The litter is a class of wheelless vehicles, a type of human-powered transport, for the transport of people. Smaller litters may take the form of open chairs or beds carried by two or more carriers, some being enclosed for protection from the elements. Larger litters, for example those of the Chinese emperors, may resemble small rooms upon a platform borne upon the shoulders of a dozen or more people. To most efficiently carry a litter, porters either place the carrying poles directly upon their shoulders or use a yoke to transfer the load from the carrying poles to the shoulders. Definitions A simple litter consists of a sling attached along its length to poles or stretched inside a frame. The poles or frame are carried by porters in front and behind. Such simple litters are common on battlefields and emergency situations, where terrain prohibits wheeled vehicles from carrying away the dead and wounded. Litters can also be created quickly by the lashing of poles to a chair. Such litters, consisting of a simple cane chair with maybe an umbrella to ward off the elements and two stout bamboo poles, may still be found in Chinese mountain resorts such as the Huangshan Mountains to carry tourists along scenic paths and to viewing positions inaccessible by other means of transport. A more luxurious version consists of a bed or couch, sometimes enclosed by curtains, for the passenger or passengers to lie on. These are carried by at least two porters in equal numbers in front and behind, using wooden rails that pass through brackets on the sides of the couch. The largest and heaviest types would be carried by draught animals. Another form, commonly called a sedan chair, consists of a chair or windowed cabin suitable for a single occupant, also carried by at least two porters in front and behind, using wooden rails that pass through brackets on the sides of the chair. These porters were known in London as "chairmen". These have been very rare since the 19th century, but such enclosed portable litters have been used as an elite form of transport for centuries, especially in cultures where women are kept secluded. Sedan chairs, in use until the 19th century, were accompanied at night by link-boys who carried torches. Where possible, the link boys escorted the fares to the chairmen, the passengers then being delivered to the door of