their use on either is but temporary projecting beyond the surface of the shoe, and opposing but a limited surface to the ground, their duration is limited, and when they are worn off, the foot, though in a better position, has nothing to prevent it from slipping on pavement.
For very many years inventors have endeavoured to remedy the defects of calkins in various ways. Indeed, the very earliest specimens of hoof-armature show us that the primitive farriers were no mean adepts in providing their steeds with a 'biting' foot-hold. The nails that fastened on the shoes had large semicircular heads that projected beyond the lower face of the metal on a level with the calkin, and were supported in the oval cavities of the shoe; forming, together with the calks, no less than eight catches—all powerful aids in aiding progression under certain circumstances, and guaranteeing a secure support.
Fiaschi and Blundevil give us more modern examples in their way; the 'catches' of which they speak, however, being notches in a raised welt on the border of the shoe.
In this century, many plans have been adopted; the iron or steel employed being, in a number of instances, rolled by machinery, and generally channelled into grooves or concavities. The most successful of these attempts to fabricate shoes to prevent slipping appears to be that adopted by Mr Gray, of Sheffield. The bars of iron and steel from which his shoes are made are grooved up the middle by either one or two cavities, or notched in various ways. These ridges and teeth are extremely hard, the shoes being tempered after they are forged; consequently they can be made lighter than Rodway's shoes, which were also made from rolled bars.
