PHYSICS. hives, or flying early abroad, to furnish themselves with wax, or honey; or, by their unexpected return before a ftorm: becaufe I fufpect that thefe things are not fo much the effects of inftinct, as of a tenderness, and quicknefs of fenfe; something analogous whereto may be seen in a good weather-glafs, and is alfo to be found in many wounded and valetudinary perfons, who are affected with fuch beginning alterations in the air, as other men perceive not. But among the peculiarities to be obferv'd in the conduct of bees, 'tis very remarkable, that, after a fight, they take up the dead which lay on the ground, and, as I have obferv'd, Ay away with them far from their hive.

Another obvious inftance of the instinct that nature has given to fome defpicable infects, may be taken from ants: for 'tis known, that these little creatures do, in the fummer, hoard up grains of corn against the winter. And their fagacity is the more confiderable, if it be true what many learned men affirm, that they eat off the germen of the grains they lay up, left the moisture of the earth, exposed to the rains, fhould make them fprout. But whatever become of this tradition, thefe infects perform fome other actions greatly resembling thofe proceeding from fagacity and industry.

The natural skill of fpiders in weaving their webs, that are fo fitly contrived, both to catch their prey, and give them immediate notice of its being caught, is a thing, which, if it were not familiar, would be look'd upon as admirable. And this skill is not, as fome imagine, an effect of imitating their parents; for if the eggs be taken away, and enclosed in a glafs, when they come to be hatch'd by the heat of the fun, the little creatures will immediately fall to fpinning in the glass itself, as was related to me by an eminent mathematician, who made the experiment. And I faw the lefs reason to diftruft it, becaufe having, by an external heat, hatch'd many eggs of filk-worms, in a place where there had not been any of a long time before, nor probably ever, till then; yet the worms produced by these eggs did in autumn, of their own accord, climb up to fuch convenient places as I had prepared for them, and there weave those curious oval prifons wherein they enclose themselves, and which are unravell❜d into extremely fine filk.

But this provident induftry is not confined to infects, for 'tis to be found in many of the greater animals, particularly in the beaver; a creature whereof, indeed, many fabulous ftories are related: yet fober and judicious perfons, who were either born, or lived in New-England, where thefe animals abound, have affured me, that the beavers, with their fharp teeth, cut pieces of wood, and fit them to their purpose; that, by joining their labours, they lay thefe together, fo as to build themselves frong winter-houses; in which there is fometimes a kind of fecond ftory for the inhabitants to retire to, when the water chances to overflow; that, for these houses, they chufe a very convenient fituation, just by fome river, or other water, that can furnish them with fish ; and that the hole belonging to each houfe is placed juft by the water, that

they may immediately flounce into it, and fo fave themfelves, when their PHYSICS. houses are attack'd. And, to facilitate their swimming, and the catching of their prey in the water, nature has given them two feet, not made like thofe of dogs or cats, or in the manner of their other two, but furnish'd with broad membranes betwixt their toes, like the feet of geese, ducks, and other aquatic animals, that are to use them as oars, to thruft away the water, and facilitate their motions.

The various arts employ'd by animals of different kinds, about the materials, the conftruction, and the fituation of their nests, is usually remarkable, and fometimes wonderful. Of this skill we have many eminent inftances, but 'tis particularly remarkable, that in countries abounding with apes and monkeys, creatures very greedy of birds eggs, there is a fort of bird whofe eggs they peculiarly affect, that hang their nests near the end of some long flexible branches which reach over the water, and by that means avoid their enemies, who cannot swim.

In the nests of wafps, which they often, for greater fecurity, make under ground, I have obferv'd a very curious and artificial structure, to conceal and fhelter their young ones till they are ready to fly.

But the inftinct that nature has planted in animals for their own prefervation, is much inferior to that providence she has furnished them with for the propagation of their fpecies.

