we not hear a little less frequently than we do that research is a sham, and that all attempts to aid it savour of jobbery? Lastly we may consider Faraday's place in the general history of Science; this is far from easy. Our minds are still too much occupied with the memory of the outward form and expression of his scientific work to be able to compare him aright with the other great men among whom we shall have to place him. Every great man of the first rank is unique. Each has his own office and his own place in the historic procession of the sages. That office did not exist even in the imagination, till he came to fill it, and none can succeed to his place when he has passed away. Others may gain distinction by adapting the exposition of science to the vary. ing language of each generation of students, but their true function is not so much didactic as pædagogic-not to teach the use of phrases which enable us to persuade ourselves that we understand a science, but to bring the student into living contact with the two main sources of mental growth, the fathers of the sciences, for whose personal influence over the opening mind there is no substitute, and the material things to which their labours first gave a meaning. Faraday is, and must always remain, the father of that enlarged science of electro-magnetism which takes in at one view, all the phenomena which former inquirers had studied separately, besides those which Faraday himself discovered by following the guidance of those convictions, which he had already obtained, of the unity of the whole science. no other meaning than that assigned to them by their definitions. He thus undertook no less a task than the investigation of the facts, the ideas, and the scientific terms of electromagnetism, and the result was the remodelling of the whole according to an entirely new method. That old and popular phrase, "electric fluid," which is now, we trust, banished for ever into the region of newspaper paragraphs, had done what it could to keep men's minds fixed upon those particular parts of bodies where the "fluid" was supposed to exist. 66 Faraday, on the other hand, by inventing the word dielectric," has encouraged us to examine all that is going on in the air or other medium between the electrified bodies. It is needless to multiply instances of this kind. The terms, field of force, lines of force, induction, &c., are sufficient to recall them. They all illustrate the general principles of the growth of science, in the particular form of which Faraday is the exponent. We have, first, the careful observation of selected phenomena, then the examination of the received ideas, and the formation, when necessary, of new ideas; and, lastly, the invention of scientific terms adapted for the discussion of the phenomena in the light of the new ideas. The high place which we assign to Faraday in electromagnetic science may appear to some inconsistent with the fact that electromagnetic science is an exact science, and that in some of its branches it had already assumed a mathematical form before the time of Faraday, whereas Faraday was not a professed mathematician, and in his Before him came the discovery of most of the funda-writings we find none of those integrations of differential mental phenomena, the electric and magnetic attractions and repulsions, the electric current and its effects. Then came Cavendish, Coulomb, and Poisson, who by following the path pointed out by Newton, and making the forces which act between bodies the principal object of their study, founded the mathematical theories of electric and magnetic forces. Then Örsted discovered the cardinal fact of electro-magnetic force, and Ampère investigated the mathematical laws of the mechanical action between electric currents. equations which are supposed to be of the very essence of an exact science. Open Poisson and Ampère, who went before him, or Weber and Neumann, who came after him, and you will find their pages full of symbols, not one of which Faraday would have understood. It is admitted that Faraday made some great discoveries, but if we put these aside, how can we rank his scientific method so high without disparaging the mathematics of these eminent men? exact science without understanding the mathematics of It is true that no one can essentially cultivate any that science. But we are not to suppose that the calcu lations and equations which mathematicians find so useful constitute the whole of mathematics. The calculus is but a part of mathematics. Thus the field of electro-magnetic Science was already very large when Faraday first entered upon his public career. It was so large that to take in at one view all its departments required a stretch of thought for which a special preparation was necessary. Accordingly, we find Faraday endeavouring in the first place to obtain, from each of the known sources of electric action, all the pheno-matical science established without the aid of a single mena which any one of them was able to exhibit. Having thus established the unity of nature of all electric manifestations, his next aim was to form a conception of electrification, or electric action, which would embrace them all. For this purpose it was necessary that he should begin by getting rid of those parasitical ideas, which are so apt to cling to every scientific term, and to invest it with a luxuriant crop of connotative meanings flourishing at the expense of the meaning which the word was intended to denote. He therefore endeavoured to strip all such terms as "electric fluid," "current," and "attraction" of every meaning except that which is warranted by the phenomena themselves, and to invent new terms, such as "electrolysis,” “electrode," "dielectric,” which suggest The geometry of position is an example of a mathecalculation. Now Faraday's lines of force occupy the same position in electromagnetic science that pencils of lines do in the geometry of position. They furnish a method of building up an exact mental image of the thing we are reasoning about. The way in which Faraday phenomena of magneto-electric induction* shows him to made use of his idea of lines of force in co-ordinating the have been in reality a mathematician of a very high order *To estimate the intensity of Faraday's scientific power, we cannot do better than read the first and second series of his Researches," and compare them, first,with the statements in Bence Jones's "Life of Faraday," which tells us the tales of the first discovery of the facts, and of the final publication of the results, and second, with the whole course of electromagnetic science since, which has added no new idea to those set forth, but has only verified the truth and scientific value of every one of them. -one from whom the mathematicians of the future may regarding the former extension of glaciers.