16. Revocation of delegations---(1) Every delegation under section 15
 of this Act shall be revocable in writing at will.

   (2) Any such delegation, until it is revoked, shall continue in force
 according to its tenor, notwithstanding that the Commissioner by whom it
 was made may have ceased to hold office, and shall continue to have
 effect as if made by the successor in office of the Commissioner.