assumptions) from seven to seven thousand years must elapse, at the present rate of expenditure, before the temperature of the whole is lowered by one degree centigrade.

As regards the transformation of energy, this presumed origin of the sun's radiation is most instructive, and we have only to mention the as yet unexplained relations which have been observed to exist between solar spots on the one hand, and two such distinct phenomena as terrestrial magnetism and planetary configurations on the other, to show that the grand subject has as yet been barely sketched; and that every step towards filling in the details will be of importance as well as novelty in science.

As regards dissipation of energy, all the members of the solar and stellar systems are of course in the position of hot bodies cooling. The smaller bodies would of course be less heated by the agglomeration of their constituents than the larger; and, even if they had been equally heated, would cool faster. The original fluidity of all the larger masses is attested by their nearly spherical forms, rendered more or less oblate by their axial rotations. Dissipation by radiation takes place very freely until the surface cools sufficiently to solidify to some little depth; and is then, on account of the low conductivity of rock masses, reduced to a very slow rate. Though a great portion of the interior of the earth must be still at a high temperature, the surface temperature is not perceptibly increased by conduction through the crust. The sun, however, has been calculated to give out energy so profusely, that the radiation from one square foot of its surface amounts to 7000 horse-power. This estimate is possibly too low, as no account is taken of absorption by the matter which fills all space between the earth and sun.

But while the heat of the sun and planets is thus being lost by dissipation, the energy of their axial and orbital motions is, on account of resistance, being gradually converted into heat. This process is so slow that its effects have as yet been observed only on one of the smaller comets, but it is certain that on this account all the planets will in time fall in to the sun, whose store of energy will thus be for a short time recruited. One noticeable point in Mayer's Celestial Dynamics is the effect of tidal friction in dissipating the energy of a planet's axial rotation. [J. Thomson had worked this out eight years before, but unfortunately did not publish it.] The general tendency of tides on the surface of a planet is to retard its rotation till it turns always the same face to the tide-producing body and it is probable that the remarkable fact that satellites generally turn the same face to their primary is to be accounted for by

tides produced by the primary in the satellite while it was yet in a molten state.

Numerous and beautiful though they have been, the applications of the laws of energy to the solar system are yet merely in their infancy; and, till they have been carried into further detail, it would be presumptuous to attempt to shift the field to stellar or nebulous systems, of which our knowledge is so small in comparison.

In this short account of the discovery and development of the grand laws of nature, so far as they are yet understood, we have confined our illustrations to the simplest cases; and the reader must not imagine that we have alluded to more than a small fraction of the known facts which have been directly shown to agree with them. It is as if, in treating of the theory of gravitation, we had contented ourselves with the proof that Kepler's laws of the planetary motions follow from it, and that it enables us to compare the masses of the earth and sun; without even mentioning lunar and planetary perturbations, or precession and nutation, as far more recondite facts also perfectly explained by it.

By means of extracts, notices, and general remarks, we have sufficiently characterized the various works enumerated at the commencement of the article, with the exception of M. Verdet's Lectures. In our former article we considered them so far as they referred to the direct relation between heat and mechanical effects. We can now say of them as a whole, what we said of a part, that, though brief, they are exceedingly clear and comprehensive. As before, our objections are confined to their historical portion, and will be easily understood by the reader. We will make but two, though there are several passages equally open to unfavourable comment. Thus (p. 82) M. Verdet says

"A une somme donnée d'actions chimiques de nature donnée doit correspondre un dégagement constant de chaleur, quelle que soit la constitution de la pile et du circuit où les deux phénomènes se produisent à la fois. Cette conclusion théorique a été vérifiée par une remarquable expérience de M. Favre "

As we have already mentioned, Joule, in 1843, showed by experiment that—

"However we arrange the voltaic apparatus, and whatever cells of electrolysis we include in the circuit, the whole caloric of the circuit is exactly accounted for by the whole of the chemical changes."

The earliest of M. Favre's experiments was published in 1853.

Again (p. 101), M. Verdet says—

Lorsque l'animal est en repos, ce travail a pour équivalent la quantité de chaleur que l'animal dégage incessamment pour compenser la perte de chaleur due au rayonnement, au contact de l'air et à l'évaporation. Lorsque l'animal est en mouvement, une portion du travail des affinités chimiques a pour équivalent le travail effectué par ce mouvement; le reste seulement se convertit en chaleur, et par conséquent à une même somme d'actions chimiques produites dans l'intérieur de l'organisme, doit répondre un dégagement de chaleur moindre dans l'état de mouvement que dans l'état de repos.

"Ces idées introduites pour la première fois dans la science en 1845, par Jules-Robert Mayer, font faire à la physiologie générale un progrès, etc."

