the inert body be stimulated into activity? Many questions of this kind might be asked. It is not because this communication of motion by collision is free from difficulties, that it is thus placed in the first rank. It is because, while we can resolve other supposed causes of motion into this, we cannot resolve this into any other cause. The law of Economy obliges us therefore to select it. If we really cannot form any other conception of gravity than as the result of an attractive force, we must reconcile ourselves to this conception; and the general mind of Europe seems, indeed, to have adopted this attractive force as an article of scientific faith. But if the older and indisputable force or law of momentum be sufficient to explain the facts of gravitation, then let us adhere exclusively to it.

Without further preface, we will state the manner in which it is here proposed to liberate us from the conception (which until time, or repetition, had accustomed them to it, appeared to all men very extraordinary) of distant bodies having towards each other a power of attraction.

Let us imagine, says M. Saigey, an ether extending uniformly through space; its atoms, animated by movements of projection and translation, strike and rebound from each other in the manner we have already described. Suppose now that at a point in this medium there should be a special and permanent cause of disturbance-say a molecule in a state of vibrationthis disturbance will extend and propagate itself in every direction through the ether. The atoms nearest to the vibrating molecule will receive the most violent movement, their ranks will be broken and dispersed, and the stratum, or sphere, contiguous to the molecule will be less dense than the rest of the medium. The action of the molecule being continued, the same effect is propagated from circle to

circle, or from sphere to sphere, throughout space. As final result, the ether will be distributed about this centre of movement in concentric layers, of which those nearest the molecule will be least dense and the rest will increase in density as they retire from it.

This state of things is easily imagined. Now suppose that a second molecule finds itself at any point in such a system. It will encounter on the side of the first molecule, layers of ether less dense than on the opposite side. Struck by the ethereal atoms in every direction, it must nevertheless receive fewer shocks on the side towards the molecule. It must tend consequently to approach it.

Here we have our gravity. The second molecule is driven towards the first, because it encounters layers or circles of the ether of different densities, and the energy of this action will be found, by the mathematician, to be in inverse proportion to the square of the distance of the two molecules; answering to the known law of gravity.

What we have stated of two isolated molecules, will apply to molecules grouped in the manner to form a body. Such a group will produce this variety of density in the ether we have described, and produce it in a still greater degree, in proportion to the greater number of the molecules, or larger mass of the body. The planets are bodies of great volume urged towards the sun by the same condition of things as causes heavy substances to fall upon the earth. In both cases attraction is but that tendency to approach which is due to the external impulses of the surrounding ether.

It will be thus seen that we are justified in calling the ether imponderable, while we attribute weight to the molecular body, which, nevertheless, is but an aggregate of ethereal atoms. Weight is, in fact, the result of a relation

between matter in the two states. The aggregate we call a body finds itself in a medium of unequal density; these varieties of density are regulated by the strictest law, and indeed are produced by, and in proportion to, the molecules of bodies. In a medium so disposed, the body is subjected to a greater number of shocks on one side than on the other, and moves in obedience to the preponderating impulses.

Much, of course, remains to be done by the mathematician and the physicist to establish a theory of this description. We are far from expecting the reader to be at once satisfied with this account, which we have extracted as faithfully as possible from M. Saigey's work. We are not altogether satisfied with it ourselves. We should have several questions to put to M. Saigey. We think, however, that some such theory may be so far received as to be put fairly on its trial. Meanwhile it must be confessed that it promises to release us from a curious anomaly, this attractive force ascribed to matter. Momentum, or the communication of motion by one moving body to another, may, as we have already intimated, be only more familiar to the mind, not in itself less perplexing. But this familiar fact we cannot, by any possibility, disallow; and it would be at least a grand simplification if we could say of every motion that it was an instance of this fact,-if we could say that no motion takes place but by the contact of a moving body, which loses motion in proportion as it gives.

There is a point here which requires a word of explanation, and M. Saigey affords us the explanation in a very luminous manner.

