When in the opinion of the Secretary of the Army the changes of a station of an officer of the Corps of Engineers is primarily in the interest of river and harbor improvement, the mileage and other allowances to which he may be entitled incident to such change of station may be paid from appropriations for such improvements.
(Mar. 3, 1925, ch. 467, § 5, 43 Stat. 1191; July 26, 1947, ch. 343, title II, § 205(a), 61 Stat. 501.)