Using the thermal expansion and contraction due to cooling. The initial cold water on the bottom glass bulb. Add ground coffee, powdered glass cone on the cylinder. The bottom of a glass funnel with a rubber stopper and filter coffee off. The heat from the light bulb or the gas chambers at the bottom until the water starts to boil. Open rubber hot water through ground coffee into the filter and funnel top. Use a spoon to stir coffee break. By careful not to filter coffee powder flip otherwise have slipped into the water and coffee. When hot water is moving into a conical top end. Then remove from heat immediately Coffee cools Then flows through the filter back into the glass bulb. Then pour a cup of coffee served in the normal way. Maker is suitable for coffee each glass. The ability to maintain taste and aroma to the full.