tions of the indefatigable De Luc will better ex- | ted from fresh water. All the known specimens plain our ideas. We have selected one from of the bones of viviparous land quadrupeds have either been found in these formations from fresh water, or in the alluvial formations; whence there is every reason to conclude that these animals have only begun to exist, or at least to leave their remains in the strata of our earth since that retreat of the sea which was next before its last irruption. It has also been clearly ascertained, from an atten tive consideration of the relation of the different remains with the strata in which they have been discovered, that oviparous quadrupeds are found in much older strata than those of the viviparous class. Some of the former have been observed in and even beneath the chalk. Dry land and fresh waters must therefore have existed before the foundation of the chalk strata. No bones of mammiferous quadrupeds are to be found till we come to the newer formations, which lie over the coarse limestone strata incumbent on the chalk. Deter minate order may also be observed in the succes sion of these. The genera which are now unknown are the lowest in position: unknown species of known genera are next in succession: and lastly, the bones of species, apparently the same with those which are now in existence, are never found but in the latest alluvial depositions.

among many instances which are afforded by an attentive examination of numerous coasts. 'Slapton Lee occupies the lower part of a combe, which at first formed a recess in the bay, but the sea before it being shallow, the waves brought up the gravel from the bottom along the coast, and the beach thus produced passed at length quite across this recess, which it closed: since then, the fresh water proceeding from the combe has almost entirely displaced the salt water within this space, because the former arriving there freely, and passing through the gravel of the beach, repels the small quantity of the sea water which filtrates into it. Slapton Lee, which is about two miles in length and a quarter of a mile in its greatest breadth, is a little brackish, on account of its communications with the sea water as well through the gravel in common seasons, as when there is any opening in the beach; however, it contains fresh water fish, carp, tench, and pike. The sediments of the land waters are tending to fill up this basin, and wherever the bottom is sufficiently raised the reeds are beginning to grow.'

Such may have been the process which formed a fresh water deposit upon a marine basis. By extending the analogy further, we can have little difficulty in conceiving that the barrier thus raised by the action of the waves may have been easily destroyed again, even by an extraordinary exertion of the same power which raised it, or by some other of those violent revolutions whose effects are marked upon the face of the whole earth. Thus a way was opened for the return of the waters of the ocean which again deposited their sediments, and the remains of their living tribes, and thus gave rise to the upper salt water strata. The same causes again acting, excluded once more the waves of the sea, and gave time for the deposit of the upper fresh water formation. Such an explanation appears to us simple and satisfactory. It accounts for the phenomena of nature by nature's laws. But, however this may be, the sagacity which first pointed out the distinction cannot be too much praised. The discovery has already stimulated the exertions of others, and there is reason to suppose that the phenomenon is not only not confined to the environs of Paris, but is of pretty general occurrence in secondary countries. A similar formation has been observed in the Isle of Wight; and has been most scientifically described and compared with the French strata.

The more we learn respecting the secondary strata of the globe, the more interesting becomes the investigation. The bold outline of the primi tive ranges, their cloud-capt summits and majestic forms, are calculated to rivet the attention; but they rather force the fancy to speculate upon their formation than lead the judgment by internal evidences to their origin. It is in the curious obser vations above recited that we seen to approach the history of our own state. The study of secondary formations is as yet scarcely commenced. The labors of Cuvier have thrown a new light upon their high importance; already by his exertions has the history of the most recent changes been ascertained, in one particular spot, as far as the chalk formation. This, which has hitherto been conceived to be of very modern origin, is shown to have owed its deposition to causes connected with the revolution and catastrophe before the last general irruption of the waters over our present habitable world. Our author well observes that these posterior geological facts, which have hitherto been neglected by geologists, furnish the only clue by which we may hope, in some measure, to dispel the darkness of the preceding times. would certainly be exceedingly satisfactory to have It is remarkable that those coarse limestone the fossil organic productions arranged in chrone strata which are chiefly employed at Paris for logical order, in the same manner as we now have building, are the last formed series which indicate the principal mineral substances. By this the a long and quiet continuance of the water of the science of organization itself would be improved; sea above the surface of the continent. About the developement of animal life; the succession of them indeed there are found formations containing its forms; the precise determinations of those abundance of shells and other productions of the which have been first called into existence, the sea, but these consist of alluvial materials, sand, simultaneous production of certain species and marl, sand-stone, or clay, which rather indicate their gradual extinction; all these would perhaps transportations that have taken place with some instruct us fully as much in the essence of organ degree of violence, than strata formed by quiet ization as all the experiments that we shall ever be depositions; and, where some regular rocky strata able to make upon living animals; and man, to of inconsiderable extent and thickness appear whom only a short space of time is allotted uppe above or below these alluvial formations, they the earth, would have the glory of restoring the generally bear the marks of having been deposi-history of thousands of ages which preceded the

