district described, and contains copious lists of the minerals and fossils discovered. The appendix is especially important to palæontologists. It embraces an account of the Cretaceous and Tertiary plants, by Dr. J. S. Newberry, Professor of Palæontology of the School of Mines, Columbia College, New York, and deals with nearly fifty species. CORRESPONDENCE. It is distinctly to be borne in mind that we do not, by inserting letters, convey any opinion favourable to their contents. We open our columns to all, without leaning to any; and thus supply a channel for the publication of opinions of all shades. No notice whatever will be taken of anonymous communications. THE PROBABLE SEAT OF VOLCANIC ACTION.-From PROFESSOR STERRY HUNT. SIR,-In SCIENTIFIC OPINION for October 27th (p. 456), the Rev. Ormerod Fisher refers to a suggestion made by him in the Geological Magazine for November, 1868, that a diminution of pressure consequent on movements in the carth's crust might cause rocks highly heated, but maintained in a solid state by great pressure, to pass into a condition of liquidity. Mr. Scrope, in the succeeding number of that magazine, asserted that this view had been advanced by him in the two successive editions of his work on Volcanos in 1826 and 1862. This claim was denied by Mr. Fisher in the magazine for January, 1869, and I having, in a paper on the probable seat of volcanic action, published in the Geological Magazine for June last, ascribed priority in this view to Mr. Scrope, Mr. Fisher, on the occasion of the republication of my paper in your journal for October 20th, repeats his charge, and calls upon me to sustain my assertion. I might with propriety rest upon Mr. Scrope's own statement in the Geological Magazine above referred to, but I venture to refer your readers to the following passages in Mr. Scrope's book on Volcanos (edition of 1862), which have probably escaped the notice of Mr. Fisher. Mr. Scrope there defines volcanic eruption as "the extravasation and ebullition of subterranean mineral matters (known, so far as we are acquainted with them, to contain water), which increased temperature or diminished pressure has liquefied and caused to effervesce" (p. 309). He elsewhere speaks of the partially liquid matter beneath a volcanic vent as varying in its condition according to circumstances of temperature and pressure, which are due to changes in position, bulk, weight, cohesion, and consequent resistance of the rocks, as well as to variation in the rate of heat from below (p. 266). Those who care to follow the question of pressure in its bearings on volcanic phenomena, are referred to a little note on this subject which I have sent to the Geological Magazine. SIR,-I have, within the last week, received a letter from Dr. Sterry Hunt, in which he has kindly referred me to a passage in Mr. Scrope's Volcanos, wherein the extravasation of mineral matter is attributed to liquefaction by increased temperature or diminished pressure. It occurs at page 309 of the edition of 1862. Thus my letter in No. 52 of your paper has been answered. I must, however, still think that there is a considerable difference between Mr. Scrope's view of the cause of volcanic outbursts and that hazarded by myself, as I pointed out in the Geological Magazine for January, 1869. I remain, &c., O. FISHER. THE NOVEMBER METEOR SHOWER IN CARACAS.-From M. A. ERNST. SIR,-I hope you will allow one of your earliest subscribers to trespass on your valuable space by remitting you for publication the results of the observation of the November meteors, as seen here in Caracas. The Sociedad de Ciencias Fisicas y Naturales de Caracas desiring to collect facts for the study of the meteors in this year, named a committee of two members (Dr. Diaz and Sig. A. Aveledo), who, accompanied by several other gentlemen, observed the heavens in the night from the 13th to the 14th November, posted in a convenient position on the flat roof of the Colegio de Santa Maria (10° 30′ 50′′ N., 69° 15′ W. Paris), 5.83 m over the street, which is 890 over the level of the Caribbean Sea. Every observer directed his attention to a certain part of the firmament, and counted loud the meteors he saw, telling at the same time the spot where they became visible, and the direction they followed. The sky was very clouded during the greatest part of the night, so that in all no more than 405 meteors could be booked, from one o'clock, when the first was visible to 5h. 34', when the last was seen in the dim light of the dawning day. Most of the meteors were only visible in a part of its way, the firmament being continually covered here and there by clouds; but, by tracing on a map the directions noted in the list, the lower were found to converge partly in Leo, partly in Perseus; 28 meteors were noticed from Ursus major. The maximum observed in five minutes was 58, at 4h. 5'; and in the last minute of these five 29 were noted. 1h. 50' 1h. 55' 2h. O' 1h. 20' 2 3h. 45' 3h. 50' 2 1h. 20' 1h. 40' 1h. 40' 0 3h. 50' 3h. 55' 5 1h. 45' 7 ... 