respecting the extension of the Society's sphere of action was laid before the meeting by the president; it was determined that the matter should be discussed at the Society's next meeting. Prof. Maxwell asked for information as to the convention established among mathematicians with respect to the relation between the positive direction of motion along any axis, and the positive direction of rotation round it. In Sir W. Hamilton's Lectures on Quaternions the coordinate axes are drawn, a to South, y to West, and upwards. The same system is adopted in Prof. Tait's Quaternions, and in Listing's Vorstudien zur Topologie. The positive directions of translation and of rotation are thus connected as in a left-handed screw or the tendril of the hop. On the other hand, in Thomson and Tait's "Natural Philosophy," p. 234, the relations are defined with reference to a watch, and lead to the opposite system, symbolised by an ordinary or right-handed screw, or the tendril of the vine. If the actual rotation of the earth from west to east be taken positive, the direction of the earth's axis from south to north is positive in this system. In pure mathematics little inconvenience is felt from this want of uniformity, but in astronomy, electro-magnetics, and all physical sciences, it is of the greatest importance that one or the other system should be specified and persevered in. The relation between the one system and the other is the same as that between an object and its reflected image, and the operation of passing from one to the other has been called by Listing Perversion. Sir W. Thomson and Dr. Hirst stated the arguments in favour of the right-handed system, derived from the motion of the earth and planets, and the convention that north is to be reckoned positive. The righthanded system, symbolised by a corkscrew or the tendril of the vine, was adopted by the society. HALIFAX, NOVA SCOTIA Institute of Natural Science, March 13.-Mr. J. M. Jones, F.I..S., president, in the chair. D. J. B. Gilpin read a paper on the Mammalia of Nova Scotia, being the ninth part of a series on that subject delivered before the institute. The present paper included the common hare (Lepus americanus) and the cariboo (Rangifer cariboo) or reindeer of the province. The author stated that whilst Newfoundland and the country around Hudson's Bay were represented by the polar hare (L. glacialis) which varied in colour even to pure white, and New England on the south by the wood hare (L. sylvestris) which never varied, Nova Scotia had the American hare (L. americanus) which varied to a soiled rusty-white, and which had been confounded with both the other species. A specimen of this last species taken early in November, and which might be considered as in summer pelage, was sepia-brown with a yellow wash and coarse black hairs on the back, breast, belly, and inside the legs white, tips of ears black, and pads light rusty. One taken in December of the same year and which may be taken as a winter specimen, was soiled white with rusty streaks on the back and sides; nose and circlet around the eyes rusty; under parts, pure white; a rusty streak on fore arm always, and often upon the thigh. The only parts which remained unchanged were the white of the belly, the black ear tips and the rusty pads, and that all the hair, both, summer and winter, had a lead coloured base. The change of colour takes place during the month of December, and is the result of the summer coat being shed and replaced by the winter one. The American hare abounds in the province, keeps close covert, and is nocturnal. In concluding his remarks upon this the last of the list of rodents found in Nova Scotia, Dr. Gilpin stated that although the equator produced no arctic forms, yet we find equatorial forms side by side with boreal ones at the north; and that although the furry foot of the lynx and ermine, and the feathery one of the day owl, the winter falcon, the ptarmigan, and grouse, are the true livery of the north, yet the shrews with satin coats and naked needle-like legs brave cold 20° below zero, and the red squirrel sports with naked palms on snow of similar temperature. Passing by the three orders Edentata, Solidungula, and Pachydermata, one of which, Solidungula, was represented by the horse, an introduced species on Sable Island, and there allowed to assume the feral state, the author arrived at the Ruminantia, two genera of which only exist in Nova Scotia-the cariboo or reindeer (Rangifer cariboo) and the moose (Alces americanus). He stated that the cariboo attain in Nova Scotias the enormous height of four feet ten inches; that the horns differs in every individual, but agrees in certain typical marks. In summer they are in colour rich brown, with white necks and shoulders; in