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almost impossible to carry out any scientific or literary inquiry in a complete manner, without resorting to the great national museum. There are doubtless many things which the Trustees have not done, but is it a slight matter that they have given us, on the whole, by far the most extensive and complete body of collections anywhere brought together in the world? The library and reading-room alone are enough to do honour to their management, and it is almost impossible to fathom the degree in which this library assists every kind of inquiry. When we are least aware, we are often enjoying the fruits of investigation in that library; the late Prof. Boole, for instance, spent the last few months of his life in the Museum, pursuing an exhaustive inquiry into previous writings on the subject of Differential Equations.

As regards the other collections, I presume that no one will call in question their enormous extent; and the fact that they are not adequately lodged and displayed as yet, is due to their very vastness, and to the fact that Government would not, until lately, afford the money fjr the new buildings. As regards the real interests of original inquiry, too, comparatively little harm is done by the want of room for exhibition, since bond fiile scientific students can always obtain access to the collections.

I am far from denying that the officials who have conducted the South Kensington Museum have, by an enormous expenditure of public money, collected together a great quantity of beautiful objects of art, and have thus not only afforded opportunities for art study, but have made this museum a very agreeable and fashionable lounge. But I must protest against the notion, apparently countenanced in Nature, that the scientific value and work of a national museum is to be measured by the number of millions of persons who saunter through the galleries. No doubt the utility of a museum in affording popular instruction and tlevated amusement to large masses of people is very considerable, but this popular work is altogether of a different order from the strictly scientific object of collecting together all the products of intellect and of Nature. It is an unavoidable misfortune of the best and highest work in science that it is quite unobtrusive. The public is struck by the thousands who crowd the decorated galleries of South Kensington. There is nothing to attract public attention in the two or three hundred bookworms patiently plodding through the books in the Museum library, or the few students turning over the drawers of the zoological, botanical, mineralogical, numismatic, and other collections. But in Nature, which has so powerfully advocated the necessity of promoting original research in this country, I should expect, more than anywhere else, to find a due appreciation of the noble work which is being carried out by the British Museum trustees, and by the staff of eminent scientific and literary men who are employed under their direction in promoting almost every branch of literature and science. We have heard many complaints of the apathy displayed by Government in the promotion of science. The existence of the British Museum is the best answer to that complaint. As regards those branches of science which demand the use of large collections, it miy be regarded as the great national laboratory; and if scientific men do not make adequate use of it, that is their fault and not that of the trustees. W. Stanley Jevons

[Our opinion of the immense importance to research of the collections of the British Museum is quite in accordance with the above letter of our esteemed correspondent, and if he will read the article again he will see nothing in it to indicate any difference of opinion. Indeed we regard the positions of the scientific men in the British Museum as positions of endowed research, and positions, moreover, which have amply justified it, miserable as the amount is in many cases. Our objection is to the existence of trustees not represented by a Minister, and to the action of the trustees, who have not expanded the area of the utility of the collections, and who have cared so little for the men of science working under them and the collections themselves that the former are underpaid and the latter are much less useful than they might be. Mr. Jevons concedes the whole point when he refers to the money so properly spent at South Kensington ; for bad the British Museum been under the same Minister, money would have been spent there too. The money must be spent unless we are to sink to the level of—well, let us say Morocco; and it is to prevent this that the proposed transfer has been suggested.—Ed.]

On the Equilibrium of Temperature of a Gaseous
Column subject to Gravity

Innaturb, vol. viii. p. 486, Mr. Guthrie asks the question, "Is thre no possibility of testing the nature of thermal equilibrium of a column of still air? I think to this question an

answer may be given, which, though indirect and imperfect, will perhaps decide the controversy on the above subject.

If gravity causes in the temperature of a gaseous column the difference, which Mr. Guthrie thinks it does, that difference must be in proportion to the height of the column, and in inverse proportion to the specific heat of the gas. Hence it follows that, if two equal columns of different gases, both under the same thermal influence, are joined at their lower parts by a thermo-electric pile, the side of this pile, which is surrounded by the gas with the highest specific heat, must be constantly cooler than the other side. The result of my experiments respecting this, is the confirmation of Mr. Guthrie s opinion. The description of these experiments, and a theoretical treatise on the subject, have been in the hands of Prof. Poggendorff since the beginning of last June, ard will be published in an early number of his Annalen.

