摘要:

THE proceedings of the Congress of Universities of the Commonwealth which was held in Cambridge last week were divided into a number of sessions on specific topics. Nevertheless, permeating the whole, there was the thought of the purpose of university education. Some recent pronouncements on this topic are thus of immediate interest. At the recent jubilee thanksgiving service of the University of Liverpool, the Archbishop of York, Dr. Cyril Garbett, urged that the noblest task of a university is to encourage in its students the disinterested and relentless search for truth. First and foremost, he said, a university exists for knowledge, and while earnestness in the search for truth is characteristic of what is best in the younger generation, those responsible for the work of a university should manifest a fearless and di ^interested love of truth in all its departments. This is the most effective safeguard against the attack upon freedom.The existence of a sufficient number of men and women who have been taught from their student days to value truth and to question and to criticize unproved assertions is the best defence against this danger, as has been shown in the United States when the academic freedom of the universities was threatened by security proceedings. That may well be the most important social function of the universities at the present time, and it may have determined Dr. J. B. Conant Js choice of the title "Education and Liberty" for his recent book on the role of the schools in a modern democracy. Dr. Conant took as his text the words Thomas Jefferson wrote to Washington in 1783: "It is an axiom in my mind that our liberty can never be safe but in the hands of the people themselves, and that, too, of the people with a degree of instruction"; and he discusses principally the changes in education at the school-level which are necessary in the United States to ensure the safety of freedom. Nevertheless, his theme is more related to that of the purpose of a university than would immediately be apparent to those unfamiliar with the overlap of the American college system with secondary education and university education in Great Britain. Dr. Conant's book is appropriately recalled here because, although he says little directly about the search for truth or the defence of freedom, he is concerned above all with making men and women competent to play their full part in the world to-day. This, said Dr. Garbett, is the second function of the university; and here, too, in the development of personality in its students, in encouraging the exercise of responsibility and initiative, which, if a democracy is to endure, must be possessed and used by the many and not by the few, the, university exercises a social function. Sir John Stopford, speaking later on the same day, emphasized the civic as well as the national and regional functions of the universities; and in referring recently to the work of the University Appointments Board at Manchester, suggested that the actual placing of graduates might well be less valuable than advisory work, in which the Board helped them to choose the appropriate discipline.That point was elaborated further by Sir Hector Hetherington, vice-chancellor of the University of Glasgow, in his Essex Hall Lecture, "The Social Function of the University", recently published. It was also put, but somewhat differently, by Lord Beveridge in writing on the main purpose of university life, as learning to use freedom. The extent to which a university succeeds in this largely determines that to which its graduates will succeed in taking their proper place in industry and in the public services, as well as in scholarship and the learned professions, and in breaking down inhibitions against their employment. Sir Hector Hetherington lays his main stress on education as the prime social function of a university. He recognizes, too, that there is also the communication of a culture and the discovery of new knowledge or research. Of the last, he observes that because real research or real scholarship is hard and punishing work, there is danger that the balance of interest of the ablest people may tilt too heavily in that direction. A university cannot be built if too many of its leading people come to regard teaching as second best. Also, the difference between research in the arts and in the sciences has been responsible for a change in the climate of opinion, and art disciplines, he thought, in changing their direction have moved onesidedly and a little lost their way. Also, while research is a superb and fortifying discipline, there is a tendency, he said, for it to be undertaken, both in the arts as well ae in the sciences, before the student has obtained the indispensable comprehensive grasp of the material of his subject.Sir Hector Hetherington's conception of the university's function of education is not narrow. It embraces the content as well as the communication of knowledge, the ways and habit of winning knowledge, and the judgments to be made in its assessment and use. To this he devotes the major part of his lecture, and it will be noted that, by and large, he confirms here much of what was said by Sir Richard Southwell in his Trueman Wood Lecture before the Royal Society of Arts on May 13. Sir Richard Southwell was dealing specifically with training in science and technology, and insisted that the structure of technological education in any country is, and should be, conditioned by the structure of its industry, and that this in turn is conditioned by its history. For this reason he was averse to rapid change, quoting Bacon's warning that "it were good . . . that men in their innovations would follow the example of Time itself". Sir Richard was opposed both to the lengthening of university courses and to the proposal to build a technological university on the lines of the Delft or Zurich Technical Colleges or the Massachusetts Institute of Technology. He did not deny the need for training to a high level in the specialized technologies of industry, but he insisted that the study of the application of science should take place where its development occurs-the vicinity of works or of great research institutions; application cannot be presented in vacuo. Sir Richard was anxious to safeguard the undergraduate against demands which threaten his wider education, and he visualized the universities