existence of the race, and of thousands of animals which never were contemporaneous with his species.'

RENNET. The gastric juice and contents of the stomach of a calf, used in turning milk to curds.

duced every time the new horn is formed. This annual reproduction constitutes, in many points of view, one of the most remarkable phenomena of animal physiology. It affords a most striking proof, 1st, of the power of the nutritive process, and of the rapid growth, which is dependant on this in warm-blooded animals. For the horn of a stag, which may weigh a quarter of an hundred, is completely formed in ten weeks. 2dly, Of a limited duration of life in a part of an animal, entirely in

RENTAL or RENTROLL. In England, a roll in which the rents of a manor are set down; the collective amount of rents from any man's estates.dependent on the life of the whole animal, which

REPELLANTS. Medicines which drive the humors from the part where they have settled.

REPETITION. In Rhetoric, a figure which gracefully and emphatically repeats either the same word, or the same sense in different words. In the use of this figure care is to be used that we run not into insipid tautologies, nor affect a trifling sound and chime of insignificant words. All turns and repetitions are so, that do not contribute to the strength and lustre of the discourse, or at least one of them. The nature and design of this figure is to make deep impressions on those we address. It expresses anger and indignation, full assurance of what we affirm, and a vehement concern for what we have espoused.

REPRISALS. The seizing the vessels or goods of merchant strangers, as an equivalent for some loss sustained from the nation of which they are subjects.

in the stag extends to about thirty years. 3dly, Of change of calibre in particular vessels. For the branches of the external carotid, which supply the horn, are surprisingly dilated during its growth; and recover their former area, when that process has ceased. 4thly, Of a peculiar sympathy, which is manifested between the growth of the horns, and the generative functions. For castration, or any essential injury of the organs of generation, impedes the growth, alters the form, or interrupts the renewal of the horns.

The cuticle of the snake is separated every year, and comes off as a complete sheath, excepting the aperture, through which the animal escapes: the covering of the cornea is shed with the rest of the external integument.

Crustaceous animals (the crab, lobster, &c.) have a skeleton, which surrounds and contains their soft parts, and which serves, at the same time, the purposes of a skin. When it has attained its perfect consistence, it grows no more; but, as the soft parts still increase, the shell separates, and is detached, being succeeded by a larger one. The calcareous bodies in the stomachs of these animals performing the office of teeth, are shed with the

REPRODUCTION. In Physiology, in speaking of the growth of organic bodies, we must notice their power of reproduction; that wonderful pro-shell. perty of restoring or renewing parts that have been The second, or extraordinary kind of reproducmutilated or entirely lost. This is one of the most tive power, is that by which wounds, fractures, or important provisions of nature, inasmuch as it any accidental mutilation or loss of parts of an guards animals and plants against the multiplied organized body are remedied or restored. This dangers to which their bodies are exposed. Hence, exists in very different degrees in different departwhen viewed in connexion with the system of nu-ments of the animal kingdom. In man, and such trition, altogether, it forms one of those decisive and grand characters, which distinguish at once the machines that proceed from the hand of the Creator, from all, even the most ingenious and boasted, productions of human skill. The difference is recognised at the first glance; the distance is immeasurable. The springs and wheels of mechanical instruments have no power of repairing themselves, when they are bent, broken, worn, or spoiled; but such a faculty is enjoyed in various degrees by every animal and by every plant.

