great developments to be recorded. We think that the inclusion of such subjects as photography (fifty-five pages) has helped to swell the volume to unnecessarily large proportions. The technics of a special branch such as this seems scarcely at home in its surroundings. We welcome in particular the articles of Drude on the nature of light, on the theory of light for transparent media at rest, for absorbing media, and, finally, for media in motion. The book is replete with references to original papers, and may be taken as being as complete a handbook for the professional reader as has yet appeared. GARDEN-BOTANY. Hortus Veitchii, a History of the Rise and Progress of the Nurseries of Messrs. James Veitch and Sons, together with an Account of the Botanical Collectors and Hybridists employed by them and a List of the more Remarkable of their Introductions. By James H. Veitch. Pp. 542; illustrated with fifty photogravure plates. (Chelsea: James Veitch and Sons, Ltd., 1906, for private circulation.) THIS of a HIS is one of the most sumptuous volumes which have ever emanated from a business house, but if it were simply a business publication it would claim no special notice in these columns. It is, in fact, a most important contribution to the history of horticulture during three-quarters century or more, and a valuable work of reference for the systematic botanist and the hybridist. It illustrates in a remarkable degree the service which the enterprise of a great commercial firm is capable of rendering, and in this case has rendered, to botanical science. As the author appropriately says:To the representatives seeking unknown plants at one period or another in almost every clime, fortune has not invariably been kind, but the work of such men as Thomas Lobb, William Lobb, the late John Gould Veitch, Charles Maries, and E. H. Wilson has been a gain in every way; whilst the efforts in hybridising and selecting of John Dominy, John Seden, V.M.H., and John Heal, V.M.H., have given a wider interest to all cultivators. With the history of the firm and its various members as given in the introduction to the present volume we are not here concerned, but we may indicate that it would furnish valuable data for Mr. Galton's science of eugenics. The biographical sketches of the twenty-two travellers employed by the firm are so interesting that we could have wished them longer. Whilst very many of the plants introduced into cultivation by the energy and zeal of these men have proved of first-rate importance from a gardener's point of view, as shown, amongst other things, by the fact that no fewer than 422 plates representing Veitchian introductions have been published in the Botanical Magazine under the editorship of the two Hookers and their successor, Sir William ThiseltonDyer, thousands of herbarium specimens have been the generously presented to national botanical establishments and to individual botanists engaged in the study of particular groups. When we come hybridists who have achieved success in Messrs. Veitch's nursery we are again disposed to regret that fuller details were not given, but in view of the magnitude of the book and the immensity of the task we are by no means surprised that the author has felt it necessary to give indications only. Certain it is that the students of hybridisation, variation, and heredity will find inexhaustible materials for study in the results obtained by Messrs. Veitch. It is a noteworthy fact that at the present time, when orchids are so popular, greater interest is felt in the hybrid "creations," in the production of which John Dominy was the pioneer, than in new introductions. When we read of a thousand pounds and more being paid for one of these specimens we can but regret that orchid lovers do not contribute more to encourage scientific research into the history and nature of the plants in which they take such keen interest. The list of species of orchids introduced by Messrs. Veitch occupies no fewer than forty-seven pages. A large proportion of these were described by Lindley, by Reichenbach, and subsequently by Rolfe, and short descriptions and historical notes are afforded in these pages. Orchid hybrids are treated in like manner, the particulars relating to them filling fifty-seven pages, exclusive of an appendix giving historical details, and occupying six pages of small type. The information here given will be of special value to those engaged in the study of hybridisation. to the section relating, to the Space will not allow us to do more than mention the sections relating to stove and greenhouse plants, to which eighty-three pages are devoted, to the various species and hybrids of Nepenthes, the ferns, the coniferous trees, the deciduous and evergreen trees and shrubs, the herbaceous plants, the bulbous plants, the Amaryllis, the Begonias, the greenhouse