Peculiarities of the Shoe. They are dependent upon the structure, direction, and position of the leg and hoof, as well as upon the horse’s service and the nature of the ground. Since the shoe is an artificial base of support, and since a proper surface of support is of the greatest importance in preserving the soundness of the feet and legs, careful attention must be given to this matter. Naturally shoes designed for the various forms of hoofs must present equally great and equally numerous differences of form, as well as other peculiarities. =General Properties.= 1. =Form.=—A form corresponding to the shape of the hoof is indispensable in every shoe. Front and hind and right and left shoes should be sharply defined and easily distinguishable. _Front shoes_ must, above all else, be circular _round cut the toe_. _Hind shoes_, on the contrary, should be _round pointed at the toe_, yet not too much so, but as in Fig. 116. 2. =Width.=—All shoes should be wider webbed (more covered) at the toe than at the ends of the branches. The medium width should be about twice the thickness of the wall. [Illustration: FIG. 107. Right front shoe, ground-surface.] [Illustration: FIG. 108. Right front shoe, hoof-surface: _a_, bearing-surface; _b_, concaving, or “seating.”] 3. =Thickness.=—Each shoe should, in general terms, be so thick that it need not be renewed under four weeks. Lungwitz found that the average required thickness is about seven-sixteenths of an inch. Of course, this thickness must be diminished or increased according to the rapidity of wear of the shoe. _Shoes without calks should be of uniform thickness_, unless there are special reasons for making them otherwise. 4. =Length.=—For draft-horses they should be long enough to reach the bulbs of the heel, otherwise shorter, though in other respects they may differ (see “special properties”), but should in all cases completely cover the bearing-surface of the hoof. 5. =Surfaces.=—That part of the hoof-surface of the shoe which is in contact with the hoof (bearing-surface of the shoe, Fig. 109, _a_) should be horizontal and wide enough to cover the wall, the white line, and from a twelfth to an eighth of an inch of the outer edge of the sole. Shoes for large hoofs require a broader bearing-surface than those for small hoofs. The concaving, or “seating” (Fig. 109, _b_), should be made deeper or shallower, according to the nature of the sole. _Shoes for hoofs with strongly arched_ (very concave) _soles, do not require any concaving_ (hind hoofs, narrow fore-hoofs). _The object of concaving is to prevent pressure of the shoe upon the horny sole except at its margin._ [Illustration: FIG. 109. Transverse section of a branch of a front shoe: _a_, bearing-surface; _b_, concaving; _c_, fullering, or “crease”; _d_, nail-hole.] The ground-surface of the shoe should be flat and _perfectly horizontal_, except at the toe, which may be turned upward (rolled toe, “rolling motion”).