The sled may have been the first land vehicle used by mankind. Also called a sledge, it is a vehicle with parallel runners instead of wheels that is dragged or pushed and is used to convey a load, especially over snow and ice. Probably the most primitive sled was made of animal skin onto which early man placed his load, usually a dead animal, and dragged it using vines or ropes of some kind. Dragging a heavy load is always easier than carrying it any distance. The true sled with some type of runners is thought to have evolved from the primitive "travois" which was composed of either a single branch of a tree or two wooden poles, one end of which dragged along the ground while the other end was supported or tied to the person or animal pulling it. The load being carried or dragged by...