natural desire of the husband and father to provide as bountifully as possible for his family, when he felt that the hand of death was surely on him.

M. de Weber ascribes the indifference and the slights which so frequently fell to the artist's share in the world to his father's mean and insignificant appearance; it is a point which he presses frequently on his reader, more especially when writing of the want of all regard to him on the part of the English aristocracy. No doubt there was nothing imposing in the small, narrow-shouldered, thin, spare frame, with a limping gait occasioned by some early injury. The composer himself was accustomed to turn his own appearance into ridicule when he put on the hideous uniform of Saxon Court etiquette, and to declare that he was fit only for a wax-figure show. But he certainly must have derived some great charm of manner and expression from nature. He was evidently regarded in early life with more than complacency by the softer sex. He had a fine expressive head, although too large and too long to be in proportion with his slight stature, and somewhat encumbered by too marked and powerful a nose; his eyes were full of deep meaning, by turns benevolent, animated, and flashing, even through the disfigurement of his spectacles; his smile had the power of winning all hearts. When he appeared in England, it is true, long and wearing illness had bowed his form and crushed his genial spirit. But it is to his morbid susceptibility, mixed with a certain degree of shyness and reserve, rather than to his frail uncomely form, that his want of success in society must be attributed. A man of greater vigour of character and intellect would have found in the inconceivable popularity which some of his works enjoyed at that time amongst all classes of the people of England, an ample compensation for the imaginary slights which may have afflicted him in May-Fair.

With such elements of romance as those which the life of Carl Maria von Weber affords, it has been impossible for his biographer, in spite of all his efforts not to be' zu nouvellistisch,' to prevent the interest of his book from being in a great measure that produced by a work of fiction, and we are indebted to Mr. Palgrave Simpson for an English translation and reconstruction of these volumes, which are in more respects than one an improvement on the original.

ART. V.-1. Frost and Fire. Natural Engines, Tool-marks, and Chips, with Sketches taken at Home and Abroad, by a Traveller. By J. F. CAMPBELL. Two volumes, 8vo. Edinburgh: 1865.

2. Ice Caves of France and Switzerland, a Narrative of Subterranean Exploration. By the Rev. G. F. BROWNE, M.A., Fellow and Assistant Tutor of St. Catherine's College, Cambridge; Member of the Alpine Club. London: 1865. IT T is an ungracious task to criticise a book that has on the whole given us so much pleasure as Frost and Fire: the author's hobby-horses are so handsome in their careless vivacity, as they canter about the easy green fields of science, bound with astonishing leaps over moderate difficulties, and shy with a lissom swerve at familiar sign-posts, it seems unreasonable to have them led up for examination, to estimate their soundness and real worth, by the rules that apply to common horseflesh. But old experience teaches wariness. Imperfect sight is a very frequent cause of shying among hobby-horses and horses in general; high jumps over low hurdles show a miscalculation of difficulties, due to inexperience in the hunting-field; and unsoundness in the legs is a cogent reason for avoiding a steady-going trot on the hard highway. We must be careful lest we unguardedly put our faith in a noble-looking steed, with a flowing mane and tail, and wonderful action, who is capable of a great deal but who, nevertheless, is not sufficiently sound to carry us over the heavy stage for which he is about to be harnessed.

There are two methods of treating topics such as those that form the subject of Frost and Fire.' One is the scientific method, the other is the popular. They are almost the antipodes of one another. The author who writes a really scientific treatise confines himself to phraseology that is rigorously exact, and handles his subject with a firm and comprehensive grasp. He avoids uncertainties of expression to the utmost of his power; and he shows an abhorrence of doubtful, dark corners of thought. He states clearly what he knows, and he draws with a firm line the boundary where his knowledge ends and the obscure and the unknown begins. The model scientific writer endeavours to be concise without baldness. He trusts that his readers will be sufficiently intelligent and studious, to succeed in realising to their imaginations the ideas which he has justly, though unrhetorically, set forth.

But the writer of a so-called 'popular' treatise on science works on quite another principle. He is as careless of precision as he is regardless of thoroughness and comprehensiveness. He endeavours at one and the same time to convey new ideas, and to stimulate a torpid curiosity in his reader. He tries to do so by selecting portions of old and familiar modes of thought, expressing them rhetorically and arranging them in new combinations. He therefore deals copiously in metaphors that are partially applicable, and in allegories that have to be strained in order to be understood. His method of treatment is approximative and confused, not clear and rigorous: it is partial, not comprehensive. However ingeniously or poetically the author of a merely popular book, on any branch of science, may acquit himself, the result is necessarily imperfect; for ideas that are really new are not to be extracted, ready made, from old ones.

Frost and Fire,' notwithstanding its great and substantial merits, on which it will shortly be our pleasure to enlarge, is in its treatment a popular book; and is therefore crammed full· of the faults that necessarily attach themselves to this style of writing. It is impossible to read the work without constant fret and vexation, that it should be so inadequate to its pretensions as a whole, and yet so excellent in many of its parts. It is literally a Kosmos in design, treating of primeval forces, from their application to molten planets and the constitution of the sun, down to the latest geological changes on our earth. Beginning and ending with Kosmic theories of questionable value, the middle of it is occupied with the author's careful geological observations in north-western Europe and America. He shows that it is probable an Arctic current from the Northpolar seas swept, in ancient days, right over an almost wholly submerged Scandinavia and Britain, carrying fleets of icebergs, that scored the now elevated lands into their present configuration. This part of the work leaves little to be desired except condensation. We have also greatly to commend the author's experiments to illustrate the action of geological forces on a miniature scale, though it will be seen that we limit the professed range of their application, before we can consent to adopt them as substitutes for theory and calculation.

