72 THE HORSE. 



sary either to rlove-tail the materials into one another, or to pass strong iron 

 chains round them. For want of sufficient attention to this, " the dome of 

 St. Sophia in Constantinople, built in the time of the Emperor Justinian, 

 fell three times during* its erection ; and the dome of the cathedral of Flo- 

 rence stood unfinished an hundred and twenty years for want of an 

 architect." 



Nature, in the construction of the horse's head, has taken away the 

 pressure, or removed the probability of injury, by giving an additional layer 

 of bone, or a mass of muscle, where alone there was danger, and has dove- 

 tailed all the materials, and, to make assurance doubly sure, has placed this 

 effectual girder at the base, in the overlapping of the squamous portion of 

 the temporal bone. 



In the ox, where, to give a secure base to the horn, the frontal bone spreads 

 over the whole of the fore-part of the head, and the cranial cavity is suffi- 

 ciently secured by the beautiful mechanism between the two plates of that 

 bone, the temporal bone does not overlap the parietal. Nature gives 

 every thing essential to the protection and welfare of the animal, but nothing 

 superfluous. 



Above the j)arietalSy and separated from them by a suture (fig. g, pp. 66 

 and 68, and fig, c, p. 66), is the occipital bone. Superiorly it covers and 

 protects the smaller portion of the brain, the cerebellum ; and as it there 

 constitutes the summit or crest of the head^ and is not protected by mus- 

 cles, and particularly exposed to danger, it is interesting to see what thick- 

 ness it assumes. The head of the horse does not, like that of the human 

 being, ride upright on the neck, with all its weight supported by the spinal 

 column, and the only office of the muscles of the neck being to move the 

 head, forward, or backward, or horizontally on its pivot; but it hangs in a 

 slanting position from the extremity of the neck, and the neck itself projects 

 a considerable distance from the chest, and thus the whole weight of the 

 head and neck are suspended from the chest, and require very great power 

 to support them. In addition to the simple weight of the head and neck, 

 the neck projecting from the chest, and the head hanging from the extre- 

 mity of the neck, act with enormous mechanical force, and increase more 

 than a hmidred-fold the power necessary to support them. ■■ 



It requires a strong man to lift a small table from the ground at arm's 

 length. The farmer's steelyards shew that a weight of a few pounds, at the 

 extremity, will counterbalance or act with a force equal to a hundred weight 

 near the hook or centre. 



The head and neck of the horse, and particularly of some horses of a 

 coarse breed, are of no little bulk and weight. We shall hereafter have to 

 show in what breeds, and for what purposes a light or heavy head and 

 neck are advantageous; but it may be safely affirmed, that, projecting so 

 far from the chest, and being consequently at so great a distance from the 

 fulcrum or support, the lightest head will act or bear upon the joint be- 

 tween the last bone of the neck and the first rib, with a force equal to 

 many thousand pounds. 



How is this weight to be supported? Is the power of muscle equal to 

 the task ? The muscles of the animal frame can act for a certain time with 

 extraordinary force ; but as the exertion of this power is attended with 

 the consumj)tion of vital energy, the period soon arrives when their action 

 is remitted or altogether suspended. 



Muscular power is altogether inadequate to the constant support of the 

 head of the horse. A provision, however, is made for the purpose, simple 

 and complete. 