winter, all soiled white; legs brownish, with white fringe on he hoofs extending to the back hoofs. They are seen in droves of seven or eight usually, and now and then of a hundred, but are fast diminishing; not, however, by the hand of man or teeth of wild beasts, but in that noiseless way wild creatures disappear as their range is contracted by new settlements; the does producing fewer fawns, and the males becoming early barren. Nova Scotia is the most southern latitude in which the cariboo is found on the American continent, but there is a 66 permanent variety," according to Richardson, one third the size of the southern form, with larger horns and no gall bladder, inhabiting the polar region. The President read a paper on the Diurnal Lepidoptera of Nova Scotia, being the second part of a series in process of delivery before the Institute. He remarked how visibly insect faunas differed according to the geological and botanical character of the districts visited by the entomologist, and more particularly alluded to the smaller size of certain insects inhabiting the extreme north-eastern portions of the American continent, compared with individuals of the same species taken farther south. This fact was first brought to his notice by the Rev. C. J. S. Bethune, secretary of the Entomological Society of Canada, three years ago, who while identifying a small collection of Heterocera taken in Nova Scotia, observed the smaller size of Nova Scotian forms when compared with those of Western Canada. Since that date the author has compared species of other orders with British types, and found a similar peculiarity, the British being larger than the Nova Scotian. This specific change is probably owing to the difference existing in the botanical character of these separate districts, which is not far removed from each other; but he hopes to be able to pay a second and longer visit to the valley of Annapolis and the slopes of the North Mountain during the coming summer. VIENNA Imperial Academy of Sciences, March 9.-Several memoirs were communicated, of which the titles only are given, namely, "On the conversion of formic acid into methylic alcohol," by MM. A. Lieben and A. Rossi, of Turin; "On the structure and development of the earliest plumage observed in the chicken," by Dr. E. Pernitza; "On the solution of algebraic equations of any degrees, even with complex co-efficients, by means of Gauss's scheme for complex magnitudes," by M. A. Raabe; and "On the heat equilibrium between polyatomic gaseous molecules," by Prof. L. Boltzmann. Two sealed papers were also deposited.-Dr. L. Fitzinger presented the sixth section of his critical revision of the family of the Bats (Vespertiliones), embracing the genera Vespertilio and Myotis.-Prof. R. Maly communicated the results of some investigations made in the chemical laboratory of the medical faculty at Innsbruck, including an analysis of the fluid from an ovarian cyst, made by himself, with investigations of the constituents of its ash, by Prof. E. Hofmann; a notice of Trommer's sugar-reaction in the urine, and of a simple mode of preparing muriate of creatinine from that fluid, by himself; and researches upon the bodies containing sulphur in the urine, by Dr. W. Löbisch.-Prof. von Hochstetter communicated some microscopic investigations on opals, by Dr. H. Behrens, in which the author states that most opals are mixtures of various minerals, including a colourless fundamental mass, containing (microscopi cally discoverable) hydrophane, cacholong, quartz, hydrated and anhydrous oxide of iron, ferriferous silicates, metallic sulphurets and carbonates, and organic substances :-fire-opal, glass-opal, noble-opal, and hyalite are free from admixture, and the first two are structureless. The colours of the noble-opal are interference-colours, caused by their lamelle, which, however, are not tabular crystals. The double refraction discovered by Schultze in hyalite is caused by differences of elasticity such as occur in dextrin, amber, and compressed glass. The author also noticed the spheroidal structure which frequently occurs in opals.-A memoir on the circum-anal glands of man, by Dr. Gay, of Kasan, was presented by Prof. Brücke. The author describes these glands as having the greatest similarity to the large sudorific glands of the axillary cavity.