: the part of the leg in which the cannon bone is found
Illustration of CANNON
Long-range artillery piece, as distinguished from other big guns such as the howitzer or mortar. Early cannons, appearing in Europe in the 15th century, were smooth-bored and forged of iron, weighed 6,000–8,000 lbs (2,800–3,600 kg) and were loaded through the muzzle. They were mounted on wheeled carriages, which were thrown backward when the cannon was fired. Rifled bores and breechloading were adopted in the later 19th century, and new mechanisms such as the hydraulic buffer absorbed the recoil. Before 1850 ammunition was either cannister, grapeshot, or round, solid cannonballs and black powder, but rifled bores made possible the use of elongated projectiles, which had a longer range. The shrapnel shell was widely used in the 19th–20th century. Modern cannons, of high-grade steel, are towed on split-trail carriages or are mounted on tracked vehicles; a common calibre is 155 mm (6 in.). Many helicopters, airplanes, and naval vessels are equipped with multibarreled, Gatling-type rotary cannons firing 20-mm exploding shells.