as concerned primarily with the science which is pursued with the view of application, not directly with applications. At the undergraduate-level, the teaching should endeavour to instil a knowledge of the basic principles and the power to grasp essentials of a problem. At the postgraduate-level, however, the university should not only continue to supervise research but should also provide courses in the newer and harder parts of applicable science, and here he stressed the need for close contact and co-operation between the universities and the monotechnics and industry.Sir Hector Hetherington reaches similar views from rather a different angle. He seeks first to find the criteria which should determine the contribution of the university to the making of a professional man. Professional competence, he points out, calls for more than can be provided by any university; equally, the highest level of professional service calls for more than technical skill. Accordingly, the university's first contribution is to teach the professional man what he needs to know, and to teach him systematically, organically and thoroughly, so that he is master of it, and can use it to guide his actions in ways yet unforeseen. As the basis of intelligent participation in the affairs of his society, however, the professional man needs also to see his specialisms in their relationship to one another, as mutually sustaining elements in a living system, the place and claim of which in the larger context of human experience and reflexion he must to some extent understand. Thus, like Sir Richard Southwell, Sir Hector claims that the aim of university teaching should be to provide for all kinds of students, not a professional training but an education for professional service, a discipline which fits a man not only to meet the technical demands of his vocation, but also to share the concerns of a civilized society, to accept the enjoyments, the privileges and the responsibilities of the continuing life of his community. To meet this demand for wisdom as well as power, Sir Hector suggests first that the universities and their teaching staffs should take quite seriously the precept that their business is education and not training. Accordingly, the universities should accept as falling within their province only those professions the basic disciplinary requirements of which are capable of being the instruments of a genuinely educational process, of recognizable breadth and depth. They should admit all which meet this criterion, but no others. Like Sir Richard Southwell, he holds that if no more is wanted than techniques, it is not a matter for the university, although if genuine and systematic learning is involved, the university should, in principle, be ready to be concerned.Sir Hector Hetherington does not think that British universities have been at fault in this regard, nor does he think there is general disagreement with his second principle, that universities should accept only those students whose attainments give some assurance of their ability to sustain the discipline of a university education. Controversy has arisen rather over the application of this principle, and he pointed out that university requirements must be conceived not only in terms of what the universities think to be necessary, but also in terms of their effect upon the general working of the schools. Further, the duty lies upon the university system as a whole of seeking to provide places for all who are fit and who desire to enter, though not necessarily the places which the candidates profess a desire to occupy: the universities must try to keep their services in some kind of balance with effective demand. The third point made by Sir Hector relates to the formulation of university curricula. The primary requirement is that sovereign place at the university should be given to the educational rather than to the professional end. The professional intention prescribes the disciplines through which the educational end is to be achieved; but achievement is only possible if the content of every element in the programme and the mode of its presentation are weighed by an educational rather than by a professional measure. Sir Hector recognizes that this calls for a liberalizing, and a lightening of specialist courses, at the very moment when the growing complexity of professional services invites the further elaboration of specialist courses. None the less, it is inescapable if we accept the proposition that the university's primary objective is an educated man rather than an expert trained to the highest point of the moment's need.Sir Heotor pointed to some of the implications for the social life of the university, particularly the design and building of its organic life so as to provide for more abundant contact between student and staff in small groups and for the vital contact of minds; and in the ordering of courses and the scrutiny of the educational value of subjects admitted to a university curriculum, so that the university might realize its creative power to the full. While he said little on the university's function in the communication of culture, he said enough to bring to light the central issues as clearly as Sir Walter Moberly has done. A university is above all dedicated to the pursuit of truth, and there is no other way to truth than by untrammelled thinking, by following the argument wherever it may lead and by meeting the critical encounter of judgments other than one's own. Nor can an institution long endure if it has at its heart no more than a bundle of negations; and in his review of the social functions of the university, Sir Hector finds grounds for confidence for the future of the university and the society in which it exists, precisely because the conditions attached to its freedom of inquiry and teaching-responsibility and competence-have such a positive and constructive role in the society of to-day. Upon their exercise, as Dr. Garbett pointed out, the future of democracy largely depends; and Sir Hector concluded his lecture on a confident note that by patience and humility the universities would discharge their responsibility and provide society not merely with leadership but also with wisdom and vision.The Social Function of the University. By Sir Hector Hetherington. (Essex Hall Lecture, 1953.) Pp. 29. (London: Lindsey Press, 1953.) 2". net.