At different periods of the year, several organized beings lose, by a spontaneous and natural process, certain parts of their bodies, which are subsequently renewed. Examples of this occur in the fall of the stag's horns; in the moulting of birds; in the renewal of the cuticle of serpents, and other amphibia, of the larvae of insects, and of the shell of the crustacea, the fall of the leaves of trees, &c. This may be called ordinary or natural reproduction. The stag's horn, or antler, as it should be more properly called, is a mass of true bone, possessing the structure and characters of osseous substances. In its early state it is soft, and traversed by large vessels, which must be repro

animals as are nearly allied to him, the property is very limited, although sufficiently active to be capable of remedying the effects of great injuries. If a bone be broken, a muscle or tendon divided, or a piece of skin destroyed, processes are set up in the parts by which restoration is accomplished. The ends of the bone are joined by an osseous substance, which gives to the part its original solidity; the tendon regains its firmness and power of resistance; the muscle can contract again and move the points of its attachment; and the surface of the body is covered by a new piece of integument. The functions of the parts are restored; but the newly formed matter can be always distinguished from the original composition of the body, and possesses a weaker vitality. For, in some cases, old ulcers have broken out afresh, and even fractures have been disunited in states of great general debility. A divided nerve is reunited, even if a small portion be removed: and the function of the part, suspended for a time, is thus restored. The case is different in the blood-vessels; the processes consequent on wounds of these tend to stop the hemorrhage, which in general can be effected only by the obliteration of the tube.

The power of repairing the effects of injury is modified by various circumstances. The health and strength of the individual, the age, the air, and other circumstances, which the surgeon must attend to, have great influence.

Upon this depend all the phenomena of very light glass bubbles floating on water, about which, when clean, the water rises; but when greased, the water sinks into a channel all around them. Hence also it is, that in a glass vessel of water, the fluid stands higher all about the edges near the glass than towards the middle; but when the glass is stands higher at the middle than at the sides. Hence, also, in a glass not full of water, a clean glass bubble always runs to the side, by reason of the pressure, which is upon it towards the middle, In the lower orders of the animal kingdom, on and is partly taken off by the attractive force with the contrary, such are the strength and perfection which the water is raised near the edge. If the of the reproductive energy, that considerable mem-glass be so full as to be ready to run over, the bubbers are formed again, and we can hardly assign a ble returns from the side towards the middle, the limit to the power in some instances. The lower force with which the water is raised in the middle we descend in the scale of beings, the more sur-taking off part of the pressure. prising are the manifestations of this reproductive faculty. It is familiarly known, that the claws of the crab and lobster, and the entire limbs or tail of the newt, can be restored: the same holds good of the rays of the star-fish, and the arms or tentacula of the cuttle-fish. It was asserted by Bonnet and Spallawsani, that the entire head of the snail can be reproduced; but the assertion was suspected, because other experimentalists did not succeed in repeating the trials. Hence Blumenbach was led to observe, that some experiments on this reproductive power require a hand exercised in such employments, together with various precautions, and a favorable combination of circumstances, for their success. Hence persons must be cautious in concluding against the truth of any statement, because their own experiments do not succeed.'

In the cases which have been just mentioned, the restorative power repairs injuries; but it goes no further. Neither in man, nor in any warm-filled till the water run down on all sides, then it blooded animals, are entire organs ever reproduced. If a limb be cut off, or a piece of flesh taken away, the wound is healed, the chasm is filled up; but the lost parts are never formed again.

The fresh water polype exhibits very surprising powers in this way. If it be cut into two or more pieces, these become perfect animals. If it be slit half way down, the two halves are rendered perfect, remaining united below: these may be slit again, with the same results. The opposite ends of two polypes may be made to grow together.

REPTILES. In Zoology, the class of creeping animals, or such as rest on one part of the body while they advance with the other. Most reptiles have feet, but very small ones, and legs remarkably short in proportion to the bulk of their bodies.