There are many remarkable things to be met with in the nefts of feveral birds, both as to the materials, the ftructure, and the fituation of the places wherein they are built. I have feen nefts, and particularly fome made in the Indies, which would rarfe a man's wonder how the birds fhould find fuch odd, but commodious materials to build with. There are birds in the east, which make their nests of a white fubftance, that looks almost like ifing-glafs, diffoluble in liquors, and fo very well tafted, that it makes the chief fauce ufed in the fouthern parts of India. The ftructure alfo of the nests of feveral birds, both as to their figure, magnitude, and accommodations, wherewith they are furnish'd, for warmth and foftness, may deferve the applaufe of mathematicians, efpecially if it be confider'd that thefe little untaught architects had no tools to make their curious buildings with, except their bills and feet. Much more fore-fight, however, appears in the fituation of the place, that fome birds make choice of to build their nefts in; as may be obferv'd, not only in the pendulous nefts of swallows, and the fecret ones of fome European birds; but very confpicuously in the hanging nefts that we lately mention'd, to be fo oddly placed by fome birds, to fecure their eggs from apes and monkeys; and by the fituation of the nefts ufed for fauce as we just now related, to be found only upon high and steep rocks; which are fo faften'd to the concave parts of them, that look downwards, and commonly hang directly over the fea; that there is no getting them, without much trouble and danger: upon which account, as well as that of their delicacy, they are very dear, even in the East-Indies, where they are found.

The

PHYSICS. The like care to contrive their nefts advantageously, and make them in fecure places, is vifible in infects; as may be obferv'd in the fubterraneal nefts of the wafps, formerly mention'd, and in the eggs of fnails, which I have fometimes found hid under-ground; and have hatch'd in glaffes furnished with the fame earth wherein they were found.

If I fhould here fet to view the feveral effects and arguments of the wonderful providence, that the moft wife author of nature exercises about the propagation of animals, by diftinguishing them into male and female; by furnishing both fexes with mutual appetites and organs exquifitely adapted to the increase of their kind; by the admirable formation of the foetus in the womb, without the female's knowing how it is perform'd by the strange fubtilties and courage, that feveral creatures, either oviparous or viviparous, have, to hide and defend their young; by the full provifion that is made for the nourishment of the foetus, and the wel fare of the female after fhe has brought forth, and the like: I might much enrich and adorn my argument. But inftead of pursuing a fpeculation, that would lead me too far, I fhall look back upon the intimation I lately gave, that even thofe meaner parts of animals, which feem to have been framed with the leaft care and contrivance, are yet worthy of their author. For tho' the teeth be fome of the leaft elaborate parts of the human body, yet even thefe afford numerous phenomena applicable to our prefent pur. pofe but I fhall only tranfiently confider a few of them.

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And firft, 'tis remarkable, that tho' when a man comes to his full ftature, all the other bones of the body ceafe to grow, the teeth continue to increafe, in length, during his whole life. This growth of the teeth appears not only by their continuing for many years of the fame length, but by the unfightly fhooting of one tooth, when that which was oppofite to it in the other jaw is wanting; whence it has liberty to fprout without oppofition. Of this difference in point of growth betwixt the teeth and other bones of the body, what reafon can be fo properly affign'd, as its being intended to repair the daily waste of fubftance, proceeding from the frequent attritions of the upper and lower jaw in maftication?

2. Tho' the bones of the body are generally invefted with a very thin fenfible membrane call'd Periosteum that part of each tooth, which is not cover'd by the gums, wants it; which would be fubject to very frequent and painful compreffions and lacerations.

3. To enable the teeth to break and make comminutions of the more folid kind of aliment, nature has providentially framed them of a clofer and harder fubftance than almost any other bones in the body; tho' these are so numerous, that anatomifts reckon above three hundred of them. And I have met with it in authors of good credit, that fome mens teeth have been fo hard, as, when ftruck against another fit, body, to produce fparks of fire.

4. That these bones, whofe ufe is fo great, may themselves be continually nourish'd and fupplied; tho' they are fet in bone, the wife author of things has admirably contriv'd a cavity on each fide of the jaw-bone,

wherein are lodg'd an artery, a vein, and a nerve; which, thro' leffer ca- PHYSICS. vities, fend their twigs to each particular tooth.

5. As infants are defign'd by nature to feed for a confiderable time on milk, they remain long without teeth; whilft feveral animals, which are often early reduced to feek aliment that is neither fluid nor foft, come into the world with teeth already form'd in their jaws.

6. The bony fubftance appointed for the comminution of the aliment, ought not, for feveral reasons, to be in either jaw entire, or all of one piece; and therefore nature has providently made for that ufe a competent number of diftinct bones in either jaw. And because men may have occafion to feed often upon very different forts of aliment, and because ufually the fame aliment may require different preparations in the mouth, to facilitate the digeftion of it in the ftomach; nature has provided men with two rows of teeth, for the most part equal in number, and correfponding to each other, yet of different fhapes, for different ufes; the fore-teeth are broader, and have a kind of edge, to cut the more yielding fort of aliment, whence they are call'd Incifores; others being stronger, and more fitly shaped to tear the tougher food, are term'd Canini; there is also a third fort, whofe principal office it is to grind the aliment cut or torn by the others: and for this purpose they are made much broader, and fomewhat flattish, with their upper furfaces uneven and rugged, that by their knobs and little cavities they may the better retain, grind, comminute, and mix the aliment; and for this reason they are call'd Molares.

