Fig. 17.
In [Fig. 17] is shown the foot on its ground surface and from the side. The parallel lines are quite arbitrary, but assist in explaining how the proportion of the foot is to be attained. Both sides of the foot are of the same height. The bearing surface just meets the middle line. All the lines at coronet, heel, and toe, are at right angles to the perpendicular line. The side view shows the proportionate height of heel and toe, and the slope of the wall in front. Compared with [Figs. 22] and [23] deviations from proportion are seen.
These conditions are not attainable with all feet, but the prudent farrier does the best he can under the circumstances. It is easy to make the frog touch the ground by over-lowering the heels, but this is only introducing one evil in attempting to avoid another. Some feet have naturally a long toe with an excessive slope of the front part of the wall. To hide this defect a farrier may "stump up" the toe and leave the heels too high, but he does so at the expense of the horse's foot. Each foot requires treating with full knowledge of the form best adapted to its natural formation, and most capable of carrying a shoe.
The Instruments used to prepare a foot for shoeing are a rasp, a drawing knife, and a toeing knife.
The rasp is the most indispensable. It should be sixteen inches long, proportionately broad, and one part of it should be a file-surface. The shorter, narrow rasps do not afford all the advantages a farrier should possess to enable him to do the best work. To strike an even all-round level bearing surface on a hoof a farrier requires a large rasp, just as a joiner must have a large plane to produce a level surface on wood. Harm may be done by the careless use of a rasp, and a bearing-surface spoiled by the over-reduction of horn at one place. This fault may be aggravated by attempts to mend it, if such attempt take the form of further reduction of the whole hoof on a foot where horn is deficient.
The drawing knife is a comparatively modern instrument which replaced a tool called the buttress. A drawing knife is formed with great skill for the purpose of paring out the concave sole of the hoof, and has done infinite harm. In the days which have now almost passed away, when it was thought the proper thing to make the hoof look clean, smooth, and pretty, the drawing knife was the chief instrument in the preparation of the foot. Now, when nearly all men know that the stronger the sole and frog of the foot can be preserved the better for the horse, this knife is less used—and the less the better. The doorman, preparing a foot for the fireman to fit a shoe to, should not use a knife at all. The man who fits the shoe requires a knife to remove occasional little prominences of horn which are liable to cause uneven pressures or which are in the way of a properly fitted shoe—as, for instance, the edge of the wall to make way for a clip, or the angle of sole at the heel to prevent uneven pressure by the shoe.
The toeing knife usually consists of about a foot of an old sword-blade. This knife is held and guided by one hand of the farrier, whilst with the other it is driven through overgrown horn by the hammer. Skilfully used it is unobjectionable, and for the large strong hoof of heavy draught horses it saves a great deal of time and labour. For the lighter class of horses it is unnecessary, and for weak feet with a thin horn covering it is dangerous.