THE CORONARY RING. THE BARS. 29? 



outer. While it is thin t > yield to the shock, its increased surface gives it sufficient 

 strength. 



On account of its thinness, and the additional weight which it bears, th inner bee 1 

 wears away quicker than the outer ; a circumstance that should never be forgotten by 

 the smith. His object is to give a plane and level bearing to the whole of the crust. 

 To accomplish this, it will be often scarcely necessary to remove anything from the 

 inner heel, for this has already been done by the wear of the foot. If he forgets this, 

 as he too often seems to do, and cuts away with his knife or his buttress an equal 

 portion all round, he leaves the inner and weaker quarter lower than the outer ; he 

 throws an uneven bearing upon it ; and produces corns and sand-cracks and splints, 

 which a little care and common sense might have avoided. 



THE CORONARY RING. 



The crust does not vary much in thickness (see a, page 295, and Z>, in the accom- 

 panying cut), until near the top, at the coronet, or union of the horn of the foot with 

 the skin of the pasterns, where (w, page 272), it rapidly gets 

 thin. It is in a manner scooped and hollowed out. It likewise 

 changes its colour and consistence, and seems almost like a con- 

 tinuation of the skin, but easily separable from it by maceration 

 or disease. This thin part is called the coronary ring, x, p. 272. 

 It extends round the upper portion of the hoofs, and receives, 

 within it, or covers, a thickened and bulbous prolongation of tha 

 skin, called the coronary ligament (see 6, in the accompanying 

 cut). This prolongation of the skin it is nothing more is 

 thickly supplied with blood-vessels. It is almost a mesh of 

 blood-vessels connected together by fibrous texture, and many 

 of them are employed in secreting or forming the crust or wall 

 of the foot. Nature has enabled the sensible laminae of the coffin-bone, c, which will 

 be presently described, to secrete a certain quantity of horn, in order to afford an 

 immediate defence for itself when the crust is wounded or taken away. Of this there 

 is proof when in sand-crack or quittor it is necessary to remove a portion of the crust. 

 A pellicle of horn, or of firm hard substance resembling it, soon covers the wound ; 

 but the crust is principally formed from this coronary ligament. Hence it is, that in 

 sand-crack, quittor, and other diseases in which strips of the crust are destroyed, it is 

 so long in being renewed, or growing down. It must proceed from the coronary 

 ligament, and so gradually creep down the foot with the natural growth or lengthen- 

 ing of the horn, of which, as in the human nail, a supply is slowly given to answei 

 to the wear and tear of the part. 



Below the coronary ligament is a thin strip of horny matter, which has been traced 

 to the frog, and has been supposed by some to be connected with the support 01 

 action of that body, but which is evidently intended to add to the security of the pan 

 on which it is found, and to bind together those various substances which are collected 

 at the coronet. It resembles, more than anything else, the strip of skin that surrounds 

 the root of the human nail, and which is placed there to strengthen the union of the 

 nail with the substance from which it proceeds. 



THE BARS. 



At the back part of the foot the wall of the hoof, instead of continuing round and 

 forming a circle, is suddenly bent in as in the small cut, in page 295, where d repre- 

 sents the base of the crust, and e its inflection or bending at the heel. The bars are, 

 in fact, a continuation of the crust, forming an acute angle, and meeting at a point at 

 the toe of the frog see a, b, and c, in the smaller cuts and the inside of the bars, 

 like the inside of the crust see the first and larger cut presents a continuance of the 

 horny leaves, showing that it is a part of the same substance, and helping to discharge 

 the same office. 



It needs only the slightest ' onsideration of the cut, or of the natural hoof, to sho\v 

 the importance of the bars. The arch which these form on either side, between the 

 frog and the quarters, is admirably contrived both to admit of, and to limit to its pro- 

 per extent, the expansion of the foot. When the foot is placed on the ground, and th 

 weiarht of the animal ; s thrown on the .eaves of which ^rnention has just been made* 



