CITY WATER SYSTEMS 497 



accurately. If in error it is generally owing to wear. In that 

 case the meter will likely register too small an amount of 

 water because some slips past the disk without causing it to 

 rotate. Water users sometimes complain of the meter's read- 

 ing too high. If a meter reads correctly when first installed, 

 it is almost certain later to read too low on account of wear. 

 Excessively high reading is generally on account of some undis- 

 covered leak in the piping or too lavish use of water. Leakage 

 is easily discovered, however, by means of the TEST-DIAL, a 

 pointer which indicates the consumption of a cubic foot and 

 fractions of a cubic foot (Fig. 305) . To test for leakage, close 

 all taps in the building and watch the test pointer for a few 

 minutes. If any serious leakage is taking place, the test 

 pointer will be seen to keep moving. 



584. How Water is Sold to the Consumer. Although water 

 is generally sold by the 1000 gal., meters often record the 

 amount used in cubic feet. There are 231 cu. in. in 1 gal., 

 while there are 1728 cu. in. in 1 cu. ft. There are, then, nearly 

 7.5 gal. in a cubic foot. 



PROBLEM 



If water costs 25 cts. for 1000 gal. and the daily consumption 

 for a city school building is 350 cu. ft., what is the cost of water per 

 day? Ans. 65+ cts. 



585. Reading the Water Meter. A water meter may have 

 either a STRAIGHT-READING REGISTER or a DIAL-READING REGIS- 

 TER. The straight-reading register needs no explanation (Fig. 

 305). The dial-reading register is so constructed that it re- 

 quires a complete revolution of the pointer on any circle to 

 indicate the whole number of cubic feet indicated above or 

 below that circle. The circumference of each circle is divided 

 into tenths. In the illustration (Fig. 306) the highest reading 

 pointer stands between 9 and 0. The circle is labeled 

 1,000,000 cu. ft. The pointer, therefore, indicates a reading 

 of something more than 900,000 cu. ft. The next pointer 



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