Mass. Gen. Laws ch. 164, § 108: Calorimeter provided by company

Section 108. Every gas company or municipal lighting plant which distributes and sells to its consumers over fifteen million cubic feet of gas in a year shall, when required by the department, provide and maintain a suitable room not less than a quarter of a mile from the gas works with a calorimeter of a type and construction approved by the department, which shall be open at all reasonable times to duly authorized employees of the department.