Appeal by defendant from a judgment of the Supreme Court, Queens County, rendered June 28, 1973, convicting him of arson in the third degree, upon a jury verdict, and imposing sentence. Judgment affirmed. Although, in the circumstances at bar, it was error to admit the People's expert evidence that three fires attributed to defendant were incendiary in origin ( People v. Grutz, 212 N.Y. 72), the error was insubstantial, for the uncontradicted proof showed that each of the virtually simultaneous fires in two bedrooms and in the basement of the dwelling in question had been caused by the use of a flammable liquid, that each fire had an origin independent of the others and that defendant had confessed to the setting of the fires. Cohalan, Acting P.J., Christ, Brennan, Benjamin and Shapiro, JJ., concur.