(1) Provide and install gages in each tunnel, for showing the air pressure to which the persons so employed therein are subjected. Such gages shall be accessible at all times during working-hours to all employes in the tunnels.

(2) Provide and attach gages to each caisson, for showing the air pressure to which the persons so employed therein are subjected, and employ a competent person, who may be the lock-tender, to take charge of such gages and of the instruments required under subdivision three of this section. The person so employed shall not be permitted to work more than eight hours in any twenty-four hours.

(3) Provide and attach an air-gage and a timepiece to each air-lock. Such gage and timepiece shall be accessible to the lock-tender at all times.

(4) Keep at least two air-pipes or -lines connected with each tunnel, caisson, compartment, or place in which persons are so employed.

(5) Provide a suitable iron ladder for the entire length of every shaft used in connection with such work.

(6) Keep every passageway used in connection with such work clear and properly lighted.

(7) Provide sufficient electric lights for all lighting purposes, and provide a wire for lighting the shaft, which wire shall be separated from the wire used for lighting the place where the employes are at work in compressed air; all electric wires shall be properly insulated.

(8) Provide, for the use of all persons so employed, dressing-rooms, which shall be kept open and accessible during working-hours and during the intervals between working-periods, and also a separate room for drying clothes. The dressing-rooms shall contain benches and individual lockers, shower-baths, with hot and cold water, and sanitary water-closets, and shall be kept properly heated, lighted, and ventilated.

(9) If the maximum air pressure in such work exceeds seventeen pounds, provide and maintain at least one double compartment hospital-lock; such lock shall be at least six feet high inside measurement, and be suitably floored; it shall be equipped with inside and outside air-gages and timepieces, and a telephone with proper connections, and shall contain benches and proper surgical and medical equipment; it shall be properly heated, lighted, and ventilated.