SPECIAL DEPARTMENTAL RULE NO. 2.
No substitute shall hereafter be employed in any Department; and the head of any Department in which substitutes are now employed may appoint any of such substitutes to take the place of his principal, or to any place of lower grade: Provided, That no substitute shall be appointed as herein authorized until he shall have passed an appropriate examination by the Civil Service Commission and his eligibility shall have been certified by said Commission to the head of the Department in which he is employed.
Approved, August 3, 1888.
Grover Cleveland, Executive Order Online by Gerhard Peters and John T. Woolley, The American Presidency Project https://www.presidency.ucsb.edu/node/205502