Comparison of secondary and fundamental standards.
Section 281
SEC. 281. Comparison of secondary and fundamental standards. — The comparison of the secondary and fundamental standards shall be made in the Bureau of Science at the instance of the Collector of Internal Revenue. When found to be sufficiently accurate, the secondary standard shall be distinguished by a label, tag, or seal, and shall be accompanied by a certificate showing the amount of its variation from the fundamental standard. If the variation is of sufficient magnitude to impair the utility of the instrument, it shall be destroyed in the Bureau of Science.