Section 122. Violations of sections one hundred and seventeen to one hundred and twenty-one, inclusive, shall be punished for the first offence by a fine of not less than twenty-five nor more than one hundred dollars, and for a subsequent offence by the fine aforesaid or by imprisonment in jail for not more than two months, or both. A criminal prosecution for the violation of section one hundred and seventeen or one hundred and eighteen shall not be begun unless an employer has for four weeks after the receipt of a written order from an inspector neglected to comply therewith.