Frost and Fire' is by no means a book to be skimmed or lightly dealt with. It consists of two thick volumes, with plenty of matter in them. They require steady reading, more than once, before the limits of the author's meaning can be apprehended; and it is hard work to read them, for the style is quaint and the course of argument exceedingly circuitous. The reader has to travel through all the Kosmic matter to

which we take exception; and when, at last, he is fairly settled down into the more valuable part of its contents, he finds himself interrupted, over and over again, by pages and chapters of narrative or digression. These interludes are thoroughly interesting in their way, but they are superfluous; yet they cannot be skipped without risk. Every here and there the reader is liable to stumble on some remark, necessary for the development of the author's views, which seems as much out of its natural place where it lies, as some erratic block of granite perched on a hill of slate.

We will commence by showing cause for these objections, that we may be at liberty to dismiss that unpleasant part of our duty, and afterwards to follow with less interruption some of the many clues of inquiry that Mr. Campbell's volumes suggest. First of all, we object to the title. The author treats Frost and Fire,' both there and throughout his work, as antagonistic entities. Frost does this, and fire does that. Hot particles repel, cold ones attract, each other' (vol. i. p. 14). But what is heat and cold? what are frost and fire? Does he mean by frost a temperature at which pure water freezes; and by fire a temperature at which lava melts? Or what substances does he take as his standards? Melted lava freezes into stone at a hotter temperature than that of burning coal. There are plenty of fires that burn at still lower temperatures. Gun-cotton explodes in the hand without singeing it. The fundamental motive power is difference of temperature. Ice and molten lava are specific results of this difference. But the author seems never at home with abstract ideas, and prefers to express himself by concrete ones, even when they are insufficient for his wants.

Again, his fundamental and favourite axiom, where light shines, there force radiates,' is still unproven. So far as experiment has yet taught us, mere light has not much to do with force. Obscure heat seems just as potent as that which is luminous. The author devotes a large part of his work to heat, and enters minutely into its meteorological influences; yet so imperfectly does he grapple with the subject he attempts to explain, that we have been unable to find the term 'latent' heat anywhere in his pages, and the very idea of it seems pointedly ignored. Phrases like the following show a curious misapprehension of the nature of heat in its meteorological aspect:- Air in high regions is pressed by less weight. It is colder than air near the earth; but like a sponge relieved 'from pressure, it is better able to hold water the lighter it is. There is more room in it, so to speak...' (Vol. i. p. 82.)

When damp air has cooled and contracted to a certain point, it lays its load of water on any cold substance which takes in part of the charge of heat which expanded air. Vapour is condensed. It follows the heat out of the warm air to the 'cold substance, and if it cannot get in, it stops on the surface and gathers in round drops.' (Vol. i. p. 70.) He asserts here, if we comprehend him aright, that the charge of moisture air can carry depends on its state of condensation, rather than upon its temperature, which is wholly erroneous. We may mention that he nowhere makes any allusion to the specific heat of air at different degrees of condensation.

He is constantly speaking of ray-force,' by which he means much more than mere radiation. He says (vol. ii. p. 355), The subject (ray-power) is too large for unskilful hands and minds to grasp. It is dangerous even to step on such untried 'ground.' When he applies the term 'ray-force' to heat, he uses it in a more recondite sense than that of conduction or convection. These would undoubtedly be results of ray-force in the sense of force radiating in all directions equally, from every particle; but then he considers the results of ray-force as usually acting in the direction of rays; which they certainly do not. Thus the trade winds blow at right angles to the surface of the earth, whose equatorial warmth and polar cold set them in motion. The movements of machinery, moved originally by ray-force, are still more various. It is with considerable regret that we have, here and elsewhere, to express inability to understand the author's meaning, owing to his want of precision. The following passage is one out of many that could be quoted, which are to be met with in various parts of his book, alluding to ray-force. They are all of the same tissue. There is not one of them that puts his meaning into an intelligible form. The italics here, and further on, are our

own:

In hunting ice-marks, and in hunting heat, all tracks followed backwards lead to centres from which force radiates: in the one case to the pole, and to pure centrifugal force; in the other to the earth's centre, where centrifugal force and heat must both act outwards, but not in the same directions. Pure centrifugal force tends to move bodies away from an axis of rotation, in a plane at right angles to the axis. Terrestrial heat radiates in all directions; two large volcanoes are active near the South Pole, Spitzbergen is rising in the north, and volcanoes abound in low latitudes. There is a faint glimmer of earth-light in this underground darkness, and some profit may be got out of this mine, even though digging into it may be hard labour. The object aimed at was to show that where light shines, there also force radiates, and there also forms

VOL. CXXII. NO. CCL.

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