=Gas-service Rules.=--The rules for the regulation of gas service are in many States under the control of a board or commission whose duty it is to form codes prescribing the measurement and sale of all public utilities. The following form, General Order No. 20, State Public Utilities Commission of Illinois, gives an idea of the requirements in that State for the sale of coal gas. RULE 3. REQUEST TESTS.--Each utility furnishing metered service shall make a test of the accuracy of any meter, upon written request by a consumer: Provided, first, that the meter in question has not been tested by the utility or by the commission within 6 months previous to such request; and second, that the consumer will agree to accept the result of the test made by the utility as determining the basis for settling the difference claimed. No charge shall be made to the consumer for any such test. A report, giving the result of every such test, shall be made to the consumer. RULE 4. ADJUSTMENT OF BILLS FOR METER ERROR.--If on any test of a service meter, either by the utility or by the commission, such meter shall be found to have a percentage of error greater than that allowed in Rule 11 (see below) for gas meters, the following provisions for the adjustment of bills shall be observed. (_a_) _Fast Meters._--If the meter is faster than allowable, the utility shall refund to the consumer a percentage of the amount of his bills for the 6 months previous to the test or for the time the meter was installed, not exceeding 6 months, corresponding to the percentage of error of the meter. No part of a minimum, service or demand charge need be refunded. (_b_) _Slow Meters._--If the meter is found not to register or to run slow, the utility may render a bill to the consumer for the estimated consumption during the preceding 6 months, not covered by bills previously rendered, but such action shall be taken only in cases of substantial importance where the utility is not at fault for allowing the incorrect meter to be in service. RULE 11. GAS-METER ACCURACY.--(_a_) _Method of Testing._--All tests to determine the accuracy of registration of a gas service meter shall be made with a suitable meter prover. At least two test runs shall be made on each meter, the results of which shall agree with each other within one-half per cent. (1/2%). (_c_) _Allowable Error._--Whenever a meter is tested to determine the accuracy with which it has been registering in service, it may be considered as correct if found not more than two per cent. (2%) in error, and no adjustment of charges shall be entailed unless the error is greater than this amount.