1h. 55' 2h. O' 2h. 5' 2h. 5' 2h. 10' 2h. 10' 2h. 15' 2h. 15' 2h. 20' 2h. 20' 2h. 35' 2h. 35' 2h. 40' 2h. 40' 2h. 45' 2h. 45' 2h. 50' 2h. 50' 2h. 55' 2h. 55' 3h. O' 3h. O' 3h. 5' 3h. 10' 3h. 15' 3h. 20' 3h. 25' 3h. 25' 3h. 30' دو 5h. 10' 5h. 20' 5h. 20' 5h. 25' 5h. 25' 5h. 30' 5h. 30' 5h. 34' دو Total 405 The colour was generally whitish, like the light of most planets; but there were seen two red ones, four green ones, and one blue one. A great many left phosphorescent traces; that of the red one, from Perseus at 3h. 23', was visible for several seconds. Three reached the apparent diameter of Venus, and one surpassed it, the latter being visible through the clouds, although not even Jupiter and Sirius could be distinguished. There was no alteration noted in the barometer, at 10h. p.m. The maximum was found with 684 11mm; the minimum at 4h. a.m., with 683-81m (reduced to 0° C.).' MON CHER MONSIEUR,-I am very much gratified with the article you have written very ably on our work, Aërial Travels, and for the publishing of the last plate relating to Mr. Glashier's ascents. I think you have given some of my colleagues more than their meed of praise. And in reference to my own labours, I beg to direct your attention to the supplement I have given (see notes) on the results of Captive balloon ascents at Ashburnham Park. In perusing with some care that résumé you can ascertain the real state of affairs in aërial investigations. The era of real scientific aëronautics is not open yet, as real aërial observations suppose balloons worked essentially according to scientific principles by aeronauts, being strictly under the guidance of the scientific observers, and who themselves are really educated for the purpose. Every part of the balloon wants a scientific study and disquisition; viz., the invention of a good varnishing stuff better than linseed-oil, which is the only one used up to the present moment. Could you take the trouble to ascertain if caoutchouc dissolved by sulphide of carbon would be serviceable, if different layers, for instance, were applied severally in order to reach to a thickness of some mm. together? The inconvenience of linseed-oil is attacking the envelope, which very quickly loses every resistance by the working of air oxygen, is well known. I am aware that in some respects gas derived from coal attacks india-rubber, but the contact with coal gas being only during a few hours before the ascent, and no ascent being to be fixed for more than twelve hours, the inconvenience from 1 Our correspondent has sent us a wave diagram of the meteors, which, however, it is needless to reproduce, as his lucid account supplies all the information required.-ED. S. O. Jan. 5, 1870.] SCIENTIFIC OPINION. the gas must be nothing to the objection arising from the contact with the air. If you can find some suggestion for meeting that difficulty you will render a real service to science in publishing it, and I will be most happy in trying it if it comes within the sphere of my opportunities. Mr. Giffard has met the difficulty most cleverly in his admirable Ashburnham Park balloon, by constructing it with several envelopes, which it is impossible to use for small balloons like the one constructing now for my private use, and which will be only able to carry two persons, me and my pupil in aëronautry, at a level of 3,000 mètres, which is sufficient for my purpose. A very able speech On the 13th of December a meeting was held at the observatory under the presidence of M. Leverrier. was delivered by M. Bert, the new Professor of Physiology to the Sorbonne, on the effects of rarefaction and condensation of the air. M. Bert quoted several Aerial Voyages, and the example shown by him was the fainting of Mr. Glaisher, which you have so ably translated from the vivid description drawn by your Mr. Bert has given a very clever sugillustrious countryman. gestion for explaining why people feel so well in a balloon when at a moderate level. The diminution of pressure gives rise to an active perspiration by the innumerable pores of the skin; gases escape out of the blood, and, if the diminution of pressure is not too large, carbonic acid, which is obnoxious, will escape alone, while oxygen will remain. So in some respects moderate aeronauts will have their blood revivified not only through the lungs, but also through their skin. It shows that everything tending to promote perspiration through the skin, as the taking of a warm bath with rubbing before the ascent will be an excellent precaution. Next time that I go up into the air I will was unquestionably wrong in try the trick. I will take fresh linen too, and have my hair cleaned at the same time. But M. Bert explaining the fainting of Mr. Glaisher only by the diminution of pressure. One of the causes affecting your illustrious countryman was unquestionably the great cold, against which he was not protected. It is easy to procure warmth by warming the sand taken for ballast, or putting warm oil in a vase not closed, for fear of diminution of pressure outside leading to an explosion. Besides, Mr. Glaisher was busy taking numbers, which were entered into his aërial log-book, and are very numerous indeed. The figures in the Appendix are only a small part of them. He was writing and observing as fast as he was able to do. But when a man is observing and writing he contracts his chest, and the process of respiration is always unfree. Sometimes, principally in the case of careful observations, it is entirely stopped!! When people are located in a rarefied air they must, on the contrary, lean on their back, for having their perspiration as free or profound as possible, so that the quantity of the air gives some compensation