Classical element to use the term "element (στοιχεῖον, "stoicheion")" in reference to air, fire, earth, and water. The ancient Greek word for element, "stoicheion" (from "stoicheo", "to line up") meant "smallest division (of a sun-dial), a syllable", as the composing unit of an alphabet it could denote a letter and the smallest unit from which a word is formed. A similar alphabetic metaphor may be the origin of the equivalent Latin word "elementum" (from which the English word comes), possibly based on the names of the letters 'l', 'm', and 'n', though the validity of this idea is debated. In his "On
Dual ignition Dual ignition Dual Ignition is a system for spark-ignition engines, whereby critical ignition components, such as spark plugs and magnetos, are duplicated. Dual ignition is most commonly employed on aero engines, and is sometimes found on cars and motorcycles. Dual ignition provides two advantages: redundancy in the event of in-flight failure of one ignition system; and more efficient burning of the fuel-air mixture within the combustion chamber. In aircraft, redundancy is the prime consideration, but in other vehicles the main targets are efficient combustion and meeting emission law requirements. A dual ignition system will typically provide that each cylinder has