Similarly, this last remark with regard to the thinning of the heels of the shoe will apply to a shoe with too broad a web. As the thinning of the shoe proceeds with wear, the inner portion of the thinned branch is bent up on to the sole, and again inflicts the injury. The matter of bearing is also of importance when considering the causation of corn. In a previous chapter we have already described the correct bearing as that which includes the whole of the lower margin of the wall and the white line, and just impinges on the sole. Any marked deviation from that will, if long continued, be followed by injury to the foot. With the bearing surface of the shoe too narrow--in contact with the wall solely, or perhaps only a portion of it--it is evident that a large proportion of the foot that should properly bear weight is thrown out of action. A heavy strain is imposed on the white line, and undue descent of the sole and contraction of the heels brought about. Again the result of this is compression and bruising of the tissues around the seat of corn. With its bearing surface too wide, the shoe immediately exerts direct pressure upon the sole with every movement of the animal. The sole normally is not made to receive this, and harm is bound to result. Among other ill-fitting shoes we may mention the one with branches too short, and the one with the extremities of the branches too pointed. In the first case, as wear of the shoe proceeds, the thinned end is far more likely to turn in under the seat of corn than is a shoe with branches of ordinarily correct length. It is evident in the second case that the pointed branch, when thinned, is a more dangerous agent than the branch which is nearer the square at its end. The matter contained in the first half of the foregoing paragraph explains in a large measure the rarity of corns in the hind-feet. Here there is nothing to prevent a shoe with branches of full length being used. The correct bearing is thus maintained, even with a shoe excessively thinned with wear, and the liability to injury from it decreased. An exception is to be found in the case of a feather-edged shoe, such as is used to prevent cutting or brushing. The thinning by wear from above to below of the branch already purposely thinned from side to side leads to the formation of a thin and narrow piece of iron admirably calculated to bend over and injure the sole. Even with a shoe of correct length, with a flat-bearing surface at the heels, and other conditions favourable to correct application, evil may still result from the shoe itself being made too narrow. As a result of this, the branch of _each_ side is set too far under the foot, with consequent injury to the sole. This is, of course, sheer carelessness on the part of the smith. When practised, however, it is not easy of detection, as in all cases the foot is rasped down to cover what has been done. In other words, the foot is made to fit the shoe and not the shoe the foot.