Those who hesitated to admit the existence of an ether were in the habit of raising the objection, that if it really existed it ought to retard the revolution of the planets, that it ought to offer a resistance which astronomers had

not detected. plied that the resistance would be so feeble that it would escape the detection of the astronomer. Some have calculated that it would abridge the distance of the earth from the sun at the rate of three metres during every revolution of the earth, and thus shorten our year by one second in six thousand years. It will be readily admitted that our astronomical observations do not enable us to eliminate a result like this from amongst the numerous perturbations to which our terrestrial orbit is liable.

To this it was re

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But if the ether offered no appreciable resistance to the planets, it might to the comets. These once dreaded bodies, which were to strike the stars out of heaven, and envelop the earth in destruction, have been discovered to be of an extreme tenuity, such as it tasks the imagination to conceive. Buffon could call in the aid of a comet to explain the origin of our planetary system; a wandering mass of this description struck the sun, and detached from it huge fragments, which it launched into space. countryman of Buffon, M. Faye, has lately calculated that the nucleus of a comet-the part most solidis hardly nine times more dense than that residue of atmosphere which remains under the glass of an air-pump when we have done our utmost to make a vacuum. And as to the tail-as it is still profanely called - that is six billion times less dense than the nucleus. This extreme tenuity may well render the comets susceptible to the least resistance from the medium they traverse; but it renders them susceptible also to all imaginable or unimaginable incidents-say to a resistance from the smallest bodies, such as we call meteroic which they may encounter in space. We believe the diminution in the periodicity of Encke's comet is the only instance at present relied upon for the detection of the resistance of the ether through the movements

of these extraordinary bodies. But, as M. Saigey remarks, a conclusion drawn from a solitary example amidst the uncertainty which reigns on the conditions affecting cometary movements, cannot be regarded as bien rigoureuse.

Are we bound, however, under the new light of our theory of gravitation, to look for any such resistance whatever? Gravity, or that force which propels the earth towards the sun, is the result of the action, in every possible direction, of the ether on the planet; the planet moves in obedience to the more numerous impulses it receives in one direction than in any other. The effect, therefore, of the ether on the planet is altogether absorbed and accounted for when you have calculated the precise force of gravity.

Following a mathematical analysis, our astronomers assign two forces to the production of the circular movement of a planetan initial force of projection impelling it in a straight line, and a force of gravity which constantly inflects its course. This equilibrium, established by astronomers, independently of any notion of an ether, must be compromised, it is thought, by the introduction of this universal medium. But if we now recognise in the medium the origin of one, at least, of these forces, the character of the problem is altogether altered. In the equilibrium established by astronomers the whole effect of the ether had been already absorbed; it had been absorbed in that gravity, or centripetal force, which they had so accurately calculated. In saying that the ether produces exactly such force of gravity, we have taken account of the shocks or impulses it gives on all sides; we should make a double employment of some of them if, under the form

of resistance to movement, we introduced, a second time, those shocks which the planet receives on the path in which it moves.

The ether cannot be introduced first as a cause and then as a resistance of motion, when, in estimating it as a cause of motion, you necessarily took account of its impulse in every direction. This being so, it is not to be expected that astronomers will have any such resistance to detect. And, on the other hand, those who, on purely theoretical grounds, have concluded that there must be such resistance, and that therefore, sooner or later, the earth must fall into the sun, may dismiss their alarms.

Thus we have given an outline of what may be considered, in the present state of our knowledge, a bold theory of the material universe. An agitated ether fills all space. The ethereal atoms form, by their aggregation, molecules; these latter, by a second aggregation, form bodies. There is no attempt to explain the passage from the atom to the molecule, nor why it is that the molecule never resolves back again into its component atoms, or why it is that the aggregating process has ceased, and new molecules are not formed. But we may observe that a like difficulty arises on the passage from inorganic molecules to the cell, which is the unit of animal and vegetable life. No one doubts that the cell is composed of inorganic matter, yet it is received as an established fact that no cell is produced except from some previous cell. first passage from the inorganic to the organic is as obscure a matter as the first passage from ethereal atoms to the molecule. Between these atoms, these molecules, these bodies, take place exchanges of movement, which constitute for us light, heat, electricity, gravity, and chemical affinity. The conception of the physical universe rests entirely on these data. Force is a name given to that momentum which is measurable by mass and velocity. When matter seems roused, as it were, from sleep, and stirred into the exercise of its latent