for the rarefaction. Mr. Glaisher was far from taking that precaution which I know, from his own teaching, is so much wanted. It is not all, the ascent was so quick that mercury was falling perhaps a 4 in. per minute. Then, persons in the car were almost in the position of living beings under the pneumatic bell, where water can be congealed in summer by the evaporating process, and no other cause! If this letter was not too long, I should insist upon other theoretical considerations, showing that your illustrious countryman is far from having founded the Colonne d'Hercules in the air, which he is the first to acknowledge; I will explain all that at the next meeting, 13th of January, at the Royal Observatory, as well as many other considerations leading to the same end, and I expect I shall be able to show that man is far from having penetrated into the air to the utmost heights. Your most faithful fellow aërial traveller, W. DE FONVIELLE.' 30, Rue des Abbesses, Pari.s. But in my first query neither littoral action nor dry land are im- Weardale, Dec. 24, 1869. 1 Our correspondent has written in English, and though his style is a little vigorous here and there, we prefer to leave his letter as written, as it expresses very forcibly the writer's views.-ED, S. O. AMEBE FROM ATLANTIC SEA-BED.-From MR. C. S. WAKE. While on this subject I may state that a few days ago I observed, at the C. STANILAND WAKE. December 23, 1869. MY DEAR MR. WAKE,-Without entering into the controversy C. S. Wake, Esq., F.A.S.L. C. CARTER BLAKE, F.G.S. WHO FIRST CAPTURED PLUSIA NI ?-From MR. DORVILLE. SIR,-Having observed in SCIENTIFIC OPINION some interesting correspondence relating to Mr. Newman's British Moths, I venture to trouble you with this communication, for the purpose of drawing attention to an expression in that work calculated to mislead its readers concerning Plusia Ni, which I was the first to capture in this country, and which was introduced by Dr. Knaggs into our lists on the authority of my specimen. Mr. Newman's reputation as a naturalist makes the expression to which I allude, viz., "Is said to have been taken," carry with it a doubt as to the accuracy of Dr. Knaggs's judgment; and may lead many to infer that he was in error, and that no such insect had been captured. Surely Mr. Newman's long experience must have shown him that individual insects frequently vary, more or less, from the type-form of their species; and he should not claim for himself the sole power of furnishing an accurate description; nor should he indirectly throw doubt on the opinions of his fellow-labourers by such an expression as "is said." In order that the fact should not be subjected to a doubt, even in have submitted my insect to the inspection Mr. Newman's mind, I am, Sir, yours faithfully, of Mr. Doubleday, who pronounces it to be "a very fine specimen of Plusia Ni." Alphington, Exeter, Dec. 24, 1869. H. DORVILLE. DIPLODUS GIBBOSUS.-From MR. BARKAS, F.G.S. SIR, The Christmas holidays have afforded me a few hours leisure in which to clear off the shale from a mass of remains of Diplodus, which has been in my possession for a considerable period, and I desire to report to your readers the result of the examination. The slab in which the fossil remains are imbedded consists of a compact, The length of the piece evenly laminated, and homogeneous mass of shale, which was obtained from the Northumberland Low Main seam. of shale is 20 in., and the width is 12 in. Lying parallel to each other, and angularly across the shale are two masses of partially ossified cartilaginous matter; the length of one of the masses is 13 in. and the breadth is 4 in., the length of the second mass is 9 in. and the width 4 in.; the average thickness of these semi-cartilaginous masses is about in., but in some parts they are upwards of in. in thickness. The surfaces of the cartilage are uneven, and present in various places well elevated ridges, which appear to exhibit the natural form of the cartilage rather than the results of uneven pressure after deposition. The cartilage consists of small, flat, granular fragments, which present the appearance of coarse sandstone, when examined en masse in a fractured part of the specimen, but on the unbroken surfaces of the remains they are small, bright, and glistening, and somewhat resemble in form and size the shagreen-like dermal covering of cartilaginous fishes, or the scales of Acanthodes. Notwithstanding the roughness of the surface of the partially ossified cartilage, the shale can be lifted from it with comparative ease, and the surface of the mass remains well exposed. Upon the shale containing the masses of cartilage, and scattered unevenly over its entire surface, there are 67 well-exposed teeth of Diplodus gibbosus, they are lying in every conceivable position, and present at one glance every possible aspect of the external appearance of the teeth-fronts, backs, sides, roots, apices, &c. The average length of each tooth is in., the largest are in. long, and the smallest about in.; they are placed for the most part very nearly upon one uniform level, which corresponds with the positions of the cartilage, but at intervals where the shale has been cleared off to more than an average depth, there are distinct indications of other teeth, rendering it probable that upon and in this slab alone there are about 100 specimens of