Horse collar of the Oseberg ship burial). The problem with a breastcollar harness was that the actual shafts of the cart, chariot, or other vehicle are attached to a surcingle around the barrel of the horse. The breastplate primarily kept the surcingle from slipping back, not as the primary pushing object. This results in the horse literally pulling the load, a less efficient use of the animal. The modern breastcollar has traces which transfer the pull directly from the breastcollar, but a horse collar still is more effective for pulling heavy loads. After the breastcollar harness, the next and final evolutionary stage
Girth (graph theory) coloring must be small and which therefore requires at least colors in any coloring. The odd girth and even girth of a graph are the lengths of a shortest odd cycle and shortest even cycle respectively. The circumference of a graph is the length of the "longest" cycle, rather than the shortest. Thought of as the least length of a non-trivial cycle, the girth admits natural generalisations as the 1-systole or higher systoles in systolic geometry. Girth is the dual concept to edge connectivity, in the sense that the girth of a planar graph is the edge connectivity of its