Nothing in Section 3 [50-4-13 N.M. Stat. Ann.] of this act, shall be construed so as to prevent work in excess of ten hours per day in emergency cases; provided that in no one week of seven days shall there be permitted more than seventy-four hours of labor, and provided that work in excess of seventy hours of labor in any one week of seven days, shall be paid for on the basis of time and one-half for such excess.