Rhododendrons, the Streptocarpus, and, lastly, the fruits and vegetables, all exclusively the result of the enterprise or of the skill of Messrs. Veitch and of their assistants. With such a vast amount of material it is evident that severe compression has had to be effected, but even so the record is a marvellous one. Happily an excellent index is provided. Throughout it is obvious that great pains have been taken in the preparation of the volume, the solid worth of which is enhanced by the excellent manner in which it has been produced. "expounded with such wealth of illustration and with so exhaustive a knowledge of the fundamental literature of the subject." This praise is, we think, fully deserved. Dr. Meldrum brings stern logic to bear on the question, and approaches his task with a grim earnestness which imparts an unintentional tinge of humour to his book. He is no respecter of persons, and he handles with some severity all those who, in his opinion, have been unfaithful to the facts. "The atom," says Dr. Meldrum, "in the modern theory of chemistry is a 'dependency of the molecule.'" "Avogadro's hypothesis being the fundamental hypothesis of chemistry, other doctrines concerning molecules and atoms are to be subordinated to it." "The atom can be defined with reference to the molecule; it is doubtful if any other definition is sufficient.' These quotations will perhaps suffice to indicate Dr. Meldrum's view. Dalton's hypothesis came first, but since 1858, when Cannizzaro appeared on the scene, Avogadro's hypothesis has been the fundamental one. We do not think that this can be seriously contested, taking the words strictly in the sense intended by Dr. Meldrum. At the same time there is surely some danger of a too pedantic insistence on this question of ratiocinative precedence." If we look upon the progress of chemistry, and not merely on its present state, it is hardly a crime to speak of that hypothesis as fundamental which has been the immediate cause of another that has ultimately proved more general, comprehensive, and fruitful, and whilst no doubt there has been some laxity on the part of chemical writers in their choice of words, the great fact that Dalton came first, and that without Dalton there is no reason to suppose there would have been an Avogadro's hypothesis, will still be regarded, we suspect, as a justification for some of the statements which Dr. Meldrum criticises so severely. In saying this we do not wish for a moment to underestimate the service which Dr. Meldrum has rendered by giving us this very searching and able review of the bases of modern chemical theory. A. S. Die radioaktiven Substanzen und die Theorie des Atomzerfalles. By Prof. Paul Gruner. Pp. 103. (Bern: A. Francke, 1906.) Price 1.60 marks. THIS little book of 100 pages, we learn from the preface, had its origin in courses of lectures delivered by the author at the University of Berne during the session 1904-5, and is designed to give a complete yet short review of the whole field covered by the title, including the most recent investigations. The subject is presented from the point of view of the disintegration theory, and the phenomena connected with the induced activity are treated at length. The physiological action of radio-active substances, and their existence in springs, &c., are not considered except in passing. The author is to be congratulated on having fully carried out his intention, and has succeeded in producing a very readable account of the subject from the physical standpoint, which is thoroughly up to date; but the value of the work would have been much enhanced by more diagrams. Only three are included, illustrating the decay and growth curves of the induced activity of radium, and not a single diagram of any experimental piece of apparatus is shown. Practically nothing is said of the methods of measurement in use in the laboratory, although perhaps this is as well in a subject of this kind, where a little knowledge is apt to be a dangerous thing. On the other hand, the author has contrived to compress within the one hundred pages of his book a surprising amount of the best of the most recent literature, and this makes us venture to express the hope that in a future edition the author will rely les on the existing compilations in dealing with the earlier researches, and will extend to the whole literture of the subject the same careful and first-hand consideration he has shown in dealing with the lates: researches. Of criticism or comment there is little or none, but there is evidence of considerable skill in the selection of the material whereby the most important researches secure prominent treatment. With the exception o the recent work emanating from Australia on the a rays, of which perhaps the full bearing has no been sufficiently brought out, the living branches the subject have