Diplodi, and these being aggregated into a comparatively small area, and deposited near masses of cartilaginous matter, make it almost certain that the whole of them belonged to one fish; and the entire absence of small teeth renders it also probable that each fish of the genus Diplodus had teeth of nearly uniform size. It may fairly be inferred that the masses of cartilage now before me belonged to the head of this coal-measure Placoid, but the order of the arrangement of the teeth is not at all indicated by the specimen in my possession, and none of the specimens in my cabinet give the least indication of the order of arrangement of the teeth. The spines of Pleuracanthus, which are supposed to belong to Diplodus, are not present on my large slab. I am yours obediently, T. P. BARKAS, F.G.S. Newcastle-on-Tyne, Dec. 25, 1869. SIR WILLIAM THOMSON versus GEOLOGY.-From Mr. MENTEATH. SIR,-To answer your correspondent "R. A." I should have to discuss matters of chemico-geologic and other detail. I must hope that he will excuse my deferring my answer. I see that I cannot leave the subject of my last letter in the state I left it there, but must continue at greater length. I think that a general treatment of the matter may be useful; and if it be said that in this manner I am taking any undue advantage, I would reply that I thus expose a larger front to attack. In what follows below, and in one succeeding communication, I shall present such a general treatment; and immediately after, I shall endeavour to answer "R. A.'s" remarks-and any other objections that may appear-as fully as your space, the patience of your readers, and my own time may permit. In the mean time, however, would remark that I do not think I am bound to produce a clear and complete explanation of the obscure facts treated by Sir W. Thomson to justify myself in considering his opinions about those facts as vague assumptions. And, further, I would add, that I do not hold the same opinion as to the importance of the subject, in itself, that appears to be entertained by "R. A." I do not admit that, as the North British Reviewer has said, "By far the grandest question in geology proper is that of the original formation and early history of the earth." But I hold that the grandeur of a question of science is chiefly commensurate with its relations to truth. And, after the example of Hutton and the other geologists to whose influence we owe the superiority of British geology, I hold that questions of cosmogony have nothing to do with the science of geology. With the materials hitherto at our disposal, such questions cannot be seriously treated by geology or by any other science, without ignoring the principles of positive philosophy-the philosophy of neither Kant nor Comte, any more than the modern atomic theory is of Democritus, but that fashion of thought to which the results of investigation have forced scientific men. If by "power of reasoning" be understood mental force, that is less exerted in mathematics than in any other intellectual pursuit. As Warburton truly says, "Mathematical demonstration is the easiest exercise of reason." Mathematical study is the very worst gymnastic of the intellect-the very worst preparative for reasoning correctly on matters (and these are only not all the objects of human concernment) in which the mind must actively precede and not passively follow the evolution of its objects. . Now mathematics are, as is universally confessed, the easiest of all sciences. Their perspicuity is excessive, and thus they only conduce to exercise the patience and attention. . . . . A man is made to "reason justly in mathematics" in the same manner in which a man is made to walk straight in a ditch.-HAMILTON, Notes to Reid. ... In pure mathematics, for instance, &c. In geology (to take an instance of an opposite kind) the most extensive information is requisite; and though sound reasoning is called for in making use of the knowledge acquired, it is well known what erroneous systems have been devised by powerful reasoners who have satisfied themselves too soon with observations not sufficiently accurate and extensive. . . . . [Jan. 5, 1870, No matter of fact can be mathematically demonstrated, though it may be proved in such a manner as to leave no doubt on the mind. It has been rightly remarked (by Dugald Stewart) that mathematical propositions are not properly true or false in the same sense as any proposition respecting real fact is so called. -WHATELY, Logic. The sciences which deal exclusively with space and time are separated by the profoundest of all distinctions from the sciences which deal with the existences that space and time contain.-SPENCER, Class. of Sc. Manipulation is to chemistry what Bacon conceived mathematics to be to science, and as such "should know her place."