Mass. Gen. Laws ch. 149 § 108
In every weaving and spinning department in a textile factory wherein water is introduced for humidifying purposes there shall be provided, maintained and kept in correct working order, for the purpose of recording and regulating the humidity of the atmosphere and the temperature, at least one set of standardized wet and dry bulb thermometers, and, if required by an inspector, two sets of such thermometers, and the following regulations shall be observed in their use: (a) The thermometers shall be placed as directed or sanctioned by an inspector, and be plainly visible to the workers. (b) The occupier or manager or person for the time being in charge of the weaving or spinning department shall read the thermometers thrice in the day, namely, between seven and eight o'clock in the forenoon, between ten and eleven o'clock in the forenoon and between three and four o'clock, except in rooms lighted by gas, and then between four and five o'clock, in the afternoon of every day when persons are employed in any weaving or spinning department, and he shall record the readings of each thermometer in such department at each of the said times upon a form provided therefor, which, together with the regulations relating thereto, shall be furnished by the department of labor and workforce development. The records of the readings shall not be destroyed until the inspector in whose district the factory is situated has examined them and given his consent to their destruction.
Mass. Gen. Laws ch. 149, § 108