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They defeat what appears to us to be their author's most laudable object, namely, to secure to all men freedom of thought and expression on scientific matters; for in trespassing so rudely and inconsiderately beyond the limits of scientific inquiry, and indulging in wild speculations, he rather impedes than facilitates the progress of Truth.

Let us remind him, that if the organ of speech had been man's chief characteristic, he would not have been what he is. Guided by tradition alone, the multitude would have heard with satisfaction of an auto-da-in Jermyn Street, and no scientific inquirer would have been hereafter safe from martyrdom.

But are not such doctrines as we find in this work calculated to justify intolerance? Do they not give a colouring of justice to the anathemas which are, from time to time, launched against free scientific inquiry? We think they do, and our readers must decide for themselves.

If, then, it be the desire of the author and others (for he is nct the only one to whom we could refer, who, under the guise of an iconoclast appears to throw doubt upon the evidences of design, and upon the allpervading influence of a First Cause, in every natural phenomenon)-if, we say, it be the desire of the author, and others holding a high position in the scientific world, to see the veil of superstition withdrawn from human eyes, and the reign of reason ushered in, we recommend them to let the “scalpel ” alone, and to allow the force of reason to burst the larval investiture of the age. Ile who teaches the insect to free itself from the pupa-case, will, at the proper time, aid mankind in its efforts in the same direction.

This operation the author can most effectively facilitate, by pushing on in This admirable and careful physical investigations, without importing into his works speculative theories and doctrines which have all the imperfections, without any of the moral excellences of those “superstitions” that they seek to supplant-dogmas which possess neither the recommendation of convincing the reason, nor of appealing to the heart.

Heat considered as a mode of Motion. By Dr. J. TYNDALL, F.R.S. THE author of this excellent and interesting book states at the outset

1 that he has in it “ endeavoured to bring the rudiments of a new philosophy within the reach of a person of ordinary intelligence and culture.” This statement is, we think, open to some explanation or correction with respect to the phrase “ a new philosophy,” especially as it is placed at the very outset of the work. The phrase manifestly refers to the view that heat is “a mode of motion.”

To persons unacquainted with the present literature of the science of heat, or of the physical forces in general, such a view may perhaps be new; but to those who have perused the writings of Faraday, or particularly Grove, in his well-known work on “The Correlation of the Physical Forces," or of Helmholtz, Carpenter, and various other writers on the physical forces, heat, &c., such a view is not new, being abundantly and

prominently mentioned in those works; and it is less new to scientific men, all of whom have long been familiar with the idea of forces being “modes of motion.” The phrase is not, however, repeated in other parts of the book. We consider that had the words, the modern philosophy of heat, or the modern philosophy of force as applied to heat, been substituted for the words “a new philosophy,” the real facts of the case would have been more accurately described. The author has, however, in this excellent book, made this view of the nature of heat more popular and more demonstrable, by illustrating it with many beautiful experiments of his own and of other investigators, some of which are new ones. .

At page 2, the author says, “For by mastering the laws and relations of heat, we make clear to our minds the interdependence of natural forces generally.” This statement, though perfectly true, and applicable to the science of heat, is equally true and applicable with regard to each of the physical forces; and indeed it is correct of knowledge in general that a perfect acquaintance with any one branch discloses to us the interdependence of all branches of knowledge upon each other, and the general principles of that natural dependence and connection.

The experiments of boiling water by heat of friction (page 13); of igniting a mixture of air and bi-sulphide of carbon by suddenly condensing it in a glass syringe (page 29); of melting fusible alloy by rotating it rapidly between the poles of a powerful electro-magnet (page 37); of the contraction of india-rubber by heat (page 88); and the rotation of metallic balls by means of a voltaic current (page 104); some of which appear to be of the author's own devising, are carefully described and admirably illustrated.

