The secretary of labor may appoint a person, or persons, having a technical knowledge of bookkeeping, engineering, or other technical subjects involved in any inquiry in which the secretary of labor is engaged, as an examiner for the purpose of taking evidence with relation to such subject. The examiner when appointed shall take an oath to well and faithfully perform the duties imposed upon such examiner, and shall thereafter have the same power to administer oaths, compel the production of evidence, and the attendance of witnesses as the secretary of labor would have if sitting in the same matter. The examiner shall receive such compensation as may be provided by law or as fixed by the secretary.