One Third of the Members first elected as aforesaid of the Metropolitan Board of Works shall go out of Office on the Second Wednesday in June One thousand eight hundred and fifty-seven, One other Third of them on the Second Wednesday in June One thousand eight hundred and fifty-eight, and the remaining Third on the Second Wednesday in June One thousand eight hundred and fifty-nine; and such first elected Members shall determine by Lot among themselves which of them shall constitute the One Third to go out of Office in the Years One thousand eight hundred and fifty-seven and One thousand eight hundred and fifty-eight respectively ; and all Members of the said Board elected to supply any Vacancy occasioned by any Members going out of Office by the Expiration of his Term of Office shall go Out of Office on the Second Wednesday in June in the Third Year next following the Year of his Election ; and every Member of the said Board elected to supply any other Vacancy shall go out of Office when the Term of Office of the Member in whose Place he is elected would have expired by Effluxion of Time.