We were sorry to see (pages 128 to 1:1), under the headings “ General Laws of Professor Forbes,” and “ Laws tested experimentally,” the comparison again brought forward of the author's more accurate conclusions with the less accurate ones of Professor Forbes respecting the vibrations produced by the contact of bodies of different temperatures; because having once shown (“ Philosophical Transactions of the Royal Society,” Part I., 1854) that the conclusions arrived at by Professor Forbes were incorrect, and having republished the paper in full in the “Philosophical Magazine,” July, 1854, and again in the form of a lecture at the Royal Institution, Jan. 27, 1854, it appeared unnecessary to repeat the results in that form; the accurate conclusions might have been described, and the refutation of Professor Forbes omitted.

In Lecture VIII. (page 248) and its appendix (page 270), is a clear and full description of that most interesting experiment, the causing a flame of hydrogen burning in a glass tube to emit a musical sound, by pitching the voice to it at a distance in a proper note, and also causing that sound to cease hy similar means.

In various parts of his book the author largely employs mental imagery for the purpose of illustrating his views. Ile speaks of the swinging of atoms (page 250); clashing of atoms (page 51); friction of atoms against pure space (page 33); the electric current knocking against the atoms, and imparting its motion to them (page 212); the passage of atoms from state of freedom to a state of bondage (page 153); the falling of atoms down great precipices (pages 149, 150); &c., &c., as though he could actually see the atoms and distinctly follow their movements.

It is desirable, and even necessary, for the purposes of scientific investigation and discovery, to habituate the mind to a great variety of hypotheses, both abstract and otherwise, and to employ such images respecting the motions of atoms, &c. as tools in the daily work of scientific discovery ; but we think such imagery, even though it be the most accordant with known facts, is not very suitable for conveying information, because of the great liability of unscientific persons to treat such conceptions as though they were real facts.

The book as a whole is beautifully written, and highly interesting on account of the number of good experiments contained in it. It is the most popular exposition of the dynamical theory of heat that has yet appeared. It contains the substance of the chief of the author's original investigations in the science of heat, particularly a valuable one on the action of gases upon radiant heat, which we have not space to criticise further than to observe that though not equal in degree of originality to the “Experimental Researches in Electricity” of his greatly talented predecessor, it represents a very large amount of labour, and manifests a high degree of accuracy in a very difficult subject.

Ilints on the formation of Local Museums. By the Treasurer of the

Wimbledon Museum Committee. London: Hardwicke. TT is every year becoming a question of greater importance how to find 1 suitable employment for the increased intelligence of the working classes. Mr. Toynbee has solved the question in his own way: he says, the educated population of our parishes are surrounded by an inexhaustible profusion of objects adapted to improve and to gratify the understanding, and yet, for want of some plan of stimulating inquiry and observation, these treasures remain almost unknown. His little book, which is written in a thoroughly practical style, contains an account of a successful attempt to establish in Wimbledon a museum upon a plan which the author hopes may be found applicable to the formation of similar institutions throughout the country.

The feature which gives the present work an especial interest is its advocacy of purely local collections. On this point the author gives the views of Professor E. Forbes: “It is to the development of the provincial museums that I believe we must look in future for the extension of intellectual pursuits throughout the land.” “When a naturalist goes from one country into another, his first inquiry is for local collections. He is anxious to see authentic and full cabinets of the productions of the regions he is visiting. He wishes, moreover, if possible, to study them apart, not mingled up with general or miscellaneous collections, but distinctly arranged with special reference to the region they illustrate. In almost every town of any size or consequence he finds a public museum; but how often does he find any part of that museum devoted to the illustration of the productions of the district? The very feature which, of all others,

would give interest and value to the collections, which would render it most useful for teaching purposes, has, in most instances, been omitted, or so treated as to be altogether useless.

