This court has recently had occasion to decide that the assessment of a certain proportion of the expense incurred by laying out, widening or improving a public street or highway, upon such estates as receive any special benefit or advantage thereby, is a tax which is authorized by law. Dorgan v. Boston, 12 Allen, 223. Harvard College v. Aldermen of Boston, 104 Mass. 470. Codman v. Johnson, Ib. 491. Walker v. Whittemore, 112 Mass. 187. This tax, although special and local in its character, must, nevertheless, be assessed upon all the estates so benefited and liable to be assessed, in such a manner that each shall bear its just proportion, and no more. The law provides that it shall be assessed by a responsible board of officers, and in the *531execution of that duty they act in a quasi judicial capacity. This is a public duty or trust, the performance of which cannot be dispensed with or abridged by any agreement of the city. Bell v. Boston, 101 Mass. 506. Brimmer v. Boston, 102 Mass. 19. Sceery v. Springfield, 112 Mass. 512. Barker v. Chesterfield, 102 Mass. 127. Lowell v. Simpson, 10 Allen, 88. Neither can the performance of that dirty be delegated by the board to anybody else, but it must be wholly their own act. It would be, if possible, a still greater departure from their legitimate authority, to undertake to authorize any one individual to select one of the benefited estates from the whole number, and make it the subject of a separate settlement by virtue of which it is to be omitted from the assessment.
It follows, therefore, that the agreement which the plaintiff says it made with the chairman of the committee on streets cannot have any effect in relieving its estate from the assessment.
Bill dismissed, with costs.