-GRAVILLE WILLIAMS, Handbook of Chem. Munip. I2 quote the above, especially à l'addresse of Sir W. Thomson's backer in the North British Review. And I would, further, congratulate the latter gentleman on his admirable manner of employing two of the most ambiguous terms in the English language. Mathematics," he says, "has the special advantage (possessed by no other method) of being able to estimate numerically the weight or value of every conclusion he furnishes." Now of three things one. Either this means that only that which is expressed in numbers is numerically expressed; a senseless truism. Or it means that numerical expression is equal to intellectual value; whence, a thousand absurdities equals a thousand truths. Or it means that only what is expressed in numbers has any important weight or value: then the following must be admitted, which, to prevent cavilling, I write in strict logical form :Whatever cannot be expressed in numbers has no important weight or value; The Reviewer cannot be expressed in numbers; ...The Reviewer has no important weight or value. The Reviewer himself countenances nicknaming in the present matter; I bow to his taste, and suggest that we call him Dogberry.—But I return to Sir W. Thomson. If we found a million tombstones, inscribed with characters that could be read into intelligible and simple Latin sentences, we should conclude that the people represented by them were acquainted with the Latin language. If the letters were scattered in their arrange ment, we should object to their being united so as to form an unintelligible abracadabra, however imposing to the imagination. And should a philologist inform us, that according to the principles of philo. ogy the Latin language could not have existed at the time those tombstones represented, we should reply that those principles must be drawn from all the facts concerned, and that the sooner he set to work to adapt them to the facts the better. Principles of science are simply the summed up, short-hand, results of many observations; when we reason down from principles to facts wo test the value of the principles themselves: if we find them coincide with other evidence besides that which has been considered in their adoption, they are confirmed; if not, they are weakened, for the mistake may as well be on one side as on the other. The notion of absolute truth by deductions is an ancient phantasm. Could Archimedes have found a fixed point, he might have moved the world; but no fixed point has ever yet been found, nor is there any ground of presumption that one ever will be found. This is the old striving of the Hermetics for the Stone, that often ended in the self-delusion that they had attained it; it reminds us of Paracelsus and. the brandy-bottle, with the delusive elevation of its effects. But what does Sir W. Thomson mean by the principles of naturalphilosophy? Does the contradiction he asserts really exist between those principles and the results of geology; or are there in Sir W. Thomson's arguments certain merely conjectural assumptions slipped in among truths of physics and mathematics, and on which the geological bearing of his arguments altogether depends, thus explaining why such attacks are not made or countenanced by others equally well acquainted with the principles of natural philosophy. The latter is the case. The geological bearing of Sir W. Thomson's arguments depends on the following assumptions: 1. That the heat observed in mines and other excavations represents the earth's original heat.-The question of the origin of such observed heat we know to be an extremely complex one. The science of chemical geology, raised by such observers as Bischof and Delesse, shows that many really existing causes of that heat must be at least allowed for in our estimations; and affords a strong presumption, especially considering the imperfect state of our knowledge regarding the conduction of heat in rocks, that the heat observed may be entirely due to buried organic matter, electricity, pressure, friction, and other such causes. Sir W. Thomson's choice of the view that suits his purpose can only be founded on mere conjectural assumption. 2. That the observed retardation of the earth's rotation represents the effect of tidal retardation.—It is admitted that this observed retardation may be due to variation in the quantity of ice at the poles, or to the fall of meteorites. Professor Huxley cannot be expected to show that a slight rise in the average level of the sea has taken place during the last twenty-five centuries, for the obvious reason that no means of making such a measurement exist. But, similarly, it may be asked can Sir W. Thomson show any probability that the 1 I have not a Bacon at hand. 2 Errata in last letter: principle for principles; Abaderas for Abadesas; Ballées for Vallées. Jan. 5, 1870.] SCIENTIFIC OPINION. natural condition of the universe is a state of chaotic porridge ? 3. That the present general form of the earth was acquired by consolidation from a state of fusion, and has remained unchanged ever since. This form of the earth, it has been shown (see Juke's "Manual," &c.), would naturally result from the action of denudation) with winds, currents, &c.), whatever it might have been originally. There is certainly strong reason to believe it could not have remained unchanged. This also, then, is at best a mere assumption. 