The Wimbledon committee seem to have resolved that this charge should not apply to them : their museum is designated to " consist solely of such objects of interest characteristic of Wimbledon and its neighbourhood as may be found within a radius of five miles from the parish church ;" and though the district is an ordinary one, the committee are encouraged by being reminded that “the end of a local museum is not the exhibition of rare and so-called curious objects; but to develope and foster in the minds of all classes of people an interest in the common objects of nature which surround them.” On the willingness of the labouring classes to avail themselves of such opportunities as may be given them for the study of natural history, the present work contains some interesting and gratifying remarks. The author, “when busy among and intimate with many of the poor of London, distributed to several families small Wardian cases, and though of a very humble character doubtless to the benevolent mind of their inventor, not unacceptably still retaining his name. These Wardian cases consisted of an old soup-plate containing some mould, a few sprigs of lycopodium, or small ferns, and a bell-glass about six inches broad and eight high. In these glasses the poor were supplied with a constant view all the year round of the purest green leaves and the graceful forms of the slender stems bearing them. He (the author) will not soon forget the delight with which these presents were received, especially by the sick and bed-ridden, how affectionately they were watched, how they formed the subject of pleasant conversation time after time, and how some were to be seen carefully guarded after ten years' gratification had been derived from them. The price of these cases was about one shilling each.”

Many suggestions are given to facilitate the establishment and arrangement of local museums. The author recommends, as a preliminary measure, the holding of a “chat-meeting," which he thus describes : “A chatmeeting is a simplification of a soirée or a conversazione. It originated in the idea that many parishioners having in their homes interesting objects, the examination of which would afford pleasure and instruction to their fellow-parishioners, would on certain occasions gladly take these objects to a room appointed for the purpose, and display and explain them. Suppose half a dozen parishioners to bring objects on a certain evening, each parishioner taking a table, and in a quiet chatty way showing and describing to his brother parishioners the objects; one exbibitor would not interfere with another, and several pleasant chats might go on at the same time at different tables: this constitutes a chat-meeting, and with ordinary care and scarcely any trouble, a chat-meeting may be made very agrecable, entertaining, and useful.”

The work concludes with a description of the apparatus needed for the collection and examination of natural objects, and a classified list of the more useful and recent works on the animal, vegetable, and mineral kingdoms.

We have seldom read a book more exclusively directed to a single good purpose than the present. No display of learning is made, no favourite theory is upheld ; objections are answered and suggestions made, all in the simplest possible way; the author's name has to be incidentally made out by a reference to a list of the committee : not to gain applause, but to be useful, is evidently his aim, and we need hardly say that we heartily wish him success.

North Yorkshire ; Studies of its Botany, Geology, Climate, and Physical

Geography. By Journ Gilbert Baker. Longmans. 1863. 8vo.,

pp. 353. THIS is the most philosophical attempt at a local flora which has yet

been produced ; a really noteworthy work, which, although treating largely of geology and kindred topics, must be regarded essentially as a botanical book. It is in nowise a popular treatise, nor is it abstruse, yet thoroughly scientific; the author being an original observer, who is content to write objectively, simply recording his facts in logical sequence, leaving the reader to make his own inferences. llence the several sections are so far complete in themselves, that their consecutive dependance is by no means clear at a glance; the young geologist and botanist, the scientific tourist, local resident, and biological philosopher might each suppose the book made for his special use. Altogether it is well done.

The work is divided into three parts; in the first of which the geology, climate, and soils are treated with a view to their influence on the flora ; in the second part are given the physical geography and topography, showing the localities and conditions under which the rarer plants occur ; and, lastly, the botany, in which the flora is given in its relations to all these preceding circumstances.

As the studies on which it is founded have for the most part been maile in the field, it is rather a book for out-door use and subsequent reference than one of those tourists' guides which beguile the hours of travel.

The chapter on geology is illustrated with a capital geological map, coloured to show all the important stratigraphical divisions. But the text confines itself to describing the physical features-subdivisions of strata, their thicknesses and trimmings ont, appearance in the country, quarries and places where well seen-omitting all reference to the fossils and theoretical parts of the science.

The climatology also has a coloured map, showing the zones of altitude into which the Riding may be divided, which become the more interesting as corresponding for the most part with the limits of geological formations. The text gives abundant information on the zones, temperature, rainfall, winds, &c., with some account of the influences of these on cultivation and the indigenous flora.

The chapter on soils also has a coloured mar, indicating the hardness and power of absorbing moisture of the different parts of the district, outlines which, as might be expected, correspond with those of geological deposits. These conditions necessarily affect climate and physical geography, and are indispensable to understanding the distribution of the flora.

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