The sole authority, under which the mayor and aldermen of Cambridge have the right to assess landowners with any part of the expense incurred in the construction of sidewalks, is given by the St. of 1863, c. 191, and must of course be exercised in strict conformity with the terms of that statute. It provides that, whenever .they shall deem it expedient to construct sidewalks in any street of said city, they are authorized to construct such sidewalks with edgestones, and in front of buildings or occupied premises to cover the same with bricks or flat stones, and the expense of such edgestones and covering materials shall be assessed upon the abutters in just proportions.
The vote, under which the proceedings in this case have been had, provides for a sidewalk from Harvard Square to the end of the bridge connecting Cambridge and Boston. It is treated in all the preliminary proceedings, and in the final assessment, as a continuous and single sidewalk, but it is really a sidewalk part of which is in Harvard and part in Main Street. *We do not undertake to decide what weight we should attach to any objection on this account, if it were merely the case of one single street called by different names in different portions of its course or length. But Harvard Street and Main Street are two entirely distinct and separate highways, which, although they unite at one point, yet form two lines of travel nearly parallel to each other for about two miles. We do not think that the statute was intended to give the mayor and aldermen the power to include sidewalks in two different streets in one single assessment. If two streets may be so assessed, it is difficult to see why three or more may not be included in one single assessment, or why all the sidewalks in the city may not be included in one comprehensive assessment.
*355It was evidently intended by the legislature that the case of each street should be considered separately, and with a view to its own special circumstances. Each estate is liable to assessment, not necessarily for the expense of the edgestones and covering materials laid down on that portion of the sidewalk upon whicn it adjoins or fronts, but according to a just proportion of the collective amount of all that kind of expense incurred on the same side of the same street. We cannot know that this proportion might not be very different if other streets were to be included in the same assessment. It may be that practically there would be no danger of any injustice or inequality in the assessment; but the legislature have only given to the board of aldermen a limited authority over the subject matter. The power to treat two sidewalks in two distinct streets .as one, for the purposes of assessment, is not given by the statute.
As this objection to the assessment is insuperable, we have not found it necessary to consider others that have been urged by the plaintiff. Judgment for the plaintiff.