4. "The estimates here are necessarily very vague, but yet, vague as they are, I do not know that it is possible, upon any reasonable estimate, founded on known properties of matter, to say that we can believe the sun has really illuminated the earth for five hundred million years." These words of Sir W. Thomson's I think relieve me from the obligation to prove by argument that his reasoning from the or an "undersun's heat is grounded on mere conjecture; and surely Sir W.Thomson does not really suppose that a "submarine wire," ground railway," are adequate representations of the necessary alternative. It is quite true that the human mind has "a wish to investigate and a capacity for investigating;" but I have always understood that a chief element of scientific discipline is the learning not to frame solutions till we have a pretty intimate knowledge of the facts concerning what we wish to explain. Now have we, as yet, any satisfactory knowledge of the facts concerning the origin and ultimate nature of the sun's heat? Has not Sir W. Thomson been too exclusively engaged with the phenomena of artificial machines when framing the principle of the dissipation of energy? And is he really so certain of the universality and adequacy of his knowledge that he can fairly call the phenomena of the sun's heat a miracle if they do not at once adapt themselves to the principles he admits? Whence comes the new universal principle of the dissipation of energy, since to it the vast field of solid facts embraced by geology is to be adapted as best it may, and the sun to be called a miracle, or else disposed of in any manner that may suit that "principle"? Such speculations may be interesting and entertaining in themselves, but when set against the serious results of science they become absurd. 66 Well, now, Sir W. Thomson's argument from the heat of the earth involves the admission of the grounds of his argument from the sun's heat; and his argument from the form of the earth involves the as the strictly cumulative" admission of the grounds of his argument from the heat of the earth; so that his reasoning is not And his arguments are altogether North British Reviewer has said. And his conclusions do not even dependent on mere conjecture. strictly follow from these conjectures; but subordinate assumptions So that his premises, being are introduced in the working out. merely conjectural, his conclusions are less than merely conjectural. Therefore, I hold that I am justified in employing the term "vague assumptions" to characterize Sir W. Thomson's objections to geology. And if it be said that I prove too much, a similar charge may be made against the arguments of Sir W. Thomson. According to these assumptions a certain superior limit is assigned as the highest allowable to geological times. Against this stands the general testimony of geologists to the necessity of admitting a much longer period, as the lowest that can be adapted, without the introduction of violent and unjustified hypothesis, to the explanation of the geological record; and over and above this testimony there stands, first, the strong probability that, owing to the imperfection of the geological record, a much longer time must be admitted; secondly, the clear possibility that the geological record, spared by the ever active processes of metamorphism, may represent but a trifling fragment of the history of the earth; and, thirdly, the remarkable absence throughout so rich a field as that of geology of any traces of a beginning, or anything affording clear presumption of an end. The principle of the degradation of energy has only very recently been introduced into physics. The principles of Hutton have been growing in strength ever since the end of the last century. That geology on these principles is geology proper, and that catastrophism is merely a temporary aberration; that the one is consistent with reason and the results of philosophy, and the other consistent with contradiction and the results of sophistry, I propose to indicate in a succeeding communication. At the same time, I shall endeavour to show that evolutionism-seemingly here a product of the peculiarly British philosophy of universal compromise-is also unjustified, and to indicate briefly the true genesis and practical bearings of the contradiction between geology and the opinions of Sir W. Thomson. For the present I find the arguments of Sir W. Thomson depend essentially on mere conjecture. As such they have no claim to modify or in any sense disturb the generalizations from facts that resume If I am mistaken in my estimation of the worth of Sir W. sics is a branch of geology. But geologists will not trouble themselves with reforming so hopeless a case as Sir W. Thomson's. Happily, the physics taught at Glasgow is not necessarily the standard of British physics any more than the geology taught thirty years ago at Glasgow (whatever that may have been) was the standard of British geology. I have indicated, I think, some of the difficulties and relations of the question; I can pretend to little more, but believe I can support what I have said. Lastly, as I may fairly be accused of undue presumption in venturing on the criticism of so difficult a matter as the discussion in hand, I would reply, that I think the subject cannot fitly be dropped after the extraordinary statement of it that has appeared in so influential a journal as the North British Review. I have waited Therefore I have ventured in hope that it would be continued by some worthier hand; but, so far as I am aware, it has been dropped. to reopen it, and am ready to defend my words. I speak as a private P. W. STUART MENTEATH. SCIENTIFIC SOCIETIES. Secretaries of Societies will oblige us by regularly forwarding "Abstracts of GEOLOGICAL SOCIETY. : DECEMBER 22ND.