Having decided that the order is not appealable, and the case not being before us on appeal, it follows that the petition must be denied. This court has the power to issue the writ only in aid of its appellate jurisdiction. Section 12, Act March 3, 1891, c. *170517, 26 Stat. 829 [U. S. Comp. St. 1901, p. 553], to establish Circuit Courts of Appeals; United States v. Young, 94 U. S. 258, 24 L. Ed. 153.