ISSN:0028-0836    

DOI:10.1038/172131a0

出版商:Nature Publishing Group    

年代:1953

数据来源: Nature

摘要:

IT seems a happy necessity that has finally extended the number of Dr. Ernest Guenther's volumes to six. In this respect, as in its total of well over a million words, the work now matches Gibbon's "Decline and Fall"; and in well-ordered presentment of the fruits of enormous study, it is not unqualified to sustain the comparison. Fittingly, therefore, recalling Gibbon's memorable introspection on the completion of his task, one may congratulate Dr. Guenther on the recovery of his freedom, sympathize with his sober melancholy in taking leave of an old and agreeable companion, and assure him as to the establishment of his fame. Admittedly, the scientist's achievement is less spectacularly single-handed than the historian's. As noted in the reviews of the earlier volumes1 and exemplified in Dr. Leo Goldblatt's monograph on the American turpentine industry in Vol. 6, Dr. Guenther has made way for able specialists in particular sections, constituting perhaps one-tenth of the whole. Nor can the scientific world be unmindful of a great debt to the firm of Fritzsche Brothers, without whose unstinted support the publication, could evidently not have been a practical possibility. Yet Gibbon's monomachy was a triumph exclusively of the library, while Dr. Guenther has refought his battles on the very ground, in the pleasant fields of Grasse and in regions much more remote: a valuable instance is his first-hand study, in Vol. 5, of the complex frac-tionation and grading of ylang-ylang oil as practised in the Madagascar islet of Nossi-Be. Before relinquishing the comparison, let it be said that Dr. Guenther's prose, while rightly refraining from the Roman majesty, is noticeably free from those infelicities to which the merely industrious compiler is so commonly prone.The two present volumes, continuing from Vols. 3 and 4 their account of individual essential oils, deal chiefly with the products of those plant families which, though low in the scale of quantitative output, gain importance from their commercial history and from their special characters as perfumes and flavours. Here, therefore, are most of the examples of the preparation of concretes and resinoids by non-distillation methods: processes as old as Homer, such as the extraction of rose oil into fatty pomades, or as recent as the extraction with such newer solvents as butane, by which the hitherto unattainable concrete of lily of the valley is now being prepared. Though the pure chemistry of the constituents of essential oils was formally dealt with in Vol. 2, Dr. Guenther has profited by his opportunity of recording subsequent advances in this field. To quote only a few examples from the present volumes, the monograph on Thuja plicata discusses the naturally occurring ct/cfoheptanone derivatives (tropolones) down to the synthesis of the three isomeric thujaplicins in 1951. The account of oil of hops includes a survey of recent investigations on the structure of oc-earyophyllene and its identity with humulene. Among other compounds for which these volumes record structural formulae proposed, revised or confirmed since the publication of Vol. 2 are cedrene, lanceol, (3-santalol, zingiberene, kessyl alcohol, luparol and the poly-ffcoetylenic compounds of the "matricaria-ester" type. Noteworthy also are the first records of the natural ooccurrence of a sulphoxide (sulphoraphene, in oil of Radish), the tricyclic terpene tricyclene in hemlock-spruce oil, and piperettine, a homologue of piperine, in oleoresin of pepper.Analytical procedures described in Vol. 1 have also been amended where necessary in view of later work: for example, the thiosulphate factor in ascaridole odetermination. One might wish, perhaps, for fuller?documentation of the statement that the halogen ^test (for synthetic benzaldehyde as opposed to natural oil of bitter almonds) has lost much of its importance owing to the production of the synthetic material in a higher state of purity. It is not clear whether this opinion takes account of very delicate chlorine determinations by the lamp method2, to which the book does not explicitly refer. Consideration of the six volumes as a whole may well prompt the reflexion that the essential oil industry has been singularly blessed in the production of such a book at such a juncture as the present. Even a few years ago, it would have been impossible to include much of the material descriptive of new and rationalized production techniques, which may be considered as prefiguring the industry's future; while in even a few years more, oblivion perhaps may begin to overtake much of its historic and romantic past-the buccaneers and galleons, and such strange contrasts as that between the sandalwood of Mysore, owned and accounted for to the last stick by a solicitous government, and the copaiba of Brazil, produced obscurely out of Amazon jungles by native woodsmen calling no man master. To students of either past or future, the book must be equally invaluable.In view of the progressive additions of new work, to which reference has already been made, a comprehensive index is a necessity for making the fullest use of the book. This is provided in the sixth volume, and extensive trials of its adequacy indicate it as an ending which may be said to crown even a maximum opus.