-Professor Huxley, LL.D., F.R.S., in the chair. where the iron band and its associated rock-masses present identical The underlying basalt gradually passes upwards into a variegated lithomarge of about 30 ft. thick, graduating insensibly into a red or yellow ochro or bole of about ft. in thickness, which passes into a dense red ochreous mass of about 2 ft., charged with ferruginous spheroids consisting chiefly of a protoxide and peroxide. The spheroids are of the average size of peas; they increase in number and size towards the upper part of the band, and not unfrequently constitute that portion of it. The line of junction between the iron band and the overlying, and usually more or less columnar basalt, is in all cases well defined, and in a few instances exhibits decided unconformability. The authors discussed the several theories that may be suggested to account for the origin of the present condition of the pisolitic ore, and proceeded to point out what appear to have been the several stages of metamorphic action by which the pisolitic ore had been elaborated out of basalt. From field observations and chemical analyses, they have been led to consider the bole and lithomarge as the resultants of aqueous action in combination with acidulated gases, which, dissolv ing out certain mineral substances, has effected the decomposition of the basalts; and to assume that the bole underlying the iron band was a wet terrestrial surface, and that the subsequent outflow of basalt effected, by its heat, pressure, and evolved gases, a reduction of the contained oxides of iron into the more concentrated form in which they occur in the pisolite, the aggregation of the ferruginous particles being a result of the same actions. The ferruginous series, which interstratified plant-beds at Ballypalidy, was next described, and demonstrated to be of sedimentary origin; the ferruginous conglomerate resulting from the degradation of the pisolitic ore, of which it is chiefly reconstructed, and of the underlying ochres. Many additions were made to the list of plant-remains from these beds; and priority of discovery of plants in the Antrim basalts was accorded to Dr. Bryce, F.G.S. Discussion. Mr. D. Forbes was not prepared to admit some of the theoretical conclusions of the authors, and objected to calling in metamorphism to account for all that was hard to be understood. He could not recognize the division of beds so similar in character into two classes. He wished to know, assuming that the iron-ore merely resulted from the decomposition of the basalt, what became of all the silica and alumina which constituted three-fourths of the mass. The origin of the pisolitic ores was, in fact, organic. In Sweden certain lakes were regularly dredged each year for the pisolitic ore still in course of formation by means of confervoid algæ. He, therefore, regarded the whole of these beds as in a certain sense sedimentary, and though due to organic agency, yet still deriving their original mineral matter indirectly from the basalt. The basalt contained a considerable amount both of phosphorus and sulphur: and if the ores had been derived directly from the basalt, both these substances would have been present in them. This was an argument against any direct metamorphism. The presence of vanadium afforded additional reason for regarding these ores as formed in the same manner as bog iron and similar ores. Sir Charles Lyell had observed in the basalts of Madeira red ochreous bands, which represented old land surfaces, in one of which Mr. Hartog and he had discovered a leaf-bed containing vegetation of much the same character as that of the island at the present day. Near Catania, in a recent lava-stream, he had seen the junction of the lava with the soil of the ancient gardens; and in character the soil now under the lava resembled the red beds in Madeira. Mr. W. W. Smith was, on the whole, inclined to admit the power of metamorphism to produce such changes as had been here effected. He commented on the advantages of employing this Irish ore for admixture with hæmatitic ore, on account of the abundance of alumina present. Possibly there had been some difference in the chemical character of the different flows of basalt. Mr. Evans suggested that the Ballypalidy beds might be the littoral deposits of a lake in which the pisolitic ores of the other parts of Antrim were deposited further from the shore, and subsequently buried under a basaltic flow. Mr. Etheridge inquired whether the pisolitic ore had been subjected to microscopic examination, with a view of finding traces of organic forms, such as Gallionella. Mr. Tate, in reply, defended his views as to metamorphic action. He thought the uniformity in thickness and character of the pisolitic ore band over so large an area showed that it could not be a lacustrine deposit. He had not as yet examined the spheroids under the micro scope. 'Notes on the Structure of Sigillaria," by Principal Dawson, F.R.S., F.G.S., Montreal."