* When he showed his derive valuable and fertile methods. For the advance of the exact sciences depends upon the discovery and development of appropriate and exact ideas, by means of which we may form a mental representation of the facts, sufficiently general, on the one hand, to stand for any particular case, and sufficiently exact, on the other, to warrant the deductions we may draw from them by the application of mathematical reasoning. From the straight line of Euclid to the lines of force of Faraday this has been the character of the ideas by which science has been advanced, and by the free use of dynamical as well as geometrical ideas we may hope for a further advance. The use of mathematical calcula tions is to compare the results of the application of these ideas with our measurements of the quantities concerned in our experiments. Electrical science is now in the stage in which such measurements and calculations are of the greatest importance. We are probably ignorant even of the name of the science which will be developed out of the materials we are now collecting, when the great philosopher next after Faraday makes his appearance. LETTERS TO THE EDITOR [The Editor does not hold himself responsible for opinions expressed by his correspondents. No notice is taken of anonymous communications.] Tyndall and Tait I HAVE hitherto refrained from intruding upon your space with reference to this deplorable Forbes' controversy, but now that the occasion has come when a brief deliverance on my part seems called for, I trust to your courtesy, if not to your justice, to allow me room for it. In the first place I would ask permission to inform such of your readers as may feel an interest in the subject, that if they wish to form a correct opinion of the tone and logic of my rejoinder to Principal Forbes and his biographers, they will consult the rejoinder itself, as published by Longmans, and not the extracts and inferences of Professor Tait. They will thus learn, among other things, that what Professor Tait calls "plausible," is simply unanswerable. With regard to the taking up of the various points in Principal Forbes's reply, item by item, that may be done some day should I deem it a worthy occupation. In my rejoinder I converged attention on the two points which Principal Forbes himself considered the really serious ones, and having broken the neck of the argument in both these cases I cared little about prolonging the controversy. Nevertheless if circumstances show it to be necessary it may be prolonged. Professor Tait invariably writes on the hypothesis that what is not contradicted cannot be contradicted, and must therefore be accepted as true-a natural, if not inevitable, assumption on his part. For example, Forbes's argument regarding the cre vasses of Rendu was left unanswered by me, hence the conclusion that it was unanswerable. That argument, however, is now in shreds, as it might have been, had I so willed, any time during the last dozen years. Again, Principal Forbes makes an asser. tion regarding his tutelage of Agassiz ; the assertion is left uncontradicted; it must therefore be accepted as true, and I am unjust because I do not so accept it. Thirteen years ago, however, I was in possession of a diametrically opposite assertion from M. Agassiz. Quite as distinctly, though not so specifically, he writes thus within the present year. "When Forbes came to visit me upon the glacier of the Aar, he knew not only everything that I had done, but also my plans for the future. When he left he positively declined to express any opinion concerning glacier phenomena, under the plea that he only came to gratify his curiosity, and had no intention of following up the subject, as he had no desire to be involved in the controversy then raging hand I did not enter into a protracted discussion, but simply With statements of this character confronting the assertions of Principal Forbes, the proper course for me was to ignore assertions on both sides, and to confine myself to demonstrable facts. This I accordingly did. With regard to Mr. Tait's criticism of my "popular" writings it has, of course, nothing to do with his defence of Forbes, but is the product of mere ignoble spite. He asks me to reply to him not according to the letter, but according to the spirit of his attack. If I might use the expression I would say, "God forbid!" for how could I do so without lowering myself to some extent to his level. The antecedents of Mr. Tait with reference to me are pretty well known. When I sought to raise from the dust a meritorious man whose name is now a household word in science, who has been elected by acclamation a member of the French Academy, and who has received the crowning honour of the Royal Society-when I sought to place Dr. Mayer in the position which he now holds, and from which no detraction can remove him, it was Mr. Tait who, in Good Words, charged me with misleading the public; who followed publicly hoisted by his own petard, retired to void his venom up his attack in the "Philosophical Magazine," and who when