been done full justice to. A refer ence to the parts dealing with the slow transformation products of radium, radio-thorium, the origin and ultimate product of radium, the work in German: and France on the production of helium from radius and actinium, and radio-tellurium and polonium shows that the author has included the best of the current work on the most important problems. F. S. Introduction to Astronomy. By Prof. Forest Riv Moulton. Pp. xviii+557. (New York: The Macmillan Company; London: Macmillan and Co Ltd., 1906.) Price 5s. net. STUDENTS of astronomy will find in Prof. Moulton's volume an excellent text-book which, by its lucidity and wealth of detail, will enable them to obtain fairly thorough grasp of their subject. After two chapters dealing with general outlines and definitions we find a very useful chapter on the constellations, with special paragraphs on the mor important stellar groups and simple methods o locating them. Four clearly printed maps, so bound that they open out flat when the book is opened, will be found very useful in the practical work which her and throughout the book is insisted upon as being essential. Telescopes, their evolution and various types, are then discussed, whilst the earth, its movements gravitation, and time are dealt with at some length in the four succeeding chapters. Chapters ix. to xii. deal with the moon, eclipse< the solar system as a whole and its individual members, respectively. The chapter on comets and meteors which follows leaves little, if anything at all to be said concerning the general phenomena and the historical apparitions of these bodies. Probably in no branch of astronomy have such rapid advances been made during recent years as in solar physics, and of the results obtained therefrom Prof. Moulton takes the fullest advantage in the forty-nine pages of description and discussion which he devotes to the sun in chapter xiv. Again, as a pioneer worker on the probable evolution of the solar system, he is seen to great advantage in the next chapter, where he describes and criticises the Laplacian hypothesis. explains the work of Sir George Darwin, and sum. marises the theories advanced by Prof. Chamberlin and himself. In the concluding chapter we have an epitome of our present knowledge concerning "the stars and nebulas," in which the facts and observations of most branches of sidereal astronomy are clearly stated and discussed. The numerous questions placed at the end of each chapter and the excellent and up-to-date illustrations add greatly to the value and interest of the volum as a text-book, W. E. R. LETTERS TO THE EDITOR. [The Editor does not hold himself responsible for opinions expressed by his correspondents. Neither can he undertake to return, or to correspond with the writers of, rejected manuscripts intended for this or any other part of NATURE. No notice is taken of anonymous communications.] The Recent Radium Controversy. I SHALL be obliged by your making the following correction on an accidental misstatement of mine, quoted by Mr. Soddy (p. 517, line 3 from foot of column one) in his very interesting article on The Recent Controversy on Radium," in your issue of September 20 (p. 516). In a letter to the Times, from which the quotation is correctly made by Mr. Soddy, I had written accidentally four instead of five. The corrected statement is that Prof. Rutherford had suggested that radium might be a compound of one atom of lead and five of helium. This is a suggestion wholly in harmony with chemical science. Rutherford is scientifically cautious in naming lead as possibly one of the ingredients of radium, but he names helium as demonstrated experimentally to be an ingredient, and considers five atoms as rendered somewhat probable by elaborate and important experimental investigations, of which he gives careful descriptions and very complete references in his book on " Radio-activity." Netherhall, Largs, September 21. Stress in Magnetised Iron. KELVIN. IN NATURE, August 2 (p. 317), I observe under the above title a letter from Dr. Shelford Bidwell re-opening a question discussed in your columns ten years ago. As the originator of the discussion I feel indisposed to let Dr. Bidwell's letter pass unnoticed. as and suppose them to be separated by air or by a non- 66 66 an In practice there are usually complications from free ends and want of symmetry. We may, at least theoretically, avoid such complications by taking some endless solid, the simplest being an anchor ring, preferably of small section but large aperture. Is there a hoop stress in such a ring when magnetised which did not exist prior to magnetisation, and, if so, what is its sign? If there is a hoop tension, then the case is so far analogous to that presented by a ring rotating about an axis through its centre perpendicular to the plane of its aperture. If