http://www.dailymail.co.uk/travel/travel_news/article-4095234/The-Houses-Monuments-Pompeii-presents-colour-lithographs-Fausto-Felice-Niccolini-19th-century.html In illustration four, let's assume for a moment that the elaborate wiring that leads from the black boxes in the lower right and left hand corners is not decoration. By actuating the two heavy copper switches , the electricity generated by cranking a large ball of amber inside fur in those boxes the charge will be released. Traveling along the green silk insulated line it then causes those numerous lamps to light up as the electric spark ignites the oil, impressive lightning to crackle between the crossed spears, and the two large flat bowls full of flash powder (at that time made from fungus spores) at the top to blow like the pyrotechnics at a rock concert. The two women on either side are holding soaking wet white woollen blankets for fire control. Zeus sitting in the middle gives his little speech and then waves his speak to signal time for the show. BOOM! They would have to crank it back up again if they wanted another display, so it probably ended a big event after sunset, much like the burning of the burning man does now.