ISSN:0028-0836    

DOI:10.1038/172133a0

出版商:Nature Publishing Group    

年代:1953

数据来源: Nature

摘要:

WE have now to consider more especially a long VV and barren period, which intervened between the scientific activity of ancient Greece, and that of modern Europe; and which we may therefore call the Stationary Period of Science. ..." The quotation from the "Dunciad" which precedes the above passage indicates the probable source of William Whewell's judgment on the science of the Middle Ages. The almost universal self-complacency of the eighteenth century was expressed with such linguistic facility as to create a mist between later scholars and medieval ideas, which despite the wind of criticism of Duhem, Haskins and many others has been slow to clear. Indeed, even in the recent literature of Great Britain it would not be difficult to find judgments differing little from that of Whewell. Dr. A. C. Crombie's book is therefore doubly welcome; for, providing as it does the first reasonably complete survey of the period within a moderate compass, it will be an invaluable work of reference for the medieval historian and a richly rewarding study for those men of science for whom last year's books are not already out of date. The plan of the book is based on the sound assumption that to do justice to the history of an epoch we must first make sure that we understand the nature of the questions to which answers were then being sought; for only by so doing can we make sense of the answers-or what the inquirers of far-off days thought were answers. To achieve this task, Dr. Crombie reviews in turn the science of Western Christendom up to the renaissance of the twelfth century; the subsequent reception of Grseco-Arabic science; and the flowering of scientific thought born of this fertilizing influence. Stepping back from the stream of history, he surveys the relations of science and 'technics' throughout the whole medieval period, and concludes his review of that period by a careful study of the gradual undermining of the Aristotelian authoritarianism (in this sense, as Whitehead reminded us, Aristotle was not an Aristotelian) within the medieval period itself. The last section of the book-running to well over a hundred pages-is devoted to the revolution in scientific thought during the sixteenth and seventeenth centuries.It is impossible within the compass of this notice to do justice to the wealth of evidence provided in support of Dr. Crombie's implicit claim that whatever faults there may have been in medieval thought -and he does not deny that there were some-it was certainly not 'stationary'. The twenty pages devoted to bibliography include references to general works in the history of science, more detailed studies of special fields, and a representative selection from the periodical literature in English, French and German. These include numerous modern texts of original medieval sources. The iconographical sources-so important in this period-are represented by twelve plates and fifty text figures: these are admirably selected, and many are from manuscript sources not readily accessible. Something, however, has gone wrong with the legend to Fig. 1 (p. 53), where the Latin would have shocked even the 'Scholastici barbari', and the cosmology represented is 'Aristotle's' only in an Aristotelian sense. Nor, if the examples on p. 138 are a fair sample, is it at all clear what Dr. Crombie means by calling them "excellent": the heart is much too small and placed (conventionally) on the left side of the body, while the representations of the gut and skeleton perhaps bear a slight resemblance to a frog's but none at all to a man's. In the admirably generous and discrete documentation (for a full apparatus of detailed references would be a burden to that 'general reader' whose perusal of the book is so much to be desired) I have found none but comparatively trivial mistakes; but "Principia Mathematica" (1687, not 1686) has an unfamiliar ring in connexion with Newton. One concession to the 'general reader'-the use of the term 'doctor' as a synonym for 'medical man'-is, I suggest, one which, especially during the medieval period, might well have been eschewed. Not every chemist (nor every mathematician) will be flattered by Dr. Crombie's assertion that "chem- istry, like physics, finally set out on its course of being reduced to a department of mathematics"; and at least one reader sees no reason to revise his opinion that, apart from a few exceptional men like Petrus Peregrinus and Theodoric of Freiberg, the medieval thinkers entirely misconceived, as had the Greeks before them, the true nature of experiment. The absence of detailed accounts of the disposal of apparatus and of the control of the sources of error seems to mo sufficient proof that it was regarded merely as a means of verification, in striking contrast to, say, Newton's first letter on the "celebrated phaenomena of colours". But if here and there Dr. Crombie's enthusiasm may have outrun his discretion, his book is one which will set a standard for a long time to come. Its publication has removed for ever any excuse there may have been for ignorance of medieval scientific thought.