REPULSION, REPULSIO. In Physics, the act of a repelling power, by which bodies, under certain circumstances, naturally fly from each other. Repulsion is the counter part to attraction. Attraction only reaches to a little distance; where that terminates, there repulsion commences.

Thus, if a fat body, lighter than water, be laid on the surface of it, or if a piece of iron be laid on mercury, the surface of the fluid will be depressed about the bodies laid on it. This is a plain indication of repulsion; as the rising up of the fluid about the surfaces of other incumbent bodies is of attraction.

In the latter case, the fluid is suspended, by an attractive power, above the level, and kept from falling by its gravity: in the former, a depression is made by the repelling power, which the liquor, notwithstanding its gravity, cannot run down into, and fill up.

Just the reverse happens if the bubble be greasy; because there the force, by which the water and the bubble repel each other, is greatest where the water is highest. Two clean bubbles, and two greasy ones always run towards each other, as being attracted; and a greasy and a clean one always fly each other, as being repelled.

RESERVE. A body of men kept apart in the day of battle for some particular service, as occasion may require.

RESERVOIR. A place artificially constructed for the collection and retention of water, in order that it may be conveyed to distant places, by means of pipes.

RESIDUARY LEGATEE. He to whom the residue of a personal estate is given by will.

RESIN. From the various species of Pine, there exudes a balsam, which concretes in the form of tears. It differs somewhat according to the peculiar tree from which it is obtained, and by distillation it is separated into two distinct ingredients: oil of turpentine, which is volatile, and resin, which is not. If a quantity of pine wood is collected, covered with turf, and then set on fire, the resinous juice which would have been dissipated in the open air, may be collected in a suitable receptacle beneath. In this way, tar and pitch, two well known articles of commerce, and both of a resinous nature, are usually procured.

Some of the most common examples of resin, are Copal from a species of Sumach, Mastick from the Pistacca, a tree which grows in the island of Chios, and Sandarach from the common Juniper. From the Amyris Gileadensis, a shrub which grows in Palestine and Arabia, is obtained a resin long celebrated for its medical virtues. It is the Balm of Gilead, so frequently alluded to in sacred history, and it is still highly prized by the Turks, who prohibit its exportation.

On the epidermis of many vegetables, we find a soft bluish powder which may easily be removed. It is denominated the Bloom, and occurs on Plums, cabbage leaves, and several other plants, always resisting the action of water, but like the other resins readily soluble in alcohol.

No kind of wood is so durable as that in which

the resinous secretion abounds. It is rarely injured by those insects which devour the hardest timber, and the insolubility of resin most effectually secures it from the destroying agency of water. As a proof of this fact, it has been observed that the Cypress gates of Constantinople, erected by the Emperor Constantine, were found undecayed a thousand years after they were built. It is owing to this secretion that Pine is more durable than the hardest Oak, though at the same time it contains much less of the woody fibre, on which the value of timber usually depends.

animals? The results of all the investigations hitherto made, induce us to answer this question in the affirmative; but the point is not yet demonstrated in all cases.

The differences which animals exhibit in their mode of breathing, or in the manner of effecting the changes which their nutritive fluid undergoes from the action of the atmosphere, depend on other eircumstances in their organization. Vegetables, and animals which have no circulation, respire by their whole surface, or by means of vessels, which convey air to all points of their interior. Those only which have a true circulation breathe by a particular organ. The heart being in them a common point of departure and return for the blood, the vessels containing that fluid could easily be so arranged as to convey it to the lungs, after it had circulated through the body; this was obviously impracticable in instances, when the nutritive fluid is every where uniformly expanded, without being contained in vessels. Hence respiration by lungs or gills is a function dependant on that of circulation, and may be regarded as a remote consequence of those faculties which characterise animals.

