The parties in this case reduced their contract to writing, and by that they are bound, unless there was fraud- ■or mistake — there is no pretence of either. The contract shows that the parties did not know exactly the quantity of land — they ■estimated the quantity and agreed upon a certain rent in gross, not by the acre. It was incompetent for the defendant to prove there was a less quantity of land, without showing also an agreement to deduct, if that was found to be the case. The evidence, therefore, ■should have been rejected. The judgment and proceedings since the issue are reversed, and the cause remanded for further proceedings.