-Dr. Tschermak presented three memoirs, namely, an analysis of the meteoric iron from the desert of Atacama, by Prof. E. Ludwig, as a further demonstration of its similarity to the meteoric iron of Jewell Hill; a notice of the microscopic constitution of the Lavas of Aden, by M. J. Niedzwiedski, who distinguished three species of rocks :-an obsidian containing sanidine, a trachytic lava containing plagiocuase and algite, and a felspathic basalt; and a contribution of his own to the knowledge of salt-deposits, in which he refers especially to the deposit at Stassfurt, which consists of two stages (rock-salt and kieserite-carmallite), the upper of which appears to be wanting in other salt-deposits. The author notices the minerals sylvine, and kainite, which occur scattered in this upper stage at Stassfurt, and mentions their occurrence in the saltdeposit at Kalusy, in Galicia, and partially at Hallstadt, as indications of the upper stages. He also notices the crystalline forms of the kainite and sylvine of Kalusy, and of the kieserite of Hallstadt.-Prof. L. Ditscheiner presented a memoir on some new Talbotian phenomena of interference, describing the phenomena manifested in the spectrum when the object-glass of the telescope is half-covered with crystalline plates of various thickness, whilst two Nicol's prisms are placed before the fissure and before the eye-glass.-The same gentleman also communicated a paper on a simple apparatus for the production of complementary pairs of colours with Brücke's schistoscope, and a notice supplementary to his determinations of wave-lengths, published some years ago.-M. Franz presented a memoir on the theory of simultaneous substitutions in double and triple integrals; and M. Oskar Simony noticed three mathematical problems, one belonging to the integral calculus and the two others to algebraic analysis.-Prof. A. Bauer presented a memoir on some compounds of lead with other metals, in which he showed that lead combines both with palladium and with mercury to form definite chemical compounds, having the formulæ Pd Pb and Hg3Pb2. The same gentleman communicated a paper by M. J. Stingl, an analysis of rocks and spring deposits of the Teplitz thermal district. PARIS Academie des Sciences, Morales et Politiques, April 29. -The French Institute is divided into five branches, of which the Académie des Sciences is considered the senior. All the branches meet in the same hall on different days of the week; the meetings of the Académie des Sciences take place on the Monday, and those of the Académie des Sciences Morales on the Saturday; the other sittings are not public, and the three other sections do not issue a special periodical, although they keep regular records. The Académie des Sciences Morales was 66 'not less determined than its elder brother to maintain its sittings, and they were not interrupted up to April 29. But the number of the members, which had been five for the sittings of the 15th and the 22nd, had diminished again to only three, which is the smallest for making a quorum. The presidency was given to M. Naudet, the senior member by age, who is close to his 88th year. The Académie des Sciences Morales et Politiques, which had been suppressed by Napoleon I. as being tainted with ideology,' was restored by Louis Philippe after the revolution of 1830, and M. Naudet is one of the original members, and was during many years perpetual secretary, resigning five years ago as being unable to fulfil the duties of his post. M. Leveque, one of the younger members, acted as perpetual secretary, and read over a short account of the proceedings of the last sitting. M. Pellat, the only third member present, sat on the benches, and held up his hand to approve the record. Then the reading of memoirs was proceeded with. A member of the Académie des Beaux Arts, whose name is not given to us, availed himself of the privilege granted to the academicians of every section, and took his seat by his colleague Pellat. The general public was represented by three persons. One of them was M. Mangin, a literary gentleman attached for years to the editorial staff of the Patrie. The Journal Officiel of the Commune took no notice of the proceedings, which were reported in the Versailles Officiel. It is very likely that the Académie des Sciences Morales et Politiques will be extinguished for the time by the Communist rule, and there is only a faint hope that the Académie des Sciences itself will be able to find the three members required for a quorum. But some academicians propose to advise the five academies to hold a general sitting every week, so that the chance may be increased. BOOKS Received ENGLISH.-The Sub-Tropical Garden: W. Robinson (Murray)-Horses: their National Treatment, &c., by Amateur (Ballière, Tindall, and Cox).The Builders of Babel: D. McCausland (R. Bentley).-The Meteoric Theory of Saturn's Rings: A. M. Davies (Longmans).-The Physiological Anatomy and Physiology of Man, vol. i. pt. 2: Todd, Bowman, and Beale (Longmans). PAMPHLETS RECEIVED ENGLISH.-Report of the Observing Astronomical Society, Bristol.-Brown on the Throne.-Biology v. Theology, No. 2, by Julian.-Transactions of the Society of Engineers of Scotland.