1. The first instruction to which the tenants have taken exception was correct. The jury were instructed that if the parties were in doubt as to a dividing line between them, and fixed the line by a paroi agreement, and occupied according to this agreement for twenty years, it would be binding on the parties, and would settle their rights. This instruction was given without objection. But they were further instructed “ that although the presumption was that such was *496the true line, yet if it could be shown not to be so, such oral agreement and occupation would not bind the parties nor fix their rights, unless the line had been adhered to for the full term of twenty years ; ” and to this exception was taken. The only error suggested by counsel at the argument is, that the jury might have understood the phrase “ adhered to ” as implying the continued agreement of both parties to the occupation; and that any objection made by the demandants, within the twenty years, would prevent the tenants from acquiring a title t>y adverse possession, although they might have occupied peaceably up to the line, under a claim of right. We do not think the language used would bear this construction. The second sentence is merely the counterpart of the former; and the court obviously meant no more than this, that while twenty years’ occupation under a paroi agreement as to boundary would be conclusive, less than twenty years would not. All that “ adhering to the line” would express in that connection, was the occupation according to it which had just been mentioned.

2. The remaining exception raises this question : Whether, if a boundary line has been erroneously run between adjoining owners of land, without fraud, and under a mutual mistake, there being no determination of the line by arbitration or other judicial decision, one party is estopped from claiming his land to the true line, because the other has, with his knowledge, erected buildings or incurred expense in consequence of the mistake ?

We are of opinion that it was rightly held at the trial that there is no estoppel under such circumstances. There is nothing in the case to show that there was any “ standing by,” and permitting the expenses to be incurred without notice, which was the case put in Thayer v. Bacon, 3 Allen, 165. The parties did not even undertake to fix a doubtful line by agreement, but only to point the true boundary as fixed by the deed. The authority of Tolman v. Sparhawh, 5 Met. 469, is therefore direct and conclusive.

The case chiefly relied on by the tenants, Kellogg v. Smith, 7 Cush. 375, is wholly different. There the line in question had *497been referred to as a fixed boundary, and adopted as such for more than a hundred years; and the decision did not rest on the point of estoppel. There being no title acquired by adverse possession, and no estoppel, there should be judgment on the verdict. Exceptions .overruled.