33 U.S.C. § 873
Extra compensation for instrument observers, recorders and other Federal employees for oceanographic, seismographic and magnetic observations
The Secretary of Commerce is authorized to pay extra compensation to members of crews of vessels when assigned duties as instrument observer or recorder, and to employees of other Federal agencies while observing tides or currents, or tending seismographs or magnetographs, at such rates as may be specified from time to time by him and without regard to section 5533 of title 5.