-Memoirs of the Geological Survey of Ireland, Nos. 104, 113, by G. H. Kinahan,-Report of the Rugby School Natural History Society for 1870.-First Annual Report of the Natural History Society of Derry-A First Catechism of Botany, by John Gibbs.- On the Physics of Arctic Ice, by R. Brown.-Descriptions of some New Oaks, by R. Brown.-On Double Spectra, by W. M. Watts. - Proceedings of the Bath Natural History Field Club, vol. ii., No. 2-The Gold Fields of Nova Scotia, by A. Heatherington.-Report of the Palestine Exploration Fund.Science and Revelation, by R. P. Smith.-Materialistic Theories, by the Archbishop of York.-Transactions of the Clifton College Scientific Society. -Address delivered at the Anniversary Meeting of the Geological Society, by J. Prestwich.-On the Physiology and Pathology of the Lower Animals, by Dr. Lauder Lindsay.-The Historical Difficulties of the Old and New Testament, by Rev. G. Rawlinson.-Positivism: a Lecture by Rev. W. Jackson.-Transactions of the Scottish Arboricultural Society for 1870. AMERICAN AND COLONIAL.-Third Annual Report of the Noxious and Beneficial Insects of the State of Missouri, by C. V. Riley.-Report of the Fruit-Growers' Association of Ontario.-On the Solar Corona, by Prof. C. A. Young.-On a Method of Fixing Photography, and Exhibiting the Magnetic Spectra, by Dr. A. M. Mayer. FOREIGN.-Plaidoyer en faveur de Paris: W. de Fonvielle. DIARY THURSDAY, MAY 25. ROYAL SOCIETY, at 8.30.-On the Temperature of the Earth as Indicated by QUEKETT MICROSCOPICAL CLUB, at 8. ROYAL INSTITUTION, at 9.-On Bishop Berkeley and the Metaphysics of Sensation: Prof. Huxley, F.R.S. THURSDAY, JUNE 1, 1871 SCIENCE LECTURES FOR THE PEOPLE IT T is the great weakness of Science in this country that its professors are rather a mass of incoherent units than an organised body eager to influence others and themselves enjoying the privileges of such influence. Each one is apt to work too much by himself, and while he often exhibits the most rare skill in discovering truth, he too frequently leaves to others less able than he the task of bringing his labours before the world at large. masses no more that the chiefs of science are either unable or unwilling to explain to others the discoveries which they themselves have made. They are at last emerging from their seclusion, and recognise their functions as teachers of truth. "A people," says Dr. Roscoe, "whose are without knowledge and without tastes for higher things than the mere struggle for existence can come to no good." These are truthful and noble words, and point to what ought to be the future action of men of science. Their author, we learn, is constantly asked about science lectures, and he thinks that if there were the means of sending lecturers to various localities they might be of the greatest value. Now, while the man of science complains with much But to do this a common action is necessary; for it is justice that his pursuits have not been recognised by the surely too much to expect that each large town should rulers of our country, he ought not to forget that it is like- independently obtain such lecturers, and publish such wise his duty to help others, in doing which he will help a volume as that now under review. Indeed, the himself. Whatever be the faults of our rulers, they are question is a more important one than at first sight eminently sensitive to public opinion; men of science, appears; for a national society, formed with the view of therefore, have only to prove to the people that they are diffusing scientific information among the populace of a useful class in order to have their services recognised. large towns, would be the beginning of a powerful union It is really absurd to suppose that one of the most intelli capable of forcing the claims of science before the Governgent and useful bodies of men in this country could not ment of the country. Most of the leaders of science are obtain their just demands if they set themselves earnestly disposed to admit that such a union is desirable, but and unitedly to the task. They have hitherto tried to many of them object to the formation of a new body. prove to our rulers that the promotion of science will bene- For, curiously enough, in matters of administration we fit the country, but have met with only indifferent success; are all of us evolutionists, and dislike very much the let them supplement their endeavours by convincing our appearance of a new organisation that has not been rulers that to promote it will be for their own benefit, and developed by insensible degrees from some previous orthey are sure to succeed. Success, in fine, will not be at-ganisation of a humble character and living under other tained by a policy of isolation, but by leavening the whole mass of