we imagine a short element of the rotating ring bounded by planes through the axis, the tensions across the end faces will give an inwardly directed radial resultant which is balanced by the "centrifugal force. A stationary Saturn ring of continuous material, under the attraction of a planet at its centre, similarly gives a case of a compressive "hoop" stress; the pressures over terminal faces of an element give an outwardly directed resultant, balanced by the planet's attraction and that of the ring on itself. In the Saturnian as in the rotating In my first letter (NATURE, vol. iii., 1896, p. 269) I directed attention to the fact that certain writers, including Dr. Bidwell, Dr. J. A. Ewing, and Dr. More, had stated explicitly or implicitly that the material of a magnet is subjected to a longitudinal compressive stress approximating to B3/8 when H/B is small, whilst other authorities, including Kirchhoff and Prof. J. J. Thomson, postulated a tensional stress of like amount. I remarked on the apparent inconsistency, and explained the reasons which led me to regard the last-mentioned view as the more plausible. My letter led to others. Dr. Ewing explained that he had changed his views. He left it, however, uncertain whether he believed that no such stress as B2/8π exists in iron, or whether he took the view that tensional and compressive stresses both exist, but in adjacent por-ring (when reduced to a statical problem), the hoop stresses tions of the magnet. The latter view seems indicated by the illustration he advanced, viz. that of a man sitting in a clothes basket and pulling the handles. The medium in this case is obviously not free from stress, having a tensile stress in his arms and a corresponding compressive stress elsewhere. Prof. E. Taylor Jones wrote favouring a tensile stress, and referring to work by himself and Prof. Nagaoka on the subject. Prof. L. R. Wilberforce dwelt on the fact that the stress B2/87 most properly associated with Maxwell's name has its seat in a hypothetical ethereal medium, not in the material iron. Dr. Bidwell did not then give his views to the public, so far as I am aware. From his late letter I infer that they have remained unaltered since 1896. Dr. Bidwell advances illustrations to explain his ideas. His arguments, however, seem really to amount only to this, that if two masses of iron, whether bars or spheres, close to one another be capable of bodily movement (e.g. if they rest on a smooth table or be suspended by long threads), and have between them some compressible nonmagnetic medium (e.g. a finger), this interposed material will be squeezed if the iron becomes suddenly magnetic. This result is, however, equally consistent with either of the above theories; also it throws no light on the nature of the stress in the iron. If, however, we suppose as Dr. Bidwell ostensibly does -the two hypothetical masses of iron to be consecutive members of an infinitely long series, which seems the only hypothesis likely to represent the interior of a magnet, are really excited by a radial action. Is there anything equivalent to this in the magnetic problem? If there is no radial action there will naturally be a change of aperture, unless, like Dr. Bidwell, we suppose the magnetic material absolutely rigid." With change of aperture there will be change in the intermolecular distances, and so in the intermolecular forces. It would obviously be difficult to distinguish between the stresses due directly and those due indirectly to magnetisation. I might add that Dr. Bidwell's remarks on the "uniformly magnetised rod" divided transversely seem to me to confuse tensile with compressive stress. He deduces a stress from iron to air gap, which seems really a tension on the iron. If he supposes the two fragments of iron held so as to prevent them doing more than just touch, he will, I think, realise this. Again, his remarks in reference to his spherical model do not seem to draw a sufficiently clear distinction between stress and strain. rigid" body, if such an entity could be realised, might be under stress though exhibiting no strain. On the other hand, in an elastic body the signs even of the stress and strain in a given direction may differ. A During the ten years that have elapsed since the controversy began I have been too busily engaged in other matters to follow the developments of magnetic and electrical theory. I hope that the recognised leaders in these developments will not turn a deaf ear to Dr. Bidwell's appeals for further light. C. CHREE. September 15. The Rusting of Iron. DURING the past few months the study of the chemical changes involved in the rusting of iron has been coming to the fore. In 1888 Crum Brown pointed out that iron remained free from rust in an atmosphere of oxygen, carbon dioxide, and water vapour so long as liquid water was prevented from condensing