38 FORM AND ACTION. 



As far as steady and stable support be the object, it will readily 

 be admitted that four legs are better than three, and that two "by 

 no means could be made to answer the purpose of four, or even 

 three : a three-legged form stands not so firmly as one with four 

 legs ; and though one with two legs may be contrived so as to 

 stand alone, yet the slightest force disturbs its centre of gravity, 

 and it falls ; so little power of balancing itself is it found to 

 possess. The three-legged table or stool, from its being circular 

 or triangular, will stand as firmly as though it had four supporters ; 

 but the square table or oblong form requires four legs, one at each 

 corner or salient angle, or two at either side, to give it the full and 

 firm support of which by the carpenter's art it proves to be sus- 

 ceptible. Six or eight legs would nothing augment the stability 

 or safety of the form, and but little its strength : every projecting 

 part has already its prop of support, and the intermediate parts, 

 unless the form be one of extraordinary length, require none. Thus 

 it is with the animal body. Its oblong formation demanded four 

 supporters, two before and two behind : three would not have 

 given it the stability and power of resistance it at present pos- 

 sesses ; and again, to have added two legs more, would have 

 nothing increased the security of the standing posture, and but 

 little the powers of support, while loco-motion must by such an 

 addition necessarily have become more or less complicated and 

 impeded. 



It is seldom that the horse, while at rest, employs all his legs 

 in maintaining the standing posture : commonly, one of the hind 

 limbs will be found flexed — in a state of relaxation and repose, 

 propping up the body passively only — while the other three re- 

 main extended : in this position, changing the flexed hind-leg from 

 time to time, a horse will not only take his rest, but will sleep ; no 

 vigil or attention of the will being required to keep him upon his 

 legs. Some horses never lie down — never appear to require re- 

 cumbent repose. 



Another reason why Nature has given four legs to the quad- 

 ruped, is, that he may be enabled in progression to steadily poise 

 himself upon three of them, while the fourth is in motion off the 

 ground. Not merely in the walk and trot, but even in the gallop, 

 is the action of the legs, both in leaving and coming to the ground, 