the community with the love of science, and when this is done science will rise to its just place in the councils of the nation. Many of its chiefs have now begun to perceive this, and we are glad to record the success of one of the best organised attempts that have hitherto been made to extend the knowledge and love of science among the working classes. The Science Lectures for the People, lately delivered in Manchester, have been a very great success, whether we regard the numbers who attended them, or the standing of the lecturers, many of whom came from a considerable distance in order to give their information to the people of Manchester. In the cheap and simple form in which these lectures are now published they constitute an eminently readable and instructive book, suitable for all classes. The titles of the lectures are as follows: (1) Coral and Coral Reefs, by Prof. Huxley; (2 and 3) Spectrum Analysis, by Prof. Roscoe and Dr. Huggins; (4) Coal, by Mr. Dawkins; (5) Charles Dickens, by Prof. Ward; (6) The Natural History of Paving Stones, by Prof. Williamson; (7) Temperature and Life of the Deep Sea, by Dr. Carpenter; (8) Formation of Coal Strata, by Mr. Green; (9) The Sun, by Mr. Lockyer. We are much indebted to Dr. Roscoe for arranging this admirable series of lectures, and also to Mr. T. J. P. Jodrell, who has generously defrayed the heavy expenses connected with their publication. Surely, too, the men of Manchester owe a debt of gratitude to Dr. Roscoe and his friends for this intellectual feast, the elements of which are at once so excellent and so varied. It would be presumptuous in any one man to criticise such lectures, but let it be said VOL. IV. conditions. Now, such a nucleus exists at Manchester; and as the necessity for an extended union of scientific men is strongly felt, might it not be desirable to extend the Manchester organisation into one for supplying the scientific wants of the whole community? We make this suggestion with the view of eliciting the general opinion of the scientific public. This is a transitional age, and the social elements around us appear to be ripe for such a transformation. CROOKES'S CHEMICAL ANALYSIS Select Methods in Chemical Analysis (Chiefly Inorganic). idea of its true province. It is not a mere textbook of quantitative analysis after the manner of Fresenius; nor is it, as one might be inclined to suppose, a collection simply of analytical examples designed to illustrate to students the more important determinative methods, as in the well-known and deservedly appreciated "Handbuch" of Wöhler. It aims rather at being a laboratory Vade-mecum-a sort of "Chemists' Constant Companion "-designed alike for the teacher and the taught. It presents in a remarkably clear and well-arranged manner a number of thoroughly reliable methods of analysis-some original, others modifications of older and well-known methods—of which the greater portion have been rigidly tested by the author in his own laboratory. Every working chemist must have repeatedly felt the need F of a book such as this, and in its publication Mr. Crookes has rendered an important service to the analytical chemistry of the day. The author's connection with the Chemical News has doubtless afforded him great and peculiar advantages in the compilation of the materials for his work; indeed, we notice that not a few of the most valuable processes he describes have already appeared in that journal. analysis of coal, which is here introduced, together with the blowpipe assay, constitute one of the most complete things in the book. In the midst of so much that is excellent it may seem invidious to seek for real or supposed omissions, but we venture to think that a few addenda in a future edition would add to the value of the book. For example, Bunsen's method of preparing pure platinum tetrachloride from scrap platinum, and his simple and expeditious method of recovering this metal from the residues in the process, might be an advantageous addition to the condensed description by Messrs. Teschemacher and Denham Smith of the Not the least admirable feature in the book (and herein it differs from the ordinary run of quantitative manuals) is the prominence given to methods for detecting and estimating the so-called "rare" metals. Thus we have methods given for the extraction and quantitative separa-ordinary method of estimating potash. Without doubt tion of lithium, cæsium, and rubidium; cerium, lanthanum, and didymium; glucinum and yttrium, &c. Bunsen's method of analysing platinum ores is also fully described. The discoverer of thallium may justly say that if investigators were more in the habit of looking for the "rare" elements, they would doubtless turn up unexpectedly in many minerals. But for fear that