law of diminishing returns. A concept in economics that if one factor of production (number of workers, for example) is increased while other factors (machines and workspace, for example) are held constant, the output per unit of the variable factor will eventually diminish.
History of glass. The history of glassmaking can be traced back to 3500 BCE in Mesopotamia, but Mesopotamians may have created second-rate copies of glass objects from Egypt, where this complex craft actually originated. Other archaeological evidence suggests that the first true glass was made in coastal north Syria, Mesopotamia or Egypt.
Soda fountains as we know them today weren't widely used or known until the 1830's and 40's when John Matthews and John Lippencott began producing them in the United States. So that's basically WHEN carbonated beverages were invented...now let's have a chat about WHY! Carbonated mineral water (which I mentioned and deviated from earlier) has pretty much throughout all of written history been a staple health food.