A candle is placed inside a chimney with a metal vane dividing it into two parts. The vane ensures that hot air rises on one side and cooler air is drawn in from the other, maintaining a continuous airflow that keeps the candle burning. Removing the vane disrupts this convection process, causing the candle to extinguish due to a lack of oxygen. This setup illustrates how convection currents are crucial for maintaining airflow and the principles of heat-induced air movement.