some "practical man " has already made up his mind about the character of this book, we hasten to say that by far the larger portion of it is devoted to the analytical processes connected with the more important metals and their ores. The sections on iron and copper are particularly complete, all the newest and best methods being minutely described. We may instance Matthiessen's process for the preparation of pure iron, the Mansfield method of copper assay, and Meunier's methods for the immediate analysis of meteoric iron. Under the article "Soda-ash," attention is very properly directed to the absurdity practised in the alkali trade of at one time using the old atomic weight (24) of sodium, and at another the real number in stating the value of soda-compounds, the manufacturer invoicing the strength of his ash in accordance with the basis of calculation which he knows will be employed in reporting on its quality. This custom in many cases amounts to a positive abuse, and is a constant source of vexatious complaint between buyer and seller. The author quotes an instance in which soda-ash of identical quality has been known to be invoiced, part to one customer as containing 48 per cent., part to another as 49 per cent., and part to a third as 50 per cent.; the actual percentage being 481; the separate consignments being reported also of these different strengths by the analysts in the different towns to which the goods were sent. Inasmuch as soda-ash is usually valued at so much per cent., this amounts to a fraud on the purchaser. Surely the Alkali Manufacturers' Association would consult their real interest by putting an end to such a petty sham as this. But after all this is only on a par with the iniquitous system of "high" and "low" analyses, which is a scandal to the chemistry of the day. Apropos of this we would add that those interested in the agitation which has arisen in certain chemical quarters respecting the proper methods for estimating superphosphates and phosphoric acid generally, will find ample details in this work of the reliable processes which have hitherto been devised to that end. Under the head of carbon the method of assaying animal charcoal is described, and this includes an account of Schiebler's calcimeter and the mode of using it; the account of Heinrich's inquiry into the methods for the proximate not a few of the errors to which a potash determination made by this method is liable are due to the use of impure platinum. A chapter devoted to the description of useful or improved forms of apparatus, such as the new filter-pump, would also form a valuable addition. Still we must not forget to add that Dr. Carmichael's neat and ingenious method of analysis receives its due share of attention. Nor do we see the reasonableness of making the selection of methods strictly inorganic; for surely the modifications in the process of ultimate analysis introduced by Mr. Warren cannot constitute the sum of the improvements in organic analysis, proximate and ultimate, which have come under the author's notice. But we have said enough to indicate the character and scope of this work, and imperfect as our sketch is, it will at least serve to show that the book admits of very general application. It will doubtless attain to the popularity which it merits, and the chemical community will thank the author for the worthy contribution he has rendered to its literature. T. E. THORPE IN NATURE for May 18, I find a review by Prof. Newcomb of my book on the Sun, and I beg leave to give some explana tions respecting it. It is a pity that Mr. Newcomb has received my book only so lately (about one year after the printing was finished). On this account the criticism which he makes respecting spectrum analysis and the defects of the work on that head is entirely admissible; but this is no fault of the author. Since the book was written sixteen months have elapsed, and during this time great progress has been made in this branch of science, and nobody knows it better than myself, since I find so many things to add to that chapter. But the criticism seems not so just when he reproaches the work with appearing to undertake to spare the reader the trouble of having recourse to elementary books. At the time of writing, neither of the valuable books which we have now by Roscoe and Schellen were published or had reached me, and the common treatises are very scanty in this respect, so that it was indispensable then, and perhaps even now, to indicate to the general reader the principles of the new science. In the rapid progress of discovery, a book becomes old very soon, and a reviewer must not forget that printing requires time, and that this work appeared at the very moment of the breaking out of the war, so that it was