I hope that my experiments will induce others to try them in the same or in another manner, in order to bring the question concerning the influence of gravity on the thermal equilibrium to a final decision. Should it prove in favour of Mr. Guthrie's theory, as I believe it will, this theory, represented till now only by a very small minority, although it was broached twenty years ago by Waterston, * will give r.'se to results t which may perhaps clear up many of our ideas about Kosmos.

The argument which Prof. Clerk-Maxwell has brought against Mr. Guthrie in Nature, vol. viii. p. 85, does not appear to me to be generally correct. He says:—In a given horizontal stratum of a gaseous column subject to gravity, a greater number of molecules come from below than from above to strike those in the stratum, because the density of the gas is greater below than above. Certainly the number of molecules, which enter into such a stratum during a certain time, depends upon the density of the gas, but besides this, it depends upon the probability of entering into it, which exists for each molecule. Now, this probability is not only dependent upon the distance of a molecule from the stratum, upon its velocity, its direction and its encounters with other molecules, but also upon the very fact of its being above or below the stratum.

Gravity continually tends to diminish thedis'ance between any horizontal stratum and each molecule which is above the stratum, and continually tends to increase the distance between the stratum and each molecule which is below. Hence it follows that the probability of entering into the stratum will be greater for a molecule which is above than for one below, if, in the case of both, all other circumstances are equal. For example, consider two molecules, which in a given moment move with the same velocity and in the same direction on the two sides of the stratum; if this direction is horizontal like the stratum, and if in the given moment the distances of the molecules from the stratum are both very small, in the next moment the molecule above the stratum will have entered into it, while that one below will have removed from it.

In the case of the density being greater below the stratum than above, more molecules would enter it from below, if gravity did not exist. But under the influence of gravity, the effects of the difference in density can be balanced by those of the abovementioned difference in the probability, which exists for each molecule of entering into the stratum during a certain time. I even consider this last difference to be the dynamical cause of the difference in density.

Westend, near Berlin, Oct. 20 G. IlANSBMANN

Periodicity of Rainfall

As far as my own figures are concerned, the reply to Mr. Meldrum's question is very easily afforded. I agree with him that it is undesirable to use averages deduced from groups of stations variable both in the number and locality of their components. The observations which I quoted were those of a single station, Halton, St. Philip, Barbadoes.

With respect to the general question, I regret being unable to share Mr. Meldrum's evident enthusiasm, and that a very different opinion has been published in the Zeitschrijt, by Dr. Jelinek, one of the most eminent meteorologists of the present day. Itmiybe convenient to some readers to be informed that an abstract of Dr. Jelinek's article is given in "British Rainfall, 1872," together with a general rA»/«/ofthc state of the question up to the date of its publication.

Camden Square, Nov. 1 G. J. Symons

* In "On Dynamical Scqutnces of Kosmos."

t I have expounded some of these results in an abstract mechanical form in "Die Atome und ihre Bewegungen'' (Coin LcnsfeldVhe Buchh:u:dlung, ■ 871).

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though they are found everywhere else where the order and Africa north of the Sahara. The second region exists at all. consists of Africa south of the Sahara, Madagascar,

The earth's surface, considered as to its population of India, and the Indian Archipelago. The third region is the frog and toad order, may be divided into three great made up of South America and Australia, and the resemregions. The first of these is composed of Europe, blance between these two parts of the earth's surface as Northern Asia (with Japan an J Chusan), North America, | to their frogs and toads is paralleled by that as to their

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clusively constructed to pass the whole of their lives in trees that they can move along the ground only with difficulty—such is the case with the sloths. Porcupines, which in the old world have short tails, in the new world have long and prehensile ones. An animal allied to the Badger — the Kinkajou (Cercoleptes caudivolvulus)—similarly acquires in South America a long and prehensile caudal appendage. Even the Fowl and Peacock Order of Birds becomes in South America more strictly arboreal than elsewhere (being represented by the Curassows), and the very geese find there a congener [Palamedid) specially

adapted to dwell in trees and destitute (like the frog Phyllomedusa before mentioned) of a web-like membrane between the toes.

We have now advanced a further stage in seeking a reply to the question, " What is a Frog?" We have now viewed it in the light to be derived from a consideration of the more noteworthy forms of the frog's order.

We may next inquire what are its next nearest allies? What other animals of the class Batrachia constitute an order which approaches nearest to the frog's order Anoura?

