The hole in the top of the upside-down pot is covered with the metal casing leftover from one of the tea lights. Then the pot is covered by a second, larger pot and the hole in the bigger flower pot is left uncovered. This system works because the candles produce gases full of heated particles that are captured and channeled through the pots. As hot gas particles are lighter than the air, they will rise up through the top into the colder area. What will then be caused is the cold air to fall into the warm areas and create a convection cu