M A M M A L 1 A. 



153 



perience tells them they can make by the exercise of 

 .their proper calling. 



This, however, is a question of political economy 

 rather than of natural history, although it is one very 

 closely connected with the usefulness of the mam- 

 malia in a state of domestication, and also with the 

 consideration as to which of them can be made the 

 most useful for domestic purposes. We shall not 

 enter upon t,he details ; but we may mention the 

 principle for the sake of those who may be fond of 

 turning their thoughts to such matters. It is a prin- 

 ciple easily stated : the mechanical substitute, what- 

 ever may be its name, its form, or the means by which 

 it is made to act, has no sagacity, it has merely the 

 capacity of doing so much mechanical labour, which 

 may he always reduced to a very simple standard, 

 namely, the raising of a given weight a certain num- 

 ber of feet in a given time. The animal again has 

 sagacity, and may be used to the full extent of this 

 sagacity, as well as to that of its mechanical strength. 

 Therefore, if no sagacity is required in the work to 

 be done, and the continuance and quantity of the 

 work are sufficient to cover the expense, the me- 

 chanical powers deserve the preference. On the 

 other hand, if sagacity is required, or if the work 

 is merely temporary, animal power is far better. 



In considering what animals ought to be used in 

 preference to others for assisting man in the perform- 

 ance of his labours, there are various considerations 

 to be made. There are only two ways of applying 

 animal power : the first is, by the weight of the ani- 

 mal acting at the end of a lever, or along the circum- 

 ference of a wheel, which is nothing more than a 

 succession of levers. An animal of some sagacity is 

 required for this purpose, because it must continue 

 going always in the same direction. The turn-spit 

 dog is an example of this kind, though one which it 

 is now rare to meet with in use. The dog attempts to 

 climb a series of steps in the inside of the ring of a 

 wheel ; and if the wheel is of a diameter properly 

 adjusted to his weight, his weight makes him descend 

 just as fast as he ascends ; and thus while he turns 

 the wheel he remains at the same relative point in 

 space, the wheel gliding away from under him as he 

 endeavours to advance. This is well, and also wit- 

 tily expressed by the poet : 



" a dog that turns a spit, 



Bestirs himself, and plies his feet 

 To mount the wheel, but all in vain 

 His own weight brings him down again." 



Dogs are almost the only animals which have suf- 

 ficient sagacity for being employed in this way ; but 

 they are not unfrequently employed to turn light 

 machinery, in cases where the work required to be 

 done is too limited for requiring a greater and more 

 expensive power. The tread-mill which is now used 

 as a species of hard labour for human delinquents, 

 acts upon the very same principle as the dog-wheel : 

 but the parties sent there are compelled to work, 

 from the injury that they would receive by the wheel 

 ft if they did not get upon the steps. 



The second mode of applying the power of animals 

 to useful purposes is that which takes advantage of 

 their powers of locomotion, and considers the resist- 

 ance which they can overcome when moving at a 

 certain rate without injury to themselves, though the 

 la*t consideration is sometimes neglected in a manner 

 disgraceful to the feelings, and not very conducive to 

 the pecuniary interests of the parties. This, though 



to a considerable extent it involves the structure of 

 the animal, and the form of its organs of locomotion 

 is, in the details, a matter of practical mechanics, 

 having little to do with the natural history of animals, 

 and not a very great deal with the mechanics of 

 their structures ; for it forms no part of the study of 

 the animal in a state of free nature, but is merely an 

 application by man of the power of the domesticated 

 animal. 



Moving a load or quantity of matter from one 

 place to another, either by carrying it, or by pulling 

 it, are the chief forms of this mode of applying animal 

 power, and as it is the only one in which the power 

 of animals is at all extensively employed, it is the one 

 which deserves the chief attention. 



In this respect there are necessarily a great many 

 differences, arising from the nature of the work which 

 the animal has to perform, and the character of the 

 ground over which it has to move ; and much of the 

 decision in this case must necessarily depend upon 

 the structure of the animal's feet. The feet of work- 

 ing animals are of two kinds, feet with toes and feet 

 with hoofs, and the latter are either single, or consist 

 of two real ones, on which the animal walks. In 

 addition to these it is necessary to include the ele- 

 phants and the camels, whose feet are not, strictly 

 speaking, of either class. The feet of the camel are 

 adapted for travelling over dry and sandy surfaces, 

 and those of the elephant suit better with soft ground 

 which is covered with rank herbage. The feet of the 

 camel have only two toes, furnished with nails rather 

 than with hoofs, which are united on the under side, 

 and the sole of the foot is covered with a soft pad, 

 which is equally ill -adapted for hard or stony sub- 

 stances and for humid ones. Accustomed to traverse 

 the sandy deserts, in quest of the hard and scanty 

 vegetation upon which it subsists, the camel lifts its 

 feet straight up, in order to clear the sand. Its march 

 is thus exceedingly dodging, and camel-riding is no 

 very agreeable exercise for those who are unaccus- 

 tomed to it. It is this high lifting of the feet, and con- 

 sequent planting of them down with the weight of the 

 body ramming them against the ground, w hich dis- 

 qualify the camel for walking with ease on the sur- 

 faces which we have mentioned. This jars the leg, 

 shakes the body, and pains the sole of the foot when 

 on a hard pavement ; and it is painful to look at a 

 camel when led through the streets of one of our 

 towns, where it has to tread upon unyielding granite. 

 This is most remarkably the case with the dromedary 

 or single humped camel, which is more feeble than 

 the one with the two humps, and also lifts its feet 

 proportionally higher. The same circumstances which 

 enable the two humped or Bactrian camel to travel 

 more easily over hard surfaces than the dromedary 

 enable it to do so over humid surfaces, and thus it is 

 useful over a greater range of country than the other. 



Still camels are useful only as beasts of burden, 

 and for long marches they are expensive animals. 

 Their pace, besides its jolting character already de- 

 scribed, is but slow, and the pain with which they 

 walk over hard surfaces, renders them of no use 

 whatever for draught. They are in fact fit only for 

 countries which are in great part deserts ; and in 

 proportion as mankind inhabit more closely together, 

 and have more of the accommodations of civilised 

 life, camels become less and less useful to them. 



Elephants are animals of great strength, and capable 

 of supporting, and occasionally of drawing, very heavy 