7. And because the operations to be perform'd by the teeth often require a confiderable firmness and ftrength, partly in the teeth themselves, and partly in the inftruments that move the jaw, wherein the lower fett of them is fix'd; nature has provided the lower, or moveable jaw, with strong mufcles, that it may bear forcibly against the upper; and has not only placed each tooth in a distinct cavity of the jaw-bone, as it were in a close, ftrong, and deep focket; but furnish'd the feveral forts of teeth with holdfafts fuitable to the stress, that by reason of their different offices is to be laid on them. And therefore the Incifores and Canini have ufually but one root, whilft the Molares, that on many occafions are employ'd to break hard bodies before they can be ground, are furnished with three roots, and often with four, in the upper jaw, whofe fubftance is somewhat fofter, and whofe grinders ferve as fo many little anvils for those of the lower to ftrike or press against.

If it fhall be faid, that allowing tho' man is indeed advantageously furnish'd with teeth, yet there are many other animals, fome whereof have not near fo many teeth, nor fo commodiously shaped and placed as his; others, that are not furnish'd with any teeth at all; and that feveral animals have some of their other parts lefs convenient in their kind, or are not otherwise near fo well provided for as they would be, if they were not rather the productions of chance, than of an intelligent and defigning agent: I muft declare, that many particulars might be farther alledg'd, to shew the final causes of things corporeal, as the confideration of them leads

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PHYSICS. to a high veneration of their divine author; and to manifeft, that when his providence is deny'd or condemn'd, 'tis for want of due confideration. But I have already, in great measure, prevented myself in the answering this objection, by obviating fome exceptions relating to the eyes of man and other animals. For the confiderations that have been alledg'd to that purpose, may, mutatis mutandis, be applied to the varieties to be found in the teeth, and other parts, of different kinds of creatures.

'Tis known, that oxen, fheep, &c. are not furnish'd with near fo many teeth as men, horfes, dogs, &c. But this defect, if it be any, is fupplied partly by the power and inftinct they have to chew the cud, and thereby make a fecond attrition of the aliment, that is already greatly soften'd; and partly by the fucceffive cavities, or ftomachs, thro' which that aliment is tranfmitted, and by that means elaborated and fitted for further ufes. The beaver, the tortoife, the bee, and the humming-bird, which fucks the exudations of flowers with his little long bill, like the bee, and many other animals, have their mouths, and their ways of preparing their aliment for the ftomach, very different from what is obferv'd in men; and yet each respectively very convenient; all circumftances confider'd.

These, and the like expedients, are in many animals fuch as afford no cause of taxing the author of nature, for not having given fome of them all the fame parts wherewith others are furnish'd; but rather, the providence and wisdom of God, in the contrivance of his visible works, may be as well discover'd by the feeming omiffion of this or that part, ufeful to other animals, but unneceffary to thofe wherein it is not found; as by granting those parts to fuch animals, whofe compleatnefs or welfare they are neceffary or highly conducive to and therefore 'tis not strange, that he has not given to men, and many forts of birds, fuch tough, transparent, and moveable membranes, as frogs are provided with, to defend their eyes from fuch accidents as the others are not ufually exposed to.

Bats are esteem'd a contemptible fort of creature, yet they may afford us a confiderable argument to our prefent purpose. For we have here an animal that flies like a bird, tho' it wants feathers, and has a fabric quite different from that of birds. And here too, we may obferve the compenfation that is made for parts that feem either deficient, or lefs advantageous, than thofe of the fame denomination in other birds; as alfo the regard which the divine artift appears to have to the fymmetry of parts in his animated works, and to their fitnefs to the places they are to frequent. For the bat being to act sometimes like a bird, and on fome occafions like a terrestrial animal, or mouse, he ought to be furnish'd with parts fuitable to fuch different defigns: and, therefore, the want of feathers in his wings is fupplied with a broad membranous expanfion, and a kind of toes furnish'd with articulations. And because this animal was to forbear fettling on the ground, otherwife than his occafions required, each of his wings is furnish'd with a ftrong crook, like the claw of a bird's foot; by the help of which, he can faften to trees, walls, &c. and there keep himfelf at what distance he pleases from the ground. And as he is furnifh'd