ISSN:0028-0836    

DOI:10.1038/172134a0

出版商:Nature Publishing Group    

年代:1953

数据来源: Nature

摘要:

THE development, use and maintenance of grass^ A land in Britain is a matter of vital national importance-an importance which is becoming more apparent with each pronouncement concerning the national economic position. Faced with the imperative necessity of increasing agricultural production, it is to the grassland that one must look in the main for greater supplies of meat, milk and dairy produce. What is more, grassland represents a vital factor in maintaining soil fertility as well as a means of actually building up fertility, thereby raising the level of corn and root-crop production which is so essential to survival. The potential of production from grassland rightly cultivated is immense, and the picture is most ably portrayed by Dr. William Davies in his new book, "The Grass Crop", for he himself has been concerned with this crop both in the sphere of research as well as advisory work among farmers for more than thirty years. Allied to his own work on the subject, Dr. Davies, as director of the Grassland Research Station, is in close contact with all the problems of the subject and has widened his canvas by first-hand study in many countries abroad. As a result he has been able to present not only a skilful, scholarly treatise of the subject but also one which will have lasting value to farmers and students alike.In the early chapters, the historical and ecological aspects of grassland are presented, and Dr. Davies has been successful in weaving into this section much of the philosophy of modern grassland farming. As he so rightly points out, grassland agronomy must have an ecological approach but one not confined to plant ecology, for due heed must be given to both the animal consuming the herbage and the soils producing it. There is, too, the complicating factor of climate which determines the growth of the crop as well as the manner in which it shall be used by the farmer. Thus, the approach to the subject has very wisely been that of the trinity of soil, sward and animal. Advocacy of the ley system of farming is emphatic and well reasoned, and the target is set at twelve million acres while at the same time retaining the present acreage of field-crops in Britain. The achievement of this goal would enable the sheep population to be doubled and the cattle population increased by more than a third above the 1951 level. But what is more, the attainment of such standards would act as a stimulant to the whole of the agricultural industry. One has only to travel through those counties where the ley is regarded as the pivot of the rotation to realize the salutary effect upon crop production as a whole of the securing of first-class leys.To accept the principles of ley farming is one thing -to put them into operation is vastly more difficult. So Dr. Davies gives skilled attention to the vital problems of choice of seeds mixture, the establishment of the ley and the influence of the grazing animal on the productivity of the ley as such. A chapter is devoted to a detailed description of the characteristics and agricultural value of the different species and strains of grasses and clovers, and there are chapters on lucerne and the controversial subject of herbs. Seed production, which offers not only a useful additional source of income for many British farmers but is also of vital economic consequence traditionally, rightly merits a special chapter. Particularly valuable are the chapters dealing with permanent grassland and the development of the marginal and hill lands of the country, for it is here that the untapped potential lies and where criticism ' can so rightly be directed at the. conditions found to-day. The book is completed with an excellent detailed bibliography, covering all aspects of the subject, and also a useful index. It is to be hoped it will have the wide reading public it so richly merits, for apart from the farmers and students for whom it is specifically written, all with an interest in British farmlands, be they geographers, historians or simply lovers of the countryside, will find fascinating and really worthwhile reading in its pages.

