When St. 1846, c. 271, was passed, the defendants had purchased the land for their road through the farm that the plaintiff now owns; and as they were not bound to fence it unless by order of the county commissioners, under St. 1841, c. 125, § 1, it is to be presumed that the price included the expense of fencing by the owner. Morss v. Boston and Maine Railroad, 2 Cush. 536. If the statute of 1846 required them to fence it, and relieved the landowner, its operation would be retrospective and unjust. Gerry v. Stoneham, ante, 319. But it applied by its terms only to roads thereafter to be constructed. The defendants had not only purchased the land and located the road, but had partially graded it. If we regard the object of the act, it did not apply to this case. If we disregard its object, and apply it to all roads not completed, very few roads then existing would be exempted from its operation. The first construction is the more reasonable. It was therefore the plaintiff’s duty to keep his fence in repair, and as his neglect in this respect contributed to the injury, he cannot recover. Exceptions overruled.