon per twenty-four hours is equal to 2.63 

 cubic centimeters per minte. Dividing the number of cubic 

 centimeters per minute by 2.63, therefore, gives the rate of 

 flow in gallons per twenty-four hours. 



With any given orifice the rate of discharge will increase 