on its surface. Whitney, in 1903, confirmed the opinion that liquid water alone had no effect on the metal at ordinary temperatures. No mention was made, however, of the purity of the iron used. Last year Dunstan, Jowett, and Goulding confirmed these results for polished iron plate (99.94 per cent. iron) in a series of carefully planned experiments. Since iron of such great purity as this is seldom used for commercial purposes, it seemed to me desirable to try the effect of water alone on different samples of varying qualities. Three such were chosen :-(1) cast iron from a piece of old piping; (2) wrought iron; (3) fairly pure iron (99.5 per cent.). The pieces were polished, and measured approximately 1 cm. long by 3 cm. broad and 0.2 cm. thick. They were dropped into flasks of boiling distilled water, and after five minutes the latter were closed with tightly-fitting india-rubber bungs, in the way indicated by Whitney. It was found that whilst the pure and wrought iron were unchanged, the cast iron invariably turned a shade darker in tint. The experiment was varied by employing thin glass tubes instead of flasks, and the surface of the metal was in some cases roughened with a coarse file. After the admission of the iron, the tubes were drawn out and finally sealed off. The results were invariably the same. I have kept these tubes for several months, but no further changes have taken place. This seems to indicate that, whilst neither warm nor cold water has any effect upon the purer forms of iron, they exert some slight action on the coarser cast iron. Many and various are the theories which have been suggested from time to time to account for the process of rusting. Crum Brown pointed out that carbon dioxide was necessary. This dissolved in the water and attacked the iron, forming ferrous carbonate, FeCO,, or perhaps the soluble ferrous hydrogen carbonate, FeH2(CO3)2. The hydrogen gas set free combined with any dissolved oxygen, forming water. The oxygen of the air would convert the ferrous hydrogen carbonate into rust, with the liberation of carbon dioxide. Thus a small amount of carbon dioxide in the presence of water and oxygen would be capable of converting an infinite amount of iron into rust. During the present year Moody has confirmed this theory by showing that if elaborate precautions are taken to remove every trace of carbon dioxide, pure iron (99.98 per cent.) may be kept for an indefinite time in the presence of air and liquid water without undergoing the slightest visible change. He has also directed attention to the fact that when a piece of pure iron is introduced into a dilute solution of distilled hydrogen peroxide the latter is decomposed slowly, evolving a steady stream of oxygen, whilst the iron is unchanged. This again demonstrates the fact that oxygen and water alone have no action on pure iron. I have repeated the experiments with hydrogen peroxide, using the different samples of iron already referred to. The peroxide was from Merck, and guaranteed to be pure. It was diluted to thirty times its volume with freshly-boiled distilled water. On introducing the iron, it was found that the pure sample remained perfectly bright, a slow stream of oxygen being evolved. After some hours an odd speck or two of rust appeared. No further alteration occurred even after the lapse of one or two weeks. The wrought iron decomposed the peroxide rather more rapidly, and the specks of rust were more numerous. The cast iron decomposed the peroxide with astonishing rapidity, and in a few minutes was covered with rust. This was, no doubt, due to catalytic action. We thus see that the purer the iron the less is the action of the peroxide upon it. Had such pure iron as that used by Moody been employed, I have no doubt my result would have exactly coincided with his. It is not impossible, therefore, that while carbon dioxide, oxygen, and water are essential for the rusting of pure iron, the last two alone may be sufficient to cause rust in the coarser forms, such as cast iron. J. NEWTON FRIEND. is as follows. About twenty years ago I read two pap by Lord Rayleigh and Prof. W. M. Hicks in which cert, in problems relating to the motion of a cylinder in a liar which possesses cyclic irrotational motion, were solved Both authors employed the old-fashioned method of relev lating the forces due to the pressure of the liquid; but I at once perceived that some form of Lagrange's equanier. must exist which would enable the problems to be solve! without introducing internal forces. I accordingly examines all the works on dynamics to which I had access, including Dr. Routh's treatises and Prof. J. J. Thomson's recentl published papers in the Phil. Trans., 1886 and 1887, bur without finding what I wanted. The necessary clue at length obtained by means of a theorem of Lord Keltin published in the