Appeal on substantial question of law limits appellate review to formulated legal issues and procedural compliance. Statute permits appeals against certain wealth-tax orders to a superior court within a prescribed period, with possible extension for sufficient cause; appeals from the tribunal are competent only when a substantial question of law is involved, which the court will formulate, confine the hearing to, decide with reasons, and direct implementation by the assessing authority on a certified judgment, with procedural rules of civil procedure applying as far as practicable.