shut up in Paris for almost another six months. But a more serious criticism is that which refers to the tem perature of the sun. As this is a repetition of M. Zöllner's critique, I beg to give some explanation. It is true that I have assumed that radiation is proportional to temperature without regard to the law of Dulong and Petit, and to the condition of the surface of the body. I did not, however, ignore that law, and I have taken it into account when speaking of Prof. Kirchhoff's discoveries. But here it was quite out of place to refer to it. Indeed, the consequence of this law is that a body may have a very high temperature, and yet radiate but very little; but the law does not state that a bedy may radiate more than its own temperature allows. When we judge, therefore, of the temperature from the radiation, we certainly commit an error; but so we always judge the temperature from one part of the effect that it is capable of producing; and taking into account the law of Dulong, we should find even a higher temperature in reality in the radiant body, as is the case with the gases. The conclusion, therefore, to which I have arrived, after Mr. Waterston, is, I think, by no means excessive, but if there is an objection possible to be made, it is exactly in the direction opposite to that of my reviewer. Certainly this conclusion is at variance with that of M. Zöliner, but it agrees with the results of other observers. This high temperature besides is really a virtual temperature, as it is the amount of radiation received from all the transparent strate of the solar envelope, and this body at the outer shell must certainly be at a lower temperature. But this does not prove the incorrectness of my proposition that a thermometer dipped inside the solar envelope in contact with the photosphere, would indicate the enormous temperature that Mr. Waterston has found for the first time. P. A. SECCHI, Director of the R. College Observatory Prof. Newcomb has misunderstood my remarks about the D line in the spectrum. I have never concluded, and certainly I have nowhere stated, that "the light of the sodium lines proper is reduced." What I have pointed out is that where those lines fall on the spectrum of the electric light, and where, therefore, we should expect an increase of light, there seems to result darkness. In p. 118 I am careful to use in one place the word seem, in another the word appear. I must remind Prof. Newcomb that three countrymen of his own, Professors Harkness, Curtis, and (quite recently) Young, have supposed, with me, that the theory has been maintained, that the light of the corona is due to sunlight directly illuminating our atmosphere, and that they and Mr. Baxendell have opposed that theory as pointedly as I have. I have, however, to admit that some passages "indicating personal feeling" would have been better-much better-omitted. I should have remembered that the explanation of such personal feeling would be unknown to most of my readers. Those who know that because I advocated opinions respecting the corona, which are now all but universally admitted to be just, I was spoken of as "simply making myself ridiculous," will at least acquit me of responding as rudely as I had been attacked. But the generality of my readers had heard nothing of this and other assaults upon me. I take this opportunity of noting that Dr. Armstrong, of the London Institution, has shown me that in my account of the researches of Mr. Lockyer and Dr. Frankland I have not done the former justice. Some alterations must be made also in my narrative of the work of Dr. De la Rue and P. Secchi in Spain in 1860; much more of the credit of the results then obtained WILL you permit me to make a few comments on Prof. New-being due to Dr. De la Rue than I had judged from the narrative comb's review of my treatise upon the Sun. Soon after the work had appeared, I was informed that the account I had given of Mr. Stone's treatment of the transit observations in 1769 was not such as Prof. Newcomb would admit to be just. Knowing how much attention Prof. Newcomb has given to this subject, and his great skill as a mathematician, I was prepared to learn that I had misapprehended some points of the discussion between himself and Mr. Stone. I do not even now know to what specific statements of mine he objects; but he may rest assured that my sole object has been, and is, to give a just account of the matter. My account is in agreement with that given by Sir John Herschel, and by Admiral Manners when the Gold Medal of the Royal Astronomical Society was presented to Mr. Stone. I had also inferred from the nature of the discussions between Mr. Stone and M. Faye, and between Mr. Stone and Prof. Newcomb, that the truth lay much as in my