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
Tree girth measurement tree and by extension the girth should be measured with respect to the same base point. This point is fixed at the same location over time as the tree grows. In addition this is a reference point that is present and consistent in all trees no matter the height of the girth measurement. Even if the girth is measured at a non- standard height because of low branching, a large burl, or even on the upslope side of a large girth tree on sloping ground, all heights can still be consistently referenced to this single point present on all trees.