So that the

power (as it has been called), what really takes place is but an exchange of movements which escape all cognisance of the senses-probably vibratory or rotatory movements of a constant character-into movements which affect our senses, and produce changes in the constitution of bodies. The permanency of any body is the constancy, or periodicity, of certain movements; the change in such body, or its destruction, is a change in such movements. The dull piece of black coal that lies, so far as our senses indicate, motionless before us, is supposed to be the arena of swift, concentrated, constant movements; these the ethereal atoms, or other matter, moving in the mode we call heat, will change into other movements; there will be coal no more; the particles will have broken up that rhythmic motion which essentially constituted its solid form, they will have dispersed and entered into new unions and new harmonies of motion.

As M. Saigey observes, we are at first tempted to give the celestial bodies, in their vast revolutions through space, the largest share of

force or movement in the universe. But the force represented in the movements of suns and planets is feeble, he thinks, compared to that which is concentrated in molecular action. And what if the movements of suns and planets, about which so many theories have been devised, should at last be studied in the movements of the molecule ? The movements of suns and systems may be but results or examples of those two movements of rotation and translation with which we found it necessary to endow every atom from the commencement.

Need we add that we have still to ask how atoms came to be endowed with these movements, and were brought into all these rhythms or harmonies? Need we add that our last and boldest generalisations only make the necessity more glaring, to supplement the atom and its movement with the great idea of Intelligential Power?

"God, and the atom, and the soul of man, Something we seem to know of all the three,

Something and only-always-of the Three!"

SWEETER than sunshine dispersing storm is the peace that extinguishes an old inveterate quarrel, when that peace is so profound and perfect that the combatants can talk over all the shapes and incidents of their old warfare without the risk of fresh outbreak or even of irritation. This is notably the position of the old dispute between England and Scotland on the great supremacy question. The annals of human strife record no contest so bitter or enduring. We speak of the Seven Years' War, and the Thirty Years' War. Sismondi has given to the Plantagenet aggression in France the name of the Hundred Years' War. The struggle in Britain, on the one side for supremacy, on the other for independent selfgovernment, is as well entitled to the name of the Three Hundred Years' War.

Throughout the later portion of this mighty struggle-say from Bruce's victory of Bannockburn downwards the account of all the facts is pretty distinct, and what makes in it for Scotland can be traced as fairly as what makes for England. Throughout the preparatory stages of the dispute, and the earlier part of the actual contest, England has the whole telling of the story. "The man," who says he was on all occasions the victor, is the historian of both sides. "The lion," ever represented as beaten, is not heard. Scotland has virtually no contemporary chronicle of those ages. When the biographers of St Columba and the other saints of the Scottish Church- that is to say, of the Irish Church settled in Scotland-came to an end in the seventh century, there is a gap of nearly eight hundred years until we come up with Barbour, Fordun, and Wyntoun. There is something almost awful in such a blank in the annals of a country. One wonders

how, from the scraps of informa tion dropping in other parts of the world, it could be possible to make anything like a continuity for Scotland. But the notices taken of the country by its neighbours having been religiously treasured, have proved sufficient to tell us in a vaguish general way how several groups of tribes got into combination by degrees, and were at last articulated into a sovereign state which was named Scotland, after that portion of its population which of all the motley group had the least of Scotch character according to our modern notions—after the colony of Irish Scots who peopled Argyle and the Western Isles.

The scraps that make up this early history of Scotland are taken in some measure from the annals set down by the churchmen of that Ireland which sent forth the colony just alluded to. Another portion is found in the Scandinavian Sagas, or other chronicles; and it is worth notice in passing, as a distinction scarcely coinciding with modern notions, that whatever is descriptive, imaginative, or discursive in the early notices of Scotland, comes from these Gothic sources, while all the aid we get from the Irish Celts is set forth with a dry brevity which all Sparta could not have improved.

The great bulk, however, of the material for the history of Scotland in the time referred to is to be found in the English Chronicles. These are a great body of literature worthy of all admiration, and a just Το foundation for national pride. enumerate them, with even the briefest notice of their respective characteristics and differences, would make a longer paper than this is intended to be. They made a great national library when Bishop Nicolson wrote an account of them early in last century; they