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A Roman candle is a traditional type of firework that ejects one or more stars or exploding shells. Roman candles come in a variety of sizes, from small 6 mm (1/4") diameter for consumers, and up to 8 cm (3") diameter in professional fireworks displays. Roman candles originated in Italy.〔(【引用サイトリンク】url=http://dictionary.reference.com/browse/roman%20candle )〕 They are banned in some countries as they have a tendency to cause accidents due to users of the firework not knowing how to use them properly. Roman candles are illegal to possess and set off in the U.S. states of New York, New Jersey, Massachusetts, Minnesota, Rhode Island, and Delaware.〔(【引用サイトリンク】url=http://www.pyrouniverse.com/statelaws.htm )〕 == Construction and ignition == Roman candles are fireworks constructed with bentonite, lifting charge, pyrotechnic star, black powder, and delay charge. The device is ignited from the top, which should be pointed into the sky, away from people. The delay powder is packed tightly in the tube, so that the flame cannot reach around the sides of the plug of delay composition. It therefore burns slowly; as it is consumed, the flame moves down through the tube. When the flame reaches the topmost pyrotechnic star, the star is ignited. Because the star fits loosely in the tube, the fire spreads around it and ignites the lift charge. The lift charge burns quickly, propelling the star out of the tube. In doing so it also ignites the layer of delay powder beneath it, and the process repeats. There are several variations on this: * Many Chinese Roman candles use clay instead of delay powder and run a length of fuse down the inside of the candle to time the lifts. * Larger Roman candles (three-inch diameter or more) will usually add more lift to the highest layers and less to the lower layers in order to cause the stars to lift to the same altitude. This is due to the shorter length of tube available for accelerating the higher stars (see firearms internal ballistics). * Some very large Roman candles will load comet shells instead of stars. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Roman candle (firework)」の詳細全文を読む スポンサード リンク
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