Remove the glass chimney from an old lantern. Soak in lukewarm water to remove all the old stains. Allow to dry. Feed a length of electric cable (with a light fitting at one end) through the mouth of the glass chimney. Glue the light fitting to the mouth of the chimney with a glue gun. Allow to dry. When completely dry, wire an electric plug to the end of the cable emerging from the mouth. Finally fit a bulb into the light fitting.