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his class other creatures (insect-eating, flesh-eating, and of the squirrel kind) which more or less closely resemble some of the lower members of man's order. When, however, amongst Batrachia, we go outside that order to which the frog belongs, we find in his class no creatures whatever which present anything like such an approximation to any members of the frog's order as is presented by the mammals above referred to certain members of man's order.

The Efts (or Newts) withtheir allies—hereinafter noticed — constitute the second order Urodela of the class Batrachia.

This order is very unlike the first and already described order {Anoura), in that it is composed of creatures which in many respects are strangely divergent; and though most of the species more or less resemble our own Efts (or Newts) in shape, yet the Urodela are very far from constituting such a homogeneous group as are the Anoura.

It will be well now to review some of the more striking forms contained in the order.

The Land Eft {Salamandra), though common in Holland and France (as well as the rest of Europe), is unknown in this country.

Genera allied to the European genera Triton and Salamandra, and to the American genus Amblystoma, may have the body and tail more and more elongated and the legs reduced, as in Spelcrpes, Chioglopa, and CEdipina, till they attain the condition of Batrachoccps. The greatest excess of this development, however, is found in the North American genus Amphiuma, the minute limbs of which have either three or two toes, according to the species. These creatures are called by the negroes "Congo Snake," and are quite erroneously regarded as venomous.

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to each hind foot Passing its whole life in perpetual darkness, it is blind and colourless, except the external gills, which are red. This animal retains during the whole of life not only the gill aperture on each side, but also the external plumose gills which are transitory in the Anoura and in all the Urodela hitherto mentioned. Here then we first meet with an animal which may be said to be a permanent and persistent Tadpole, yet rather like an Eft-tadpole than like that of the Frog.

A North American Urodele, misnamed (for it is silent enough) Siren, also presents us with permanent external gills, and it offers another interesting resemblance to the tadpole of the frog in that it is furnished throughout life with a horny beak. It has also another remarkable character in which it stands alone in its class. Hitherto every rehtive of the frog has had, like it, four limbs in the adult condition. In the Siren, however, we for the first time make acquaintance with a creature belonging to the class (though not to the order) of frogs and toads, which is devoid altogether of hinder (or p.-lvic) limbs, being in this respect like the whales and porcupines amongst beasts, and like the little lizard, Chirotes, amongst reptiles.

Another North American Urodele, Menobranchus, possesses throughout the whole of life both gill openings and external gills. But it is furnished with four limbs, and in other respects more or less resembles in appearance, as it does in size, the genus Menopoina before noticed.

Finally there is a genus of this order {Urodela) which has of late presented circumstances of peculiar interest. This is the Axolotl of Mexico, which was long considered by Cuvier to be a large Eft-tadpole, possessing as it does permanent gills and gill-openings, with some other characters common to the Eft-tadpole stage of existence. At length, however, its mature condition was considered to be established by the discovery that it possesses perfect powers of reproducing its kind.

For some years, individuals of this species have been preserved in the Jardin des I'lantes at Paris, and a few years ago one individual amongst others there kept was observed, to the astonishment of its guardian, to have transformed itself into a creature of quite another gt nus— the genus Amblystoma, one rich in American specie?, Since then several other species have transformed themselves, but without affording any clue as to the conditions which determine this change—a change remarkable indeed, resulting as it does not merely in the loss of gills and the closing up of the gill-openings, but in remarkable changes with respect to the skull, the dentition, and other important structures.

There is, moreover, another and very singular fact connected with this transformation. It is that no one of the individuals transformed (although we must suppose that by such transformation it has attained its highest development and perfection) has ever yet reproduced its kind, and this in spite of every effort made to promote reproduction by experiments as to diet and as to putting together males and females both transformed, also transformed males with females untransformed, and males untransformed with females transformed. Indeed, the sexual organs seem even to become atrophied in these transformed individuals. Moreover, all this time the untransformed individuals have gone on biinging forth young with the utmost fecundity, no care or trouble on the part of their guardians being required to effect it.

A fact more noteworthy could hardly be imagined in support of the view of specific genesis put forward recently.* Heiewehave a rapid and extreme transformation taking place according to an unknown internal law of the species which trans'orms itself. No one, moreover, has been able to detect the conditions which determine such transformation (though it takes place under the eyes, and in the midst of the experiments of

* See Genesis of Species, chap. xi.

its observers). This latter fact affords abundant evidence how obscure and recondite may be the conditions which determine the transformations of specific genesis, and how utterly futile are observations as to an apparent homogeneity of readily appreciable conditions. They are so since it seems to be just such recondite ones which really determine the changes just referred to, and probably, therefore, other changes analogous to them.

