(1) Employ one or more licensed physicians as medical officers who shall be present to render medical assistance at all necessary times at the place where such work is in progress and who shall perform such other duties as are imposed on them by this act.

(2) If the maximum air pressure in such work exceeds seventeen pounds employ one or more registered nurses or one or more competent persons, which persons shall be selected by the medical officer and be certified by him to be competent by actual experience to handle cases of compressed-air illness. The nurses or persons so employed shall have charge of the hospital-lock provided for in this act, and may also have other duties of a clerical nature, exclusive or timekeeping, such as will not require their presence elsewhere than at the hospital-lock and such as they may leave at any time their service at the lock is necessary.