against me in the anonymous pages of the "North British Re view." It is this man whose blunders and whose injustice have been so often reduced to nakedness, without ever once showing that he possessed the manhood to acknowledge a committed wrong, who now puts himself forward as the corrector of my errors and the definer of my scientific position. That position is happily not dependent upon him, and his opinion regarding it, is to me, as it will be to most others, a trifle light as air. But graver considerations than mere personal ones here arise. Might I venture, Mr. Editor, to express a doubt as to the wisdom of permitting discussions of this kind to appear in your invaluable journal. Having opened your columns to attack you are, of course, in duty bound to open them to reply, but if I might venture a suggestion, you would wisely use your undoubted editorial rights, andconsult the interests of science, by putting a stop to proceedings which dishonour it. An illustrious person writes to me thus :-"I have just read Professor Tait's letters in NATURE, and feel a recurrence of that pain which similar communications once inflicted on myself-pain felt, not on my own account, for I knew that the attacks would no more sully me in the opinion of those whom I loved and respected, than they did in my own opinion; but pain for the wounded honour of science and the outraged dignity of scientific controversy." JOHN TYNDALL Athenæum Club, Sept. 16 [We deeply sympathise with Professor Tyndall's remarks on the injury done to scientific controversy by the introduction into it of personalities, and we should have made his own letter square with his canon if his reference to our duty in this matter, and his insinuation of injustice did not take the matter out of our hands. Prof. Tyndall forgets (1) that Prof. Tait's letter is an answer to a pamphlet by Dr. Tyndall, and that space was asked for it as such; and not an attack in the sense in which Prof. Tyndall uses the word; (2), that if the Editor were to assume the power and responsibility that Prof. Tyndall suggests, NATURE might easily fall from the position of absolute justice and impartiality in all scientific matters which it now occupies and become the mere mouthpiece of a clique. What the Editor can do and has endeavoured to do in this case, is to guard the reputations of men of Science against the attacks of mea of straw, and to see that no personalities are used; and it is under strong protest that he allows to pass in Prof. Tyndall's letter, for the reasons already stated, personalities, the equivalents of which, the Editor, in the exercise of his "undoubted editorial rights," struck out of Prof. Tai.'s communication.-ED. NATURE. ] * This tallies with Forbes's own account (Travels, page 38). "Far from being ready to admit, as my sanguine companions wished me to do in 1841, that the theory of glaciers was complete, and the cause of their motion certain, after patiently hearing all they had to say, and reserving my opinion, &c," This reservation of opinion is probably the reticence referred to by Agassiz. FIGS. 4 & 5.-Gnathopha sia gigas, v. W.-S. there are characters presented by the new genus, particu- | larly in connection with the dorsal shield, which not only entirely separate it from Lophogaster, but enlarge our views on the whole Schizopod group. In both species the shield is sculptured by ridges traversing it in different directions, and in both there is a long spiny rostrum; but this shield is merely a soft duplicature of the skin, connected with the body only anteriorly, and leaving five horacic segments entirely free. In the structure of the FIG" 6 FIG. 5 FIC, 6.-Gnathophansia zoea, v. W.-S. shield and its mode of attachment Gnathophansia has the greatest resemblance to Apus among all crustaceans, but it differs from it widely in all other respects. Nebalia is the only Schizopod in which the carapace is not connected with the posterior thoracic segments, but in that genus the form of the carapace is totally different, and the genera are otherwise in no way nearly related. Neither the antennæ, nor the scales, nor the parts of the mouth present any marked differences from those of Lophogaster, with the exception of the second maxillæ. These, with nearly the same form as in the Norwegian genus, bear a pair of accessory eyes. Such eyes are well known at the base of the thoracic and even of the abdominal limbs in the Euphansidæ, a family with which the Lophogastridæ have otherwise nothing in common, but hitherto they have not been met with in any other animal or in any of the manducatory organs. Of the eight pairs of legs seven are ambulatory, only the first pair is, as in Lophogaster, transformed into maxillipeds. The gills are arborescent and attached to the bases of the legs. The abdomen and its appendages scarcely differ from those of Lophogaster. We find here also that the last segment is apparently divided into two. This would indicate an approach to such forms as Nebalia, which has nine abdominal segments, or at all events a tendency to a multiplication of segments which if really existing would scarcely allow the association of the genus with the true Schizopods. The weather was remarkably fine. During the day the island of Flores was visible like a cloud on the horizon, about 50 miles to the northward. In the afternoon we obtained a series of temperature soundings at intervals of 100 fathoms down to 1,000, and in the evening proceeded under steam towards Fayal. On the following day, the 1st of July, we sounded in 1,350 fathoms, about 20 miles west of Fayal, apparently in a depression which separates the western group of the Açores, Flores and Corvo from the central group Fayal, Pico, San Jorge, Terceira, and Gracioza, and during the afternoon we gradually approached the fine island of Fayal, and enjoyed the development of its bold outlines and rich and varied colouring. In the evening we passed into the narrow channel between Fayal and