It may be a question whether the genus Menobranchus may not also be a persistent larval * form, and one which now never attains its once adult form. If so, it is most probable that its lost state was similar to that of the exclusively American genus Spelerpes, the larva of which Menobranchus much resembles. With respect to Proteus and Siren no conjecture of the kind can yet be made.

Individuals belonging to the common English species (Triton crislalus) occasionally retain some of the external characters of immaturity, in spite of having attained reproductive capability; and a European species (Triton alpertris) often matures the generative elements while still, as to external appearance, more or less in its tadpole stage of existence. The adult condition, however, is normally and generally attained by it.

The geographical distribution of the Urodela is very remarkable. North America is the head-quarters of the order, and, with rare and trifling exceptions, the whole are confined to the Northern hemisphere. The exceptions are certain forms which extend down the Andes into South America, and one or two species of Amblystoma, which similarly descend along the highlands of South Eastern Asia. Urodeles are absolutely wanting in Hindostan, Africa .south of the Sahara, the Indian Archipelago, Australia, and New Zealand. As might be expected, that part of Asia which is nearest to North America, namely China and Japan, is the region of the old world most richly peopled by species of Urodela. Altogether the world's surface may be divided according to its Urodele population into three regions. The firit will comprise Europe, Africa north of the Sahara, and North Western Asia. The second will include Japan and Eastern Asia. The third will be formed by North America, with a slight extension southwards into Sou'h America—a division which by no means coincides with that indicated by the Anoura.

The above two orders {Anoura and Urodela) comprise all the animals most nearly allied to the common frog, of all those outside its own order. There, is, however, another small ordinal group of animals which remains to be here noted, because of all existing creatures they come nearest to the frog, after the Urodela.

{To be continued?)

INAUGURATION OF THE LINNEAN SOCIETY'S NEW ROOMS

OrtNiNG Address By The President

T T is now seventeen years since the Government first * recognised the claims of our Society to encouragement and assistance on the part of the State, as one which devoted itself to scientific pursuits unremunerative to its members, but tending directly or indirectly to public benefit; and since then a sense of the justness of such claims on the part of pure natural science has become gradually more general. We are no longer in the days when a Peter Pindar could turn the Royal Society and its president into ridicule as boiling fleas to ascertain whether they turned red like lobsters. The Times, instead of a short leader dismissing the British Association meetings in a similar strain of banter, devotes daily, during the time of its session, half a dozen columns to the details of its proceedings. And our own department in natural science is now admitted to be one of the most im

♦ The young of the Frog or Eft is called a larva.

portant branches of general science, specially important in its relation to our material prosperity. Our food and raiment, the essentials of life, are derived exclusively from the animal and vegetable kingdoms, and biological products contribute largely to many of our luxuries, whilst on the other hand some of the greatest calamities with which we are afflicted are due to the rapid development of animal or vegetable life. Many are the associations, under Government as well as individual patronage, devoted to the improvement and increase of useful animals and plants ; and of late attention has been also devoted to the arrest of the ravages of the noxious ones, the balance of natural selection being disturbed by the interference of agriculture and animal education. The due study of the means of restoring this balance, of turning it more and more in our favour, of calling in to our aid more and more of the hitherto neglected available species, or of the hitherto latent properties of those already in use, of checking the progress of blights and murrains, requires a thorough knowledge of the animals and plants themselves, and that thorough knowledge can only be obtained by that scientific study not only of particular animals and plants supposed a priori to be useful or noxious, but of all animals and plants, which it is the special province of our Society to promote. And in this respect I think it will be generally admitted that we have not been neglectful of our duty, and that we have done our part in rendering effective the support we have of late years received from Government as well as from individuals, and in establishing a sound claim for its increased continuance. Besides the aid afforded to scientific researches by our largely augmented library, the great value of the papers published in the recent volumes of our Transactions and Journal has been acknowledged abroad as well as at home. It is in our Society, for instance, that the great Darwinian theories were first promulgated ; and it must be recollected that the five or six hundred copies of our publications regularly sent out, place the researches they exhibit at once at the disposal of the leading followers of the science in all parts of the world. It is true that these great additions to our efficiency are not entirely due to Government patronage, but are the direct results of the reforms introduced by Dr. Hooker in 1855. Those reforms, however, would have lost much of their effect had we remained confined to our old quarters in Soho Square. Cramped for space in those obscure and dingy rooms, it required a strong devotion to science to induce an adequate attendance at our meetings ; and saddled with a heavy rent, we could neither purchase books for our library nor find room on our shelves for those presented to us.

