Ancient Rome and wine Gaul. The Romans established lucrative trading relations with local tribes of Gaul, despite their potential to produce wine of their own. The Gallic tribes paid high prices for Roman wine, with a single amphora worth the value of a slave. From the Mediterranean coast, the Romans pushed further up the Rhone Valley, to areas where olives and figs were unable to grow but where oak trees were still found. As a result of their experience in what is now northeastern Italy, the Romans knew that regions where "Quercus ilex" were found had climates sufficiently warm enough to allow the full
Leyden jar used in demonstrations. The jar is constructed out of a glass cup nested between two fairly snugly fitting metal cups. When the jar is charged with a high voltage and carefully dismantled, it is discovered that all the parts may be freely handled without discharging the jar. If the pieces are re-assembled, a large spark may still be obtained from it. This demonstration appears to suggest that capacitors store their charge inside their dielectric. This theory was taught throughout the 1800s. However, this phenomenon is a special effect caused by the high voltage on the Leyden jar. In the dissectible