What is this but a mode of stating, somewhat less concisely than Joule had done in 1843, the hypothesis that

If an animal were engaged in turning a piece of machinery, or in ascending a mountain, I apprehend that in proportion to the muscular effort put forth for the purpose, a diminution of the heat evolved in the system by a given chemical action would be experienced"?

It is, no doubt, to be ascribed to the facts that Joule's papers appeared only in the Philosophical Magazine, and that some of his most valuable remarks were made in the Appendix to one of them, that these important discoveries have been thus attributed to others.

Mr. Trollope's Novels.

ART. IV.--1. The Warden. By ANTHONY TROLLOPE.

Edition. London, 1861.

369

New

2. Barchester Towers. By ANTHONY TROLLOPE. New Edition. London, 1861.

3. Dr. Thorne. By ANTHONY TROLLOPE. New Edition. London, 1861.

4. The Three Clerks. By ANTHONY TROLLOPE. New Edition.

London, 1860.

5. The Bertrams.

London, 1860.

By ANTHONY TROLLOPE. Third Edition.

6. Framley Parsonage. By ANTHONY TROLLOPE. London, 1861. 7. Orley Farm. By ANTHONY TROLLOPE. London, 1861-62. 8. The Small House at Allington. By ANTHONY TROLLOPE. London, 1864.

9. The Macdermots of Ballycloran. By ANTHONY TROLLOPE. New Edition. London, 1861.

SIR WALTER SCOTT somewhere compares the critic who selects an entertaining novel for the subject of his invidious labours, to the mischievous child who plays with his new toy to-day, and finds a still more exciting amusement in tearing it in pieces to-morrow; and it must be owned there is something almost ungrateful in coldly dissecting books that are written for our amusement after they have served their purpose of amusing us. On the other hand, novels now-a-days are not quite so humble in their pretensions that the simile of the child and his toy should indicate the relation between them and their readers. Even if they are not written with the object of illustrating or refuting any particular theory of life, or system of morals, or doctrine of theology, it is impossible for a man of any mental power at all to invent human beings and set them in motion without touching, expressly or by implication, the problems of human existence. If the world be a school in which we cannot live a day without learning something, no true picture of the smallest fragment of it can be altogether insignificant; and though few people, now that Miss Edgeworth is forgotten, read novels for the purpose of improving their minds, it is only very happily constituted persons that can be certain of always escaping that result. And, indeed, the functions of criticism would be miserably curtailed if amusing novels were considered too sacred, or dull ones too trivial, for handling. It is probable that the writing of such books at this moment absorbs more talent than any other literary pursuit ; and it is certain that no amusement is so universal as the reading of them. The popularity of a novelist who is popular at all is so enormous that every suc

cessful novel, good or bad-and some very bad novels have been among the most successful-is a phenomenon worth studying. Such a study will be far from fruitless if it only convince us how little ability, imagination, or culture, it takes to set all England talking. This humiliating conviction, we are afraid, would be only too often the result of an analysis of the novel of the season; and it would not be at all uninteresting to investigate the sources of so much unmerited popularity. Our present task will be less amusing, but certainly much more agreeable; for if bad novels sometimes fascinate a deluded public, neither do good ones often fail of success; and Mr. Anthony Trollope's have unquestionably deserved their good fortune.

The novelist par excellence of the moment is assuredly Mr. Trollope. His works can by no means be placed in the highest rank; but within their own range, nothing better ever came from an English novelist. In our view, it is no drawback to their merit that they are the books of a man whose peculiar temperament is scarcely that of the literary artist. If we may judge on such a point from his writings, we cannot help thinking it a happy accident that Mr. Trollope should have written books at all. The wit and liveliness of his story and dialogue, and the simplicity, ease, and vigour of his style-an admirable style are unquestionably the graces of a master of his craft. But the whole tone and habit of mind implied in these novels is that of a man of activity and business, rather than of a man of letters. His books are the result of the experience of life, not of the studious contemplation of it. A rare degree of talent was required for their production, but the kind of talent which was required is not, perhaps, uncommon. Books like Barchester Towers are certainly not very numerous; and therefore it may be assumed that the writers are few, who possess such gifts as the author of Barchester Towers. And yet it is probable that the same powers of observation, the same shrewdness, good sense and humour, are expended every day on the common affairs and common amusements of life by people who never dream, or who only dream, of writing novels.

The great charm of Mr. Trollope's novels seems to lie in this circumstance. While we read them we are made to share, in the easiest way, the experience of a man who, in going through his own daily business, has been brought in contact with an immense variety of people; who has looked at so much of the world as it came in his way to consider, with a great deal of keenness, kindness, and humour; who thoroughly understands, because he shares the thoughts and feelings of the majority of educated Englishmen; and who sets himself to describe his own