narrative. At any rate, those who were present at the meetings of the Royal Astronomical Society in 1869 and 1870 will scarcely think that I have been led by any personal prejudices to advocate Mr. Stone's cause with undue favour, for Mr. Stone's strictures on some of my papers, and especially on papers relating to the subject of the transits of Venus, were severe even to bitterness. I believe that Prof. Newcomb's mastery of this special subject is calculated to prevent him from rightly judging my treatment of it. He sees it from too near a stand-point, and therefore unduly enlarged. I am sure that on a careful reconsideration of the matter he will feel that I could not have given a fuller account of it than I have, without spoiling the symmetry of my book. Already a seventh part of the letter-press and more than a third of the appendix (besides three plates and twenty-four diagrams) have been given to the subject of the sun's distance. I do not think that more space could very well have been spared. It remains yet to be proved that a single statement in these pages is inaccurate. I deny confidently that the distortion of the limbs of Venus and Mercury in transit has been proved to be the product of insufficient optical power. Irradiation must produce such effects to a greater or less extent; and I renew "gravely" my proposal to measure the effect, whatever its cause or causes, during the next transit. I would remind Prof. Newcomb that every observer at Greenwich noticed the effect (more or less) during the transit of Mercury in 1868. Now the Greenwich instruments are not commonly supposed to be utterly imperfect, nor the Greenwich observers wholly unskilled. Even if we admitted both these points, I should still adhere to my proposal. I or I have shown in the Monthly Notices of the Royal Astronomical Society for 1870, that those two observations which differed most widely are brought into perfect agreement when the relative breadth of the black ligament observed in each case is taken into account. in P. Secchi's" Le Soleil." Also the enunciation of the aurora theory of the corona must be assigned to Prof. Norton of America. RICHARD A. PROCTOR [With respect to the penultimate paragraph of the above letter, we need only refer to our own comments on two previous letters from Mr. Proctor, under date July 7 and August 4, 1870, which we now reprint. ED.:-"For an accurate though incomplete statement of Dr. Frankland's and Mr. Lockyer's theory of the Corona, we refer our readers to the first number of NATURE. Many of them will not be surprised to find that it is not what Mr. Proctor states it to be. Dr. Frankland and Mr. Lockyer, from their laboratory experiments, have shown that the pressure at the base of the chromosphere is small, and they have therefore stated that it is scarcely possible that a very extensive atmosphere lies outside the chromosphere. Mr. Lockyer has shown, moreover, that the height of the chromosphere as seen by the new method probably falls far short of its real height as seen during an eclipse as it was seen by Dr. Gould. A reference to the same number of this journal will also show that Mr. Proctor has misrepresented Dr. Gould's statements, which endorse the idea put forward by Dr. Frankland and Mr. Lockyer. Dr. which would almost lead to the belief that it was an atmospheric Gould has expressly stated that there were many phenomena rather than a cosmical phenomenon.' This is an opinion held by Faye and other distinguished astronomers, and Mr. Lockyer has simply shown that should this turn out to be the case, the continuous spectrum observed may be explained. Astronomers did not require Mr. Proctor to tell them what he has recently been enforcing; but, more modest than he, they have been waiting for facts, and Mr. Proctor surely is old enough to see that by attempting to evolve the secrets of the universe, about which the workers speak doubtfully, out of the depths of his moral con|sciousness, he simply makes himself ridiculous, and spoils much of the good work he is doing in popularising the science.""Still holding to our comments, we gladly state that they were not written in the spirit in which Mr. Proctor has read them. He is known to all as an astronomical worker, and our objection to his mathematical result was that it was based upon data among which the principal point at issue was accepted as proved."] Rain after Fire IN Paris, on Wednesday the 24th inst., after describing the terrible conflagrations, one of the correspondents writes thus:"A more lovely day it would be impossible to imagine, a sky of unusual brightness, blue as the clearest ever seen, a sun of surpassing brilliancy even for Paris, scarcely a breath of wind to rufile the Seine. Such of the great buildings as the spreading |