The Metropolitan Board of Works shall appoint a Committee for the Purpose of hearing all such. Appeals, as, may be made to the said Board as aforesaid, which Committee, shall, have Power to hear and decide all such Appeals, and the Metropolitan Board of Works shall from Time to Time fill up any Vacancy in such Committee, and the Chairman, of the said Board shall, by virtue of his Office of Chairman, be a Member of the said Committee in addition to the Members appointed by the said Board, and shall preside at all Meetings of such Committee at which he is present; and in case of a Vacancy in the Office of such Chairman, or, in his Absence, some other Member of the Committee shall be chosen to preside, and all the Powers of such Committee, may be exercised by any Three of them, and any Member of such Committee may at any Time resign his Office.