It consists of a brass pipe and a tea candle. First fill the pipe with water. Then light the tea candle. When the water comes to the boil, it turns into steam and seeks to escape. This produces a partial vacuum in the pipe, which in turns sucks in fresh water. The force of the escaping steam being stronger than that of the incoming water, the ship is propelled in a forward direction – for some time, until the flame of the tea candle goes out.