The Gen. Sts. c. 46, § 1, provide that “ where buildings or fences have been erected and continued for more than twenty years, fronting upon or against a highway,” “ and from the length of time or otherwise the boundaries thereof are not known, or cannot be made certain by the records or by monuments, such fences or buildings shall be deemed and taken to be the true boundaries thereof.” This clause in the General Statutes, and in the Rev. Sts. e. 24, § 61, from which it was taken, speaks indeed of cases in which the boundaries “ are not known or cannot be made certain,” &c. But the meaning is that they must both be unknown and incapable of being made certain, in order to justify a resort to the actual line of buildings and fences as the controlling guide. This is made manifest by referring to the earlier statutes, in which the clause originated. The contingency, as described in the St. of 1786, e. 67, § 7, was, if the breadth “ is not known or can be made certain,” &c., and in the Prov. St. of 1734 (7 Geo. II., Anc. Chart. 494) “ is not known, nor can be made certain,” &c. It is only where the boundaries are not known, and the more definite and direct means of proof by records of the laying out or monuments established to mark the boundaries fail, that the statute authorizes the line of use and enjoyment as shown oy buildings or fences by the side of the highway to be assumed as fixing its legal limits. Sprague v. Waite, 17 Pick. 309. Plumer v. Brown, 8 Met. 578. Wood v. Quincy, 11 Cush. 487. Holbrook v. McBride, 4 Gray, 215. Pettingill v. Porter, 6 Allen, 349.

*529In the instructions given to the jury in the present case, several clauses, apparently extracted from the opinion of Mr. Justice Dewey in 11 Cush. 496, were used with such additions and in such a connection, as in our judgment to be calculated to mislead the jury. They were instructed that buildings which had been erected and continued for twenty years, fronting on the way, must be presumed to be the line of the highway in. either of two alternatives. 1st, “ if there is no evidence of any other known boundary, or,” 2d. “ the boundary cannot be made certain by any other known monument.” This instruction would lead the jury to understand that if no evidence of any other known boundary had been introduced, they were obliged to take the line of the buildings as the true limit, although the boundary might have been made certain by evidence of other monuments or records and there was no evidence in the case tending to show that it could not have been so made certain. For this reason the defendants are entitled to a new trial. ¡Exceptions sustained.