RESPIRATION. In Physiology, that function of animal bodies, in which the air, either in its elastic state, as it constitutes the atmosphere, or held in solution in water, is brought into contact with some organ or organs, undergoing alterations in its own constitution, and producing changes in the nature of the animal fluids, which are essential to the continuance of life. In the mammalia, birds, and reptiles, the respiratory organs consist of lungs, that is, of membranous cavities, differently constructed in the three classes, but agreeing in the circumstance of alternately receiving and emitting a portion of atmospherical air. This alternate in- Respiration presents to our observation two very gress and egress of air constitutes properly what different kinds of phenomena: 1st, the motions of is called in common language breathing, to which the lungs, gills, or other instruments of breathing, the philosophical term respiration is synonymous. or of parts connected with them, by which the We extend the term to animals of the lower class- former are alternately dilated and contracted for es, which have no lungs, and some of which do not the admission and expulsion of the air, and the even breathe, that is, do not receive and emit air latter are exposed to a current of water; and 2dly, at all. In consequence of the medium in which the changes produced in the blood or other anifishes are immersed, they cannot take in the at-mal fluids, and in the air or water, in consequence mospheric air in its elastic state, and they conse- of their mutual exposure in these organs. The quently have an apparatus, altogether different first may be termed the mechanical, and the secfrom that which exists in the three classes already ond the chemical phenomena of respiration. named, for the purpose of producing analogous The functions of the respiratory organs are effects in their economy. They are furnished with closely connected with the other great processes a passage communicating with the fauces or so- of the animal economy. The heart, brain, and phagus, and terminating in the external surface of lungs, more particularly influence each other, and the body, through which a part of the water re-present, in their mutual relations, numerous and ceived into the mouth is forcibly propelled. In highly interesting considerations for the physiolo-' this passage, the branchia or gills are situated; and the blood, which circulates in their fringed extremities, is thus exposed to the action of a quan- REST. The continuance of a body in the same tity of air, which the water always holds in solu- place, or its continual application or contiguity to tion. Crustaceous animals, and many of the mo- the same parts of the ambient or contiguous bodies; leusca, have organs more or less similar in struc- and therefore is opposed to motion. Sir Isaac ture and functions to the gills of fishes. Insects, Newton defines true or absolute rest to be the conboth in their larva and perfect states, possess nu- tinuance of a body in the same part of absolute merous ramified tubes, distributed over their whole space; and relative rest to be the continuance of body, and provided with open mouths, which ad- a body in the same part of relative space. Thus, mit the passage to and fro of the external air. Al- in a ship under sail, relative rest is the continuance though the structure of organs in fishes and in- of a body in the same part of the ship; but absosects is so different from that which we find in lute rest is its continuance in the same part of unmammalia, birds, and reptiles, they perform an iversal space, in which the ship itself is contained. analogous office, answer the same general purposes It is one of the laws of nature, that matter is indifin the animal economy, and are considered equally ferent to motion or rest. in the light of organs of respiration; this term be- REST, in Poetry, is a short pause of the voice in ing employed now to denote the general effect pro-reading, being the same with the cæsura, which, in duced by these various organizations, without any Alexandrian verses, falls on the sixth syllable; but reference to the means through which it is produ- in verses of ten or eleven syllables, on the fourth. ced; although it was originally applied to the passage of the air to and from the lungs, when the results of that process where unknown.

Is respiration, considered in its most extensive sense, a function necessary to the existence of all

gist.

RESURRECTION. Signifies sometimes the restoration of Christ from the dead, and sometimes the expected renewal of the human body destroyed by death. The credibility of the resurrection of

Jesus Christ rests partly on the testimony of the apostles, and partly on this circumstance, that, without it, we cannot explain how the apostles, who saw their hopes disappointed by his death, and had lost their confidence in him, could have been inspired with a lively faith in his divine mission, and with a belief which gave them strength to preach the gospel amid danger and persecution. He who considers Christianity as a revelation, as an institution founded by the immediate act of God, cannot think it strange that it was established by miracles, and that Providence used extraordinary means to attain an extraordinay end. Of the resurrection of the body, men have often adopted the grossest ideas. In the notion itself, that Almighty Power can form, of the materials of the old body, dissolved by death, a new body, which may serve as an instrument in a new order of things, there is nothing opposed to reason.

most important; and is a manœuvre the most calculated to display the prudence, courage and address, of an officer who commands. The most famous retreat in ancient history was that of Xenophon.

