Section 7, act Mar. 4, 1923, ch. 251, 3, 42 Stat. 1453, authorized collectors, comptrollers, surveyors, and appraisers to appoint assistants, and collector at New York to appoint a solicitor to collector, all such appointments subject to approval of Secretary of the Treasury. Section 8, R.S. 2629; acts Mar. 3, 1905, ch. 1413, 1, 33 Stat. 983; Mar. 4, 1923, ch. 251, 4, 42 Stat. 1453, set forth procedure for filling a vacancy in office of a collector, comptroller, surveyor, or appraiser. Section 9, R.S. 2625, act Mar. 4, 1923, ch. 251, 3, 42 Stat. 1453, provided for performance of collectors duties in case of his disability. Section 10, R.S. 2630; acts Mar. 4, 1923, ch. 251, 2, 3, 42 Stat. 1453; Jan. 13, 1925, ch. 76, 43 Stat. 748, provided that in cases of occasional and necessary absence, or of sickness, any collector could exercise his powers and perform his duties by deputy. Section 11, R.S. 2632; act June 17, 1930, ch. 497, title IV, 523, 46 Stat. 740, provided that in cases of occasional and necessary absence, or of sickness, every comptroller and surveyor could, respectively, exercise and perform his functions, powers, and duties by deputy.