The so-called _interfering shoes_ (Figs. 154 and 155) are worthy of recommendation only for hoofs of the base-narrow position. The interfering branch, whose greater thickness raises the inner wall, which is often too low, is to be so shaped and directed that the hoof will project somewhat beyond it. _This interfering branch must be made and shaped in accordance with each individual case._ The holes in the interfering branch should be punched somewhat finer (nearer the edge) than usual. Interfering shoes in which the nail-holes, with the exception of the inner toe nail-hole, are placed in the outer branch, are called “_dropped-crease interfering shoes_” (Fig. 156). Such shoes are not recommended for hind hoofs that are decidedly toe-wide (toe-cutters); in such cases better results will be obtained by using a shoe, either with or without heel-calks, whose inner branch is straight and without nails along the striking region, and is fitted wide (full) at the quarter. The inner branch should be from one-fourth to three-eighths of an inch longer than the outer. The inner heel-calk should be higher than the outer, and the end of the outer branch should be as base-narrow as it can be made (fitted close) (Fig. 157). In order to prevent shifting of an interfering shoe, a side-clip should be drawn up on the outer branch (_a_). There is no manner of shoeing that will prevent interfering which is caused by improper harnessing, crooked hitching, or weariness. The simpler and the _lighter_ the shoes the less will horses interfere. CHAPTER V. WINTER SHOEING. All shoes whose ground-surface is provided with contrivances to prevent slipping upon snow and ice are called winter shoes. [Illustration: FIG. 158. An ice-nail, frost-nail.] These various contrivances are produced by several processes called “methods of sharpening.” All methods may be gathered into two groups,—namely, _practical_ sharp-shoeing and _impractical_. Only the first will be considered. The durability of sharpened shoes depends partly upon whether they are made of steel or iron, and partly upon the nature of the ground in winter. If the ground is continuously covered with a thick layer of snow, whatever method of sharpening is followed, the shoes =stay sharp=; if, however, the winter is open, changeable, with more bare ice than snow, no method of sharpening, whatever it may be, will last long; the shoes will =not stay sharp=. For these reasons no method of sharpening which fulfils all conditions satisfactorily has yet been discovered. The simplest and at the same time the least durable method of sharpening is: 1. That by means of =ice-nails= or =frost-nails= (Fig. 158). One or two nails are drawn from each branch of the shoe and replaced with ice-nails.