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therefore, whatever that cause was, has been concerned in the origin; has governed the production of these different animal forms.

When we pafs on to smaller animals, or to the inhabitants of a different element, the resemblance becomes more diftant and more obfcure, but ftill the plan accompanies

us.

And what we can never enough commend, and which it is our business at present to exemplify, the plan is attended through all its varieties and deflections, by fubferviences to special occafions and utilities.

I. The covering of different animals (though, whether I am correct in claffing this under their anatomy, I don't know) is the first thing which presents itself to our obfervation; and is, in truth, both for its variety, and its fuitableness to their several natures, as much to be admired as any part of their structure. We have bristles, hair, wool, furs, feathers, quills, prickles, scales; yet in this diversity both of material and form, we cannot change one animal's coat for another, without evidently changing it for the worfe: taking care however to remark, that these coverings are, in

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many cafes, armour as well as clothing;

tended for protection as well as warmth.

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The human animal is the only one which is naked, and the only one which can clothe itself. This is one of the properties which renders him an animal of all climates, and of all feafons. He can adapt the warmth or lightness of his covering to the temperature of his habitation. Had he been born with a fleece upon his back, although he might have been comforted by its warmth in high latitudes, it would have oppreffed him by its weight and heat, as the fpecies fpread towards the equator.

What art, however, does for men, nature, has, in many inftances, done for those animals which are incapable of art. Their clothing, of its own accord, changes with their neceffities. This is particularly the case with that large tribe of quadrupeds which are covered with furs. Every dealer in harefkins, and rabbit-fkins, knows how much the fur is thickened by the approach of winter. It seems to be a part of the fame conftitution and the fame defign, that wool, in hot countries, degenerates, as it is called, but in truth (most happily for the animal's ease) paffes into hair;

whilft, on the contrary, that hair, in the dogs. of the polar regions, is turned into wool, or fomething very like it. To which may be referred, what naturalifts have remarked, that bears, wolves, foxes, hares, which do not take the water, have the fur much thicker on the back than the belly: whereas in the beaver it is the thickest upon the belly; as are the feathers in water fowl. We know the final cause of all this; and we know no other.

The covering of birds cannot escape the most vulgar observation. Its lightness, its smoothness, its warmth; the difpofition of the feathers all inclined backward, the down about their ftem, the overlapping of their tips, their different configuration in different parts, not to mention the variety of their colours, constitute a vestment for the body, fo beautiful, and fo appropriate to the life which the animal is to lead, as that, I think, we should have had no conception of any thing equally perfect, if we had never feen it, or can now imagine any thing more fo. Let us fuppofe (what is poffible only in fuppofition) a person who had never feen a bird, to be prefented with a plucked pheasant, and bid to fet his wits to work, how to contrive for it a covering which shall unite

the qualities of warmth, levity, and least refiftance to the air, and the highest degree of each; giving it also as much of beauty and ornament as he could afford. He is the person to behold the work of the Deity, in this part of his creation, with the fentiments which are due to it.

The commendation, which the general afpect of the feathered world seldom fails of exciting, will be increased by further examination. It is one of those cases in which the philofopher has more to admire, than the common. observer. Every feather is a mechanical wonder. If we look at the quill, we find properties not eafily brought together, ftrength and lightness. I know few things more remarkable, than the ftrength and lightness of the very pen, with which I am writing, If we caft our eye to the upper part of the stem, we see a material, made for the purpose, ufed in no other clafs of animals, and in no other part of birds; tough, light, pliant, elaftic. The pith, also, which feeds the feather, is, amongst animal fubftances, fui generis; neither bone, flesh, membrane, nor tendon.

But the artificial part of a feather is the beard, or, as it is fometimes I believe called, the vane. By the beards are meant, what

are faftened on each fide the ftem, and what conftitute the breadth of the feather; what we usually strip off, from one fide or both, when we make a pen. The feparate pieces, or laminæ, of which the beard is compofed, are called threads, fometimes filaments, or rays, Now the first thing which an attentive observer will remark is, how much ftronger the beard of the feather fhews itself to be, when preffed in a direction perpendicular to its plane, than when rubbed, either up or down, in the line of the ftem; and he will foon discover the ftructure which occafions this difference, viz. that the lamina whereof these beards are compofed, are flat, and placed with their flat fides towards each other; by which means, whilft they easily bend for the approaching of each other, as any one may perceive by drawing his finger ever so lightly upwards, they are much harder to bend out of their plane, which is the direction in which they have to encounter the impulfe and preffure of the air; and in which their strength is wanted, and put to the trial.

This is one particularity in the structure of a feather: a fecond is still more extraordinary. Whoever examines a feather, cannot help

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