Proc. Roy. Soc. Edin., vol. vii., p. ww (about 1872 or 1873), which enabled me to establish. th formula in question. Dr. Routh (Rigid Dynamics," pp. 319 and 320, fourt edition) has given some rather formidable determinants, Ix means of which it is conceivable that (1) might be deduced by a more or less lengthy analytical process; but in their present form I have never been able to make any use them. The procedure explained in §§ 418-420 could apparently be employed when the velocities which are 1 be eliminated are either unknown or would be inconvenient to introduce. A. B. BASSE). Fledborough Hall, Berks, September 21. Suspended Germination of Seeds. SOME years ago it was reported that charlock sed tu germinated upon the site of a Norman church in Ken: Is there any similar record of foxgloves awakening from a long sleep? Last February I removed an ancient wall circling the top of a very bare hill on a north country farm. We took out the large foundation stones. As the spring advanced, the site of the wall became carpeted with seedling foxgloves; if the cattle permit, a thick foxglov hedge will round the crown of the hill next year. There were no foxglove plants within several hundred yards, and even had there been roots there would be n seed in February. The wall was formerly the fence of an oak wood, which was felled and turned into pasture forty years ago. The seeds were unquestionably as ole as that date; but my own strong opinion is that they w right underneath the foundation stones of the wall, are had lain there ever since it was built. I examined the stre very carefully, and also noted that disturbance of the neighbouring turf, outside the site, did not produce ar foxglove crop. I believe that the oaks were planted ar* fenced by a man named Stephen Green between 1600 a** 1610. Another less pleasing instance occurred on the sa farm. I took some cartloads of turf and loam-top-spr from an old pasture traditionally called the " Barley Field -and spread it on another part of the grass; whereup there came up thousands of corn-weeds, such as fumitur and sun spurge, which were previously unknown in H. B. P pastures. Optical Illusions on Electric Fan. A REVOLVING electric fan with gilt blade is illumina'!* by the light from a window. When we look fixedly a the revolving face an irregular patch of greyish-purple colour appears on the yellowish ground. The patch sh an amoeba-like motion, and its size seems to increase with the speed of the fan. The border of the patch is colours* pale. In its centre a bright spot is often discerned. It we look at the fan after having closed or turned aside ret eyes for a while the patch has disappeared, and it takes a few seconds before it reappears. Several other experiments on illusion can be made cor veniently by means of the fan. If the blade be cow PTS with red papers and revolved slowly, a white paper looke at through the revolving face appears greenish, and T. TERAD greenish one greyish. Physical Laboratory, Tokyo, August 26. Aquatic-dwelling Weevils. I NATURE of September 6 there is a note (p. 472) on Dr. Nelson Annandale's papers on the fresh-water fauna India, ending with the words "an aquatic weevil, which, so far at any rate as habits are concerned, is altogether unique." If this sentence is intended to mean that water-dwelling weevils were previously unknown it Is incorrect. Mr. J. H. Keys and myself took specimens of the weevil Eubrychius velatus, Beck, from a pond near Plymouth in September, 1905, which were as thoroughly aquatic as any of the typical water-beetles (e.g. Dytiscidae), most of their time being spent in crawling under water on the leaves and stems of Myriophyllum. Fowler has an interesting note on this species, to the same effect, in his Coleoptera of the British Islands," vol. v., p. 373. Mr. Keys also states that Tanysphyrus lemnae, F., and the various species of Bagous are all more or less aquatic. E. E. LOWE. Museum and Art Gallery, Beaumont Park, Plymouth, September 11. Remarkable Rainbow Phenomena. THE letter of Mr. M. Spence in NATURE of September 20, describing a bifurcated rainbow, reminds me of a similar phenomenon which I saw some time during the winter of 1897-8. On that occasion the phenomenon was not so complete as that described by Mr. Spence, only the lefthand portion of the bow being visible. The arch rose from the horizon as a single column to a height of about ten degrees, and then bifurcated into two distinct branches, which, however, did not extend far from the join. As I was playing in a football match at the time it was impossible to study the effect at all closely; but, so far as I remember, the lower branch sprang out of the main regular bow, making with it an angle larger than that described by Mr. Spence. My incomplete observations were not alone of much value, but in confirmation of Mr. Spence's fuller description they