The Commissioners shall, during the Construction or Repair of any of the Streets vested in them, and during the Construction or Repair of any Sewers or Drains, take proper Precaution for guarding against Accident, by shoreing-up and protecting the adjoining Houses, and shall cause such Bars or Chains to be fixed across or in any of the Streets, to prevent the Passage of Carriages and Horses while such Works are carried on, as to them shall seem proper; and the Commissioners shall cause any Sewer or Drain pr other Works, during the Construction or Repair thereof by them, to be lighted and guarded during the Night, so as to prevent Accidents; and every Person who takes down, alters, or removes any of the said Bars or Chains, or extinguishes any Light, without the Authority or :Consent of the Commissioners, shall for every such Offence be liable to a Penalty not exceeding Five Pounds,