so hot that it scorched or set fire to materials that it brushed. The incendiary liquids of the ancient and medieval periods were also developed, and have their modern equivalents. World War I saw the development of the flamethrower, a modern version of the Byzantine siphons, which used gas under pressure to squirt a mixture of inflammable oil and petrol, ignited by a burning taper. Similarly, the carcass projectile found new use in the Livens Projector, a primitive mortar that could throw a large canister of inflammable liquid (it was soon used for poison gas instead). Technology improved throughout the 20th century, and the latter half saw the development and use of napalm, an incendiary liquid formed in part from naphtha, which was the main ingredient of the Arabic "naft". Flames continued to be used for defensive light until artificial lights were developed. At the Siege of Badajoz in 1812, the French defenders flung down burning "carcasses" of straw so that the attacking British might be seen. Like the sieges of old, the British were met by incendiary weapons, but now these took the form of explosive grenades, mines and powder barrels as well as the enemy's guns. Specific weapons from the ancient and medieval periods continued to develop, and many have modern equivalents. Rocket technology, originally trialled by the Mongols, Indians and the Chinese, amongst others, was improved by the 19th century; one example was the incendiary Congreve rocket, which had a tail, a fuse, and a powder charge (saltpetre, sulfur and carbon) inside a hollow shell. Grenades continued to develop, although still retaining some aspects of their medieval equivalents. The grenades carried on board British Royal Navy ships in the late 18th century and early 19th century were constructed from hollow cast iron, filled with gunpowder; the fuse was a hollow wooden tube filled with combustible material. During World War I, grenades were still occasionally launched by ballistae. The use of some weapons continued with little change. The Koreans used fire arrows against the Japanese at the Battle of Hansan Island in 1592. At Trafalgar, in 1805, the British ship Tonnant shot wads covered in sulfur, which set fire to the Algésiras. Fireships were used in later periods. In 1588, the English sent fireships loaded with gunpowder, pitch and tar amongst the anchored Spanish Armada; the Spanish fleet broke formation, setting them up for the later battle. The