To set aside his conviction of escape from the District of Columbia Reformatory at Lorton, Virginia, in violation of 18 U.S.C. § 751(a), Billy Austin Bryant assigns error to the trial court’s reception at trial of a prosecution witness’ answer on cross-examination. Assuming the ruling was erroneous, it was harmless. Certainly it does not justify reversal of the conviction, which is supported by copious evidence. Rule 52(a) F.R.Crim.P.

Affirmed.