Few people know about what a long way it took the lamp glass before it reached its modern form. A long row of thousands of years people used to light the flame, without resorting to the services of the glass. It took the genius of Leonardo da Vinci (1452-1519), to do this important improvement of the lamp. But Leonardo was surrounded by the flames, not glass, and metal tubing, it took another three centuries before had thought of replacing metal pipes transparent glass cylinder. As you can see, lamp glass - the invention worked on dozens of generations.
What is its purpose?
Hardly all ready the correct answer to this very natural question. To protect the flame from wind - only a minor role in the glass. The main effect of an increase in the brightness of the flame, the acceleration of the combustion process. The role of the glass is the same as the furnace or the smokestack: it increases the flow of air to the flame, enhances the "cravings".
Will look into this. The column of air inside the glass, is heated by the flame is much faster than the air surrounding the lamp. Negresses and becoming therefore lighter air by Archimedes ' principle is popped up heavier unheated air that comes from the bottom through the holes in the burner. This establishes a constant flow of air from the bottom up, over, continuously discharge the combustion products and bringing fresh air. Than the glass, the greater the difference in weight of the heated and unheated air column and the more energetic is the fresh air, and therefore, accelerates combustion. Here is the same as in the high factory chimneys. Therefore, these pipes are so high.
It is interesting that even Leonardo clearly imagined these phenomena. In his manuscripts we find the following entry: "Where there is fire, there is around him and formed an air current: it supports and strengthens".