may be worth recording now. Manchester University. GEORGE C. SIMPSON. SOME SCIENTIFIC CENTRES. NEARLY fifty years ago Sir John Brown, the famous engineer and steel manufacturer, with Dr. H. C. Sorby, the father of the introduction of the microscope for the examination of thin sections of rocks and of polished or polished and etched surfaces of iron and steel, attempted to establish in Sheffield a school of practical science; but as yet Britain held undisputed sway in the world of engineering and of metals; and the help of science, proffered by these far-seeing men, although just as desirable then as now, was rejected by such easy victors in the wars of commerce. The sum of 200l. was spent in advertising, with the result that only one student entered. Several years' perseverance never produced more than five students, so far as Dr. Sorby's memory serves him. Sixteen years later the added personal influence of such men as Mr. Mark Firth, Sir Frederick Mappin, Sir Henry Stephenson, and Mr. J. F. Moss failed to find a response, and although in 1879 Mr. Mark Firth founded Firth College to facilitate university extension work, it was not until 1883 that another special meeting was held, at which Dr. Sorby used the following pregnant words: "I do not see why we should not make the teaching of metallurgy a speciality of the town, nor why we should not make Sheffield the centre of metallurgical instruction." In 1885 the Sheffield Technical School was fairly launched in a separate building, but as a department of Firth College, with chairs of engineering and of metallurgy both held by the late Prof. W. H. Greenwood. Until 1889 the department of metallurgy was in connection with the Science and Art Department, and its work consisted of courses of lectures on fuel, refractory materials, iron, steel, and general metals, with assaying and experiments in a laboratory fitted with analytical benches, wind and muffle furnaces similar to those in the Royal School of Mines of that date. In 1889, Prof. Greenwood having resigned his chairs to undertake the management of the Birmingham Small Arms Factory, John Oliver Arnold was appointed to the chair of metallurgy which he holds to-day. He began at once to inaugurate revolutionary changes, the fundamental aims of which seemed to be: (1) to increase the science of the metals themselves, the art being then in great preponderance; (2) as the industries of the district were mainly of iron and steel, to pay special attention to these, assured that science could be as truly served and minds as fruitfully trained on metals of immediate interest to the district as on the wider range; and (3) to keep the ideal ahead of having available on a small scale, but by a manufacturing method as distinct from a laboratory method, examples of as many types of metallurgical processes as possible, so that the students might examine the whole course of each process from beginning to end in the comparative calm of an educational establishment. A start was made by erecting a two-hole crucible steel-melting furnace fully equipped as a small works, and differing only from the large works in the city in that theirs would consist of so many dozens or hundreds of holes of the same size. The effect on the attendance was electrical, and the available laboratory accommodation was at once completely filled. A difficulty here arose in that the Science and Art Department objected to the course, but a very simple solution was found in cutting the laboratory adrift from Government control, the public men supporting it guaranteeing against any resulting financial difficulty. It ought in justice to be said that in those days the department did sounder work for pure science than it seems to be the present fashion to acknowledge, although its influence on metallurgy in Sheffield was not good. The complete success of this first part enabled Prof. Arnold to induce the members of the governing committee to commence the more ambitious part of his scheme, though with some misgivings, and during the session 1890-91 the students had the rare privilege of following the erection of, as well as working, plant consisting of a 25 cwt. acid Siemens furnace, with gas producers and all necessary hydraulic power for lifts, a No. Stewart rapid cupola, foundry with drying stove for sand and "compo" moulds, and a falling weight test apparatus. As showing the curious features which sometimes govern a problem, although the No. cupola worked well it had soon to be replaced by a No. 1, as when the lining began to wear it was only with the utmost difficulty that even a temporary assistant of the staff could be obtained sufficiently attenuated to be able to effect the necessary repairs, and at any time inspection of the lining was somewhat of an acrobatic performance. A 50-ton Wicksteed mechanical testing machine for tensile, trans |