vbl. sb. [f. as prec. + -ING1.] † Assurance, confirmation (obs.). (Now gerundial: see ASCERTAIN v. 5.)
1685. Baxter, Paraphr. N. T., Acts i. 9. The sight of Christ’s Ascension must needs be … an ascertaining of the Apostles Faith.
1835. Macready, Remin., I. 472. On ascertaining the time.
