100 THE HORSE. 



upward. Something more, however, is accomplished by this singular me- 

 chanism. The eye is naturally deep in the orbit, that it may be more per- 

 fectly defended ; but it may be necessary, occasionally, to bring the eye 

 forward, and enlarge the field of vision. The eye is actually protruded 

 under the influence of fear: not only are the lids opened more widely, but 

 the eye is brought more forward. How can this possibly be accomplished? 

 There are no muscles anterior to, or before the eye — there is no place for 

 their insertion. The object is readily effected by this singular pulley, 6, c. 

 By the power of this muscle, the trochlearis or pulley-muscle, and the 

 straight muscles at the same time not opposing it, or only regulating the 

 direction of the eye, it is really brought somewhat forward. The lower 

 oblique muscle rises just within the lacrymal bone (i, p. 66), and, proceed- 

 ing across the eye, is fixed into the part of the sclerotica, opposite to 

 the other oblique muscle, and it turns the eye in an opposite direction, 

 assisting, however, the upjper oblique, in bringing the eye forward from its 

 socket. 



Chapter VII. 



INJURIES AND DISEASES OF THE SKULL— THE BRAIN—THE EARS— 



AND THE EYES. 



We have now arrived at a convenient resting-place in our somewhat dry, 

 but necessary description of the structure of the horse, and we willingly 

 turn to more practical matter. We will consider the injuries and diseases 

 of the parts we have surveyed. In entering, however, on this division of 

 our work, we would premise, that it is impossible for us to give the farmer 

 such an account of the nature and treatment of the diseases of horses as will 

 enable him with safety to practise for himself, except in the commonest cases. 

 The causes of most diseases are so obscure, their symptoms so variable, 

 and their connexion with other maladies so complicated and mysterious, 

 that a life devoted to professional study will alone qualify a man to become 

 a judicious and successful practitioner on the diseases of the horse, and 

 other domestic animals. Our object will be to communicate sufficient in- 

 struction to the farmer, to enable him to act with promptness and judgment 

 when he cannot obtain professional assistance — to qualify him to form a 

 satisfactory opinion of the skill of the veterinary surgeon whom he may 

 employ, and, more especially, to divest him of those strange and absurd 

 prejudices which, in a variety of cases, not only produce and prolong 

 disease, but bring it to a fatal termination. 



FRACTURE. 



We have described the cavity of the skull of the horse as being so de- 

 fended by the hardness of the parietal bones, and those bones as so covered 

 by a mass of muscle, and protected above by an additional layer of bone, 

 and the occipital bone as so exceedingly thick (see cut, p. 68), that a frac- 

 ture of the bones of the skull is almost impossible. It can only occur 

 from brutal violence, except that, when a horse falls in the act of rearing, 

 the occipital bone is sometimes fractured ; when he falls forward, and 

 the head comes in contact with the ground, the muzzle or jaws will receive 

 the principal or whole force of the blow. When, however, fracture of the 

 skull does occur, it is almost invariably fatal. A blow of sufficient violence 