In the spring of 1856, however, an opening was made for our obtaining rooms in Burlington House. I was then on the Council, and joined heartily in the conviction of the importance of availing ourselves of the opportunity, notwithstanding the heavy expense it might entail, which 1 felt confident we could cover by a subscription amongst our fellows. Our President undertook the preliminary negotiations, and at the meeting of our Council on June 11 a letter was officially communicated to us addressed by the Secretary of the Treasury to the President of the Royal Society, allowing the temporary location in Burlington House of the Linnean and Chemical Societies with the Royal Society, upon certain conditions; those which affected us being, that the Royal Society should be put in possession of the main building of Burlington House on the understanding that they would, in communication with the Linnean and Chemical Societies, assign suitable accommodation therein for those bodies, and that the Fellows of the three societies should have mutual access to their three libraries for purposes of reference. Our Society,Jat a special general meeting held on the 17th of the same month, authorised the Council to take the ne;essary steps for carrying out the proposal of the

Government, and in the following February 1857 the Royal Society assigned to us the rooms which we have since occupied under the above conditions. A subscription was organised which ultimately amounted to nearly 1,100/., sufficient to defray all expenses of parting with our old rooms and fitting up the new ones, with a very small surplus, which was carried to the general account. In the same month of February I was associated with our then active and zealous President and Secretary, and with Mr. Wilson Saunders as a Removal Committee, and on Tuesday June 2 the Society was enabled for the first time to meet in their new rooms.

Our position, however, although so great an improvement upon Soho Square, was not yet quite satisfactory. It was provisional only, and under the wing, as it were, of the Royal Society, and liable at any time to be exchanged for a worse or a better one as the case might turn out. This uncertainty is now removed. The Government, rightly understanding the relations which ought to prevail with the scientific societies judged to be deserving of their support, obtained from Parliament adequate means for providing ample accommodation to the six societies here located, without reserving any right of interference with or control over their scientific operations. Thus our new quarters have assumed a permanent and independent character, the rooms have been built and fitted up expressly for [our Society, and, having followed out all the arrangements, 1 feel bound to acknowledge the effective manner in which the liberal intentions of Government have been promoted and carried out in detail by the architects, Mr. Barry and the late Mr. Bankes. When the plans for the new building were first being prepared, some six or seven years' since, we were applied to for particulars of the accommodation we should require for our library and meetings, for the transaction of the business of the Society and for the residence of our librarian and porter. We were not consulted, it is true, about the general arrangements in relation to the other societies, and we have to regret the cessation of that close juxtaposition and intimate intercourse with the Royal Society which was so agreeable to us, but in all other respects our requisitions were fully complied with in the plans prepared and sent to us for approval, and the only alteration since made has been the curtailment of a portion of the basement premises in favour of the post-office, which rather inconveniently limits the stowage room for our stock of Transactions. With this sole exception wc have the space we asked for, and the bookshelves and such other fittings as have been provided by Government have been worked out in the most satisfactory manner.

Our removal here has necessarily been attended with considerable expense, the precise amount of which cannot yet be calculated, but it will probibly exceed 600/. The Council have, however, not thought it necessary to call for any special subscription. The investments made during the past year have been partially with a view to the present occasion, and the gradually increasing sale of our publications and general appreciation of the value of our labours has been so far adding to our receipts that we closed last session with a much larger balance in hand than usual, and we hope to clear ourselves of the liabilities we are incurring, without reducing our invested funds much below 2000/. At the same time, we must not conceal from ourselves that we shall be called upon for a considerable increase in our expenditure. Our enlarged accommodation, combined with high prices, will add much to our household expenses. We are threatened with a repeal of the Act which exempts us from parochial rates. Nearly the whole of our library having within the last three weeks passed through my hands, I have become convinced that it will require a large outlay in binding, as well as in filling up gaps to render it really efficient And, above all, we must bear in mind that the chief means we have of promoting the scientific objects for

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