GAS AS A FUEL 151 



The reading of the index in the illustration is as follows: 



Reading of 1 thousand dial 200 cubic feet 



Reading of 10 thousand dial 4000 



Reading of 100 thousand dial. ....... 80000 



Complete reading of the meter . . 84200 



The amount of gas consumed for one month is obtained by sub- 

 tracting the reading of the meter for the last month from the reading 

 of the meter for the present month. 



Prepayment Meters. These meters are so constructed that one 

 can insert a coin and receive a certain amount of gas. After this 

 is used the meter will automatically cut off the supply of gas until 

 another coin is inserted. Most prepayment meters are so constructed 

 that when the gas paid for is nearly used, the supply of gas will be 

 gradually shut off, thus giving the consumer a chance to insert 

 another coin before his supply of gas fails entirely! The sudden 

 shutting off of the gas supply would be not only inconvenient but 

 dangerous, for if one should forget to turn off his burner the inser- 

 tion of another coin into the meter would allow gas to escape into 

 the home. Even when the meter does shut off the supply of gas 

 gradually, lights go out and -many accidents result. There is con- 

 siderable danger in the use of prepayment gas meters. 



One may easily check up the amount of gas received for the coin 

 inserted, by reading the meter at the time the coin is inserted and 

 rereading the meter when another coin is inserted. 



Cost of Gas Consumed per Hour in Appliances. One may easily 

 determine the cost per hour of any gas-consuming appliance. 



Shut off all gas appliances which consume gas through the meter. 

 Turn on the gas for the appliance whose consumption of gas you 

 wish to measure. Record the number of times the test dial revolves 

 per minute. It is usually better to make several tests for several 

 minutes and take the average. 



Multiply the number of cubic feet or parts of a cubic foot by 60. 

 Why? 



Determine the cost of gas per 1000 cubic feet from your gas 



