Section, acts Mar. 3, 1875, ch. 132, § 7, 18 Stat. 450; July 31, 1894, ch. 174, §§ 3, 7, 28 Stat. 205, 206; June 10, 1921, ch. 18, title III, § 304, 42 Stat. 24, directed that copies of contracts made by Commissioner of Indian Affairs, or any other officer of Government for the Indian Service, be furnished to General Accounting Office prior to payment.