REVELATION. The act of revealing or making known that which was previously secret. In theology, by revelation is understood a special discovery of certain truths, made by the Deity to man.

REVENUE, PUBLIC. The portion of the general income of a state, which is appropriated to the payment of national expenses. Different nations have adopted different modes of raising a public revenue, but the rent derived from land being obviously a fund of a more permanent naturė than most others, has usually been one of the earliest resources, and has sometimes been the principal source of public revenue, particularly in ancient times. From the produce or rent of the

RETARDATION. In Physics, the act of diminishing the velocity of a moving body. If bod-public lands, the republics of Greece and Italy ies of equal bulk, but of different densities, be derived, for a long time, the greater part of the moved through the same resisting medium, with revenue which defrayed the necessary expenses of equal velocity, the medium will act equally on each, the commonwealth; and the rent of the crownso that they will have equal resistances, but their lands constituted the greater part of the revenue motions will be unequally retarded, in proportion of the ancient sovereigns of Europe. The introto their densities. Retarded motion from gravity duction of a different mode of warfare, and the is peculiar to bodies projected upwards, and this in greater duration of modern wars, increased conthe same manner as a falling body is accelerated; siderably the public expenditure, and rendered it only in the latter, the force of gravity acts in the necessary to raise a much greater revenue. In the same direction with the motion of the body; and ancient republics of Greece and Italy, every citizen in the former in an opposite direction. As it is the was a soldier, who both prepared himself for sersame force which augments the motion in the fall-vice, and served at his own expense; and in the ing, and diminishes it in the rising body, a body ancient monarchies of Europe, the people, when will rise till it has lost all its motion; which it does in the same time wherein a body falling would have acquired a velocity equal to that wherewith the body was projected upwards.

RETE MUCOSUM. A mucous membrane between the epidermis and the cutis, which is one part of the integument of the skin.

RETICULA. A contrivance among astronomers for measuring the quantity of eclipses.

RETINA. The third or innermost membrane of the eye, expanded round the choroid coat, like a net, to the ciliary ligament. It is the true organ of vision, and is formed by an expansion of the pulp of the optic nerve.

they served in the field, were, by the condition of their feudal tenures, to be maintained either at their own expense or at that of their immediate lords, without bringing any new charge upon the sovereign. The other necessary expenses of government were very moderate. The administration of justice, instead of being a cause of expense, was a source of revenue. The labor of the country people, for three days before and after harvest, was thought a sufficient provision for maintaining all the bridges, highways, and other public works, which the commerce of the country was supposed to require.

In those days the principal expense of the sovereign seems to have consisted in the maintenance of his own family and household. The officers of his household, accordingly, were then the great officers of state. The lord treasurer received his RETORT. In Chemistry, is a kind of round-rents; the lord steward and lord chamberlain bellied vessel, made of earth, glass, or metal, having looked after the expenses of his family; the care a crooked neck or beak, to which the recipient is of his stables was committed to the lord constable fastened. Retorts are of essential service in distil- and the lord marshal; his houses were all built in lations, and most frequently for those which re- the form of castles, and the keepers of those houses quire a degree of heat superior to that of boiling or castles might be considered as a sort of military water. governors, who seem to have been the only military officers it was necessary to maintain in time of peace. In these circumstances, the rent of a considerable landed estate might, upon ordinary occasions, very well defray all the usual expenses of government, and whenever extraordinary circumstances caused a greater expense, the sum necessary to make it good was drawn from the people by some arbitrary and often very unequal imposition.

RETREAT. In a Military sense, an army or body of men are said to retreat when they turn their backs upon the enemy, or are retiring from the ground they occupied: hence every march in withdrawing from the enemy is called a retreat. That which is 'performed in sight of an active enemy, who pursues with a superior force, is the