PER CURIAM:
The sole claim raised on this appeal is that the trial judge erred in charging the jury that if they found defendants aided and abetted certain aliens in concealing from the Immigration and Naturalization Service the fact that the "marriages" which these aliens had contracted with American citizens were made solely to enable them to obtain immigrant visas not otherwise available and not with the intention that the parties would live together or perform the usual obligations of marriage, this would constitute aiding and abetting the concealment of a material fact from an agency of the United States.
The proposition that materiality is a question of law for the court is well settled. United States v. Marchisio, 344 F.2d 653, 665 (2 Cir. 1965); United States v. Ivey, 322 F.2d 523, 529 (4 Cir.), cert. denied, 375 U.S. 953, 84 S.Ct. 444, 11 L.Ed.2d 313 (1963). It is also clear that the concealed facts were of the essence, since the immigrant visas were available only to aliens whose marriages to Americans were bona fide. The appeal is dismissed as frivolous.