Defendant appeals from a judgment of a City Magistrate, sitting as a Court of Special Sessions of the City of New York, Borough of Brooklyn, convicting her of violating sections 8, 170, 300, 301 and 302 of the Multiple Dwelling Law, in that she unlawfully altered and converted a private dwelling into a multiple dwelling for use by four families without a permit. Defendant was sentenced to pay a fine of $250 or to serve thirty days in the City Prison. The fine was paid. Judgment reversed on the law, fine remitted, and a new trial ordered. At the trial defendant offered in evidence (a) two letters from the department of housing and buildings, and (b) three certificates issued by the County Clerk of Kings County, which documents defendant claims purported to show that the premises were occupied by three separate families prior to the enactment of the Multiple Dwelling Law, and by reason thereof were not subject to the provisions of the statute subsequently enacted. The court excluded this offer of proof. While it was proper to exclude the two letters from the department as being irrelevant, we hold, without passing upon the conelusiveness of these exhibits, that the refusal of the court to admit into evidence the documents from the County Clerk’s office was substantial error. Nolan, P. J., Wenzel, MaeCrate, Beldock and Murphy, JJ., concur.