-In this paper the author criticised the statements of Mr. Carruthers on the structure of Sigillaria (see Q. J. G. S. xxv. p. 248). He remarked that Sigillaria, as evidenced by his specimens, is not coniferous; that the coniferous trunks found in the coalformation of Nova Scotia do not present discigerous tissue of the same type as that of Sigillaria; that no Conifer has a slender woody axis surrounded by an enormously thick bark; that Calamodendron was probably a Gymnosperm, and allied to Sigillari; that although Stigmaria may not always show medullary rays, the distinct separation of the wood into wedges is an evidence of their having existed; that the difference in minute structure between Sigillaria and Stigmaria involves no serious difficulty if the former be regarded as allied to Cycadaceæ ; and further, that we do not know how many of the Stigmaria belong to Sigillaria proper, or Favularia, or to such forms as Clathraria and Leioderma, which may have been more nearly allied to Lepidophloios; that the fruit figured by Goldenberg as that of Sigillaria is more probably that of Lepidophloios, or may be a male katkin with pollen; and that he has found Trigonocarpa scattered around the trunks of Sigillariæ, and on the surface of the soil on which they grew. He agreed with Mr. Carruthers in regarding Mr. Binney's Sigillaria vascularis as allied to Lepidodendron. Discussion.-Professor Morris thought that Clathraria and Lepidophloios ought to be discriminated from the Sigillariæ, as being rather more nearly allied with cycadaceous plants, especially the former. He pointed out the manner in which certain vascular bundles communicating between the centre of the stem of Sigillaria and allied genera and their bark might be mistaken for medullary rays. "Note on some new Animal Remains from the Carboniferous and Devonian of Canada," by Principal Dawson, F.R.S., F.G.S., Montreal.The author described the characters presented by the lower jaw of an Amphibian, of which a cast had occurred in the coarse sandstone of the coal-formation between Ragged Reef and the Joggins Coalmine. It measured 6 in. in length; its surface was marked on the lower and posterior part with a network of ridges inclosing rounded depressions. The anterior part of the jaw had contained about 16 teeth, some of which remained in the matrix. These were stout, conical, and blunt, with large pulp-cavities, and about 32 longitudinal striæ, corresponding to the same number of folds of dentine. The author stated that this jaw resembled most closely those of Baphetes and Dendrerpeton, but more especially the former. He regarded it as distinct from Baphetes planiceps, and proposed for it the name of B. minor. If distinct, this raises the number of species of Amphibia. from the Coal-measures of Nova Scotia to nine. The author also noticed some insect remains found by him in slabs containing Sphenophyllum. They were referred by Mr. Scudder to the Blattaria. From the Devonian beds of Gaspé the author stated that he had obtained a small species of Cephalaspis, the first yet detected in America. With it were spines of Machairacanthus and remains of some other fishes. At Gaspé he had also obtained a new species of Psilophyton, several trunks of Prototaxites, and a species of Cyclostigma. Discussion. - The president objected to the term Reptiles being applied to Amphibia, from which they were totally distinct. He questioned the safety of attributing the jaw to Baphetes, of which no lower jaw had been previously found. Mr. Etheridge remarked. that the Cephalaspis differed materially in its proportions from any in either the Russian or British rocks. "Note on a Crocodilian Skull from Kimmeridge Bay, Dorset," by J. W. Hulke, F.R.S., F.G.S.-The author described a large Steneosaurian skull in the British Museum, from Kimmeridge Bay, which had been previously regarded as Pliosaurian, and was recently identified with Dakosaurus by Mr. Davies, sen. From the agreement of their dimensions, and their occurrence near together, the author thought it probable that this skull and the lower jaw described by him last session belonged to the same individual. It differs from the Stencosaurus rostro-minor in the greater stoutness of its snout, in the presence of an anterior pair of nasal bones prolonged into the nostril, and in the number of its teeth. The author proposed to name it Steneosaurus Manseli, after its discoverer. "Note on some Teeth associated with two Fragments of a Jaw, from Kimmeridge Bay," by J. W. Hulke, F.R.S., F.G.S.-The author described some small teeth associated with fragments of a long slender snout not unlike that of an Ichthyosaur, but too incomplete to bo certainly identified. The teeth are peculiar in the great development of the cementum, which gives the base of the tooth the form of a small bulb. The exserted crowns are slightly curved, smooth, cylindrical, and pointed. The attachment to the dentary bone was probably by means of the soft tissues, and the teeth seem to have been seated in an open groove in the surface of the jaw bone. Until additional material reveals the true nature of the fossil, the author proposes to place it alone, and to call it provisionally, Euthekiodon. The following specimens were exhibited :-Fossils and Rockspecimens from Antrim, exhibited by Ralph Tate, Esq., F.G.S.; Fossils from Kimmeridge Bay, exhibited by J. W. Hulke, Esq., F.R.S. STATISTICAL SOCIETY. ON Tuesday evening, December 21, William Newmarch, Esq., F.R.S., president, in the chair, a report on the seventh international Statistical Congress at the Hague, was read by Mr. Samuel Brown, after which Mr. R. H. Inglis Palgrave read a paper on the house accommodation of England and Wales. Mr. Palgrave commenced by stating that the population of England is now, probably, better housed than at the commencement of the century. The average number of inhabitants to |