Pico, and anchored in the roadsteads of Hortes. We found to our great disappointment that small-pox was prevalent in Fayal, and as Captain Nares considered it imprudent to give general leave, one or two of us only landed to pick up what general impression we might of the appearance of the place, and on the following morning we proceeded towards San Miguel, first taking a few hauls of the dredge in shallow water between Fayal and Pico, where we found a rather scanty fauna, resembling in character that of southern Europe, on a bottom of dark volcanic sand. On Friday, July 4, we sounded in 750 fathoms on a rocky bottom. The ship water-bottle was sent down and brought up a sample of the bottom water. In the afternoon we shortened and furled sails, and proceeded under steam towards San Miguel, and in the evening stopped abreast of Ponta Delgada, the capital of the island, where we lay-to for the night, secured to a buoy. Next morning, as we found, greatly to our satisfaction, that the town was considered free from any epidemic of small pox, we steamed in to the anchorage, and cast anchor in 13 fathoms. We remained at San Miguel until Wednesday the 9th. We were well aware that the time at our disposal was quite insufficient to enable us to do anything of importance to add to the knowledge of the natural history of the island already so well worked out, and as we had had a long sea-cruise, we were in no way disinclined for a few days of complete relaxation. We accordingly combined into a large party, totally unscientific in its object, and by the aid of mules and donkeys made a most enjoyable raid among the caldeiras and volcanic ranges of the east end of the island. The random impressions collected during these horæ subseciva may perhaps be chronicled elsewhere. Our first haul after leaving Ponta Delgada, was in 1,000 fathoms, mid-way between the islands of San Miguel and Santa Maria, and about fifteen miles north-west of the Formigas. The bottom was Globigerina ooze. The principal feature in this dredging was the unusual abundance of stony corals of the deep-sea group. Two living specimens of a large species of Flabellum were sifted out, the same as the one which we had dredged previously at station 73, to the west of Fayal. The corallum is wedge-shaped, the calicle rising from an attenuated pedicle. The extreme height, from the end of the pedicle to the margin of the cup, is 50 mm. ; the greatest diameter of this calicle is 65 mm., and the smallest 30 mm. The three species are very nearly of the same dimensions. The lateral costæ make an angle with one another of 120° to 140°, and are sharp and moderately prominent, with an irregular edge. The external surface of the calicle is covered with a glistering epitheca, and near the margin is of a light pink colour. The cost of the faces corresponding to the primary and secondary septa are almost as well marked as the lateral costæ, and appear as irregularly dental ridges, separated by slight depressions. The ends of the calicle are broadly rounded, and it is compressed laterally in the centre. The upper margin is curved, describing about one-third of a circle. There are six systems of septa disposed in five cycles. The septa are extremely thin and fragile. They are tinged with pink, and covered with rounded granules, disposed in rows. The primary septa are approximately equal to the secondary, giving somewhat the appearance of twelve systems. These septa are broad and prominent, with a rounded superior margin, and curved lines of growth. The septa of the third, fourth, and fifth cycles successively, diminish in breadth, and are thus very markedly distinguished from one another, and from the primary and secondary septa. The septa of the fourth cycle join those of the third a short distance before reaching the columella. The septa of the fifth cycles are incomplete. The margin of the calicle is very deeply indented, the costal corresponding to the primary and secondary septa being prolonged in conjunction with the outer margins of these septa, into prominent pointed processes; similar but shorter prolongations accompany the tertiary, and some of the quaternary septa. Between each of the sharp projections thus formed, the edge of the wall of the calicle presents a curved indentation. Two of the specimens procured, expanded their soft parts when placed in sea-water. The inner margin of the disc round the elongated oral aperture, presents a regular series of dentations, corresponding with the septa, and is of a dark madder colour; the remainder of the disc is pale pink. The tentacles take origin directly from the septa. They are elongated and conical. Those of the primary and secondary septa are equal in dimensions, and along with the tertiary tentacles, which are somewhat shorter, but in the same line, are placed nearest the mouth, and at an equal distance from it. The tentacles of the fourth and fifth cycles are successively smaller and at successively greater distances from the mouth. Placed on either side of each tentacle of the fifth cycle, and again somewhat nearer the edge of the calicle, there are a pair of very small tentacles which have no septa developed in correspondence with them. There are thus four successive rows of tentacles, and the normal number is ninety-six. The tentacles are of a light red colour, and between their bases are stripes of yellowish red and light grey. This group belongs to the group Flabella sub-pedicellata of Milne-Edwards, and probably to that division in which the costæ are prominent and ridge like on the faces of the corallum, as well as on its lateral margins, but it differs from those described under this head by MilneEdwards, in that it has five cycles, the fifth being incomplete, and in other particulars which appear from the description given. A single living specimen of a coral referred by Mr. Moseley to the genus Ceratotrochus was obtained from this haul. The corallum is white. The base sub-pedicellate with a |