shall lie just within and above its ground surface, so that in the descent of the sole the frog shall come sufficiently on the ground to enable it to act as a wedge, and to expand the quarters, while it is defended from the wear and injury it would receive if it came to the ground with the first and full shock of the weight.'
With respect to paring the hoof, Youatt commits the most dangerous blunders to be found in his work. Admitting that no specific rules could be laid down, he adds: 'This, however, we can say with confidence, that more injury has been done by the neglect of paring than by carrying it to too great an extent. The act of paring is a work of much more labour than the proprietor of the horse often imagines; the smith, except he be overlooked, will give himself as little trouble about it as he can; and that which, in the unshod foot, would be worn away by contact with the ground, is suffered to accumulate month after month, until the elasticity of the sole is destroyed, and it can no longer descend, and the functions of the foot are impeded, and foundation is laid for corn, and contraction, and navicular disease, and inflammation.
'That portion of horn should be left on the sole, which will defend the internal parts from being bruised, and yet suffer the external sole to descend. How is this to be measured? The strong pressure of the thumb of the smith will be the best guide. The buttress, that most destructive of all instruments, being banished from the respectable forge, the smith sets to work with his drawing-knife, and he removes the growth of horn, until the sole will yield, although in the slightest possible degree, to the very strong pressure of his thumb. The proper thick-
