D owned waterfront property and built a wharf on the tidal flats from the high- to low-tide mark. D was indicted for having erected and built a wharf over and beyond certain lines, described as the commissioners' lines, into the harbor of Boston. The wharf did not interfere with navigation. The Act declared that the lines were established as the lines of the channel of the harbor of Boston, beyond which no wharf or pier should ever thereafter be extended into and over the tide water of the commonwealth. At the trial both P and D stipulated to the following: “D is, and for more than thirty years past has been, seised of an estate consisting of upland and flats belonging thereto, and through which the sea ebbs and flows to and from a bay above. In 1843, D began to build a wharf on his said flats and constructed the northerly wall thereof from his upland nearly to the channel, and then filled in and constructed said wharf, but did not complete it until the commissioners' line of 1847 had been established, after which he built the triangular piece set forth in the indictment, which forms a part of the wharf as originally commenced by him. This triangular piece is beyond said line, but is built on D's own flats; it is not one hundred rods from the upland, is not below low water mark, is no injury to navigation, and is not so far beyond the commissioners' line or so near the channel as the northerly wall of the wharf was built in 1843.” The jury returned a verdict of guilty; and the presiding judge, being of opinion that the questions of law arising in the case were so doubtful and important as to require the decision of this court, with the consent of the defendant, reported the case for the purpose of presenting those questions.