An Act amending the act of May 18, 1937 (P. L. 654, No. 174), entitled, as amended, "An act to provide for the safety and to protect the health and morals of persons while employed; prescribing certain regulations and restrictions concerning places where persons are employed, and the equipment, apparatus, materials, devices and machinery used therein; prescribing certain powers and duties of the Department of Labor and Industry relative to the enforcement of this act; and fixing penalties," further providing for the operation of plant railroads.