ISSN:0028-0836    

DOI:10.1038/172135a0

出版商:Nature Publishing Group    

年代:1953

数据来源: Nature

摘要:

SINCE Crum-Brown and Fraser in 1869 ventured to present the relationship between the chemical constitution of a drug (C) and its pharmacological activity (9) in the form of a pseudo-mathematical equation 9 = f{G), numerous attempts have been made to verify this relatively simple expression. That these efforts to find a rational basis for drug action have not resulted in overwhelming success is due to various reasons: for example, the meaning of (7, the chemical constitution, has often been accepted with superficiality as the two-dimensional formulae used in chemists' notebooks and not as an integrated collection of all the finer points of physical and chemical properties of the compounds under consideration; differences in the mechanism of action between drugs achieving the same end-effects have been frequently ignored, and the existence of receptor molecules, possessing, like the drugs, specificity of structure and reactivity, has rarely been taken into account; differences in the degree of accuracy between the measurements of biological effects and certain physical-chemical characteristics have been overlooked in many cases. It is therefore not surprising that, during the past thirty years or so, most of the major advances in the field of biologically active substances have been made by trial and error and by fortuitous discoveries. Yet, here and there, groups of therapeutics were found which were more amenable to a rational treatment, and the emergence of the theory of antimetabolite action has given renewed impetus to the slowly moving searches. But there still remains the necessity for more and more data of biochemical, physicochemical and biological observations, the last-named as quantitative in nature as possible.To provide such data the United States National Research Council founded in 1946 the Chemical-Biological Coordination Center. With lively optimism, so characteristic of many American undertakings, this body has developed procedures for the collection of data sheets, the preparation of card files and the use of chemical and biological codes. From time to time, accumulated results are published in the form of booklets. True, the chemical data are sometimes scanty and physical-electronic properties more than often missing. The biological results suffer from the fact that they belong to the plus-minus variety; but matters have progressed sufficiently to warrant, in May 1950, the arrangement of the first symposium on simply, perhaps over-simply, expressed "Chemical-Biological Correlation". The lectures and discussions were published during 1951, unpretentiously in varitype print, giving to everyone interested in the subject the chance to see for themselves how matters stand. There are a number of most stimulating contributions, such as that by Schubert on the effect of drugs on physiologically active thiol systems, and by Friedman on the influence of isosteric replacements upon biological activity. Others, experts in various special fields, like Doak and Eagle on arsenosobenzenes, Norman and Weintraub on plant growth-regulators, Lands on sympathomimetics, and Horsfall et at. on fungicides, have chosen a defined group of closely related substances to prove their case. Two lectures on antihistamines and anti-thyroids were used to demonstrate the procedures and the systems introduced by the Center and separately explained by its director, Dr. Kirner, and Drs. Beard and Geer. Two panels were discussing antimalarials and antimetabolites, carcinogenesis and cancer therapy. With regard to the first, one could quote F. L. Rose's statement on the occasion of his Tilden Lecture, "A Chemotherapeutic Search in Retrospect": "... the use of the 'working hypothesis' concept based on observation and the intelligent development of leads . . . must constitute the foundation for speculative research in this field for a long time to come". As to the wide and complex subject of antimetabolites, carcinogens and carcino-lytic substances, only the antimetabolites seem to obey certain rules. The rationalization of conditions of cytotoxic compounds is more than ever waiting for the discovery of their true mechanism of action. But this problem, although a very thorny one, and those problems connected with drugs where the mode of action has been more fully elucidated, may yield sooner than expected at present if the attempts at producing and then collecting all pertinent data are vigorously continued; for, as Hales said at the beginning of the eighteenth century, "hardly do we guess aright at the things that are upon earth, and with labour do we find the things that are before us".

ISSN:0028-0836    

DOI:10.1038/172136a0

出版商:Nature Publishing Group    

年代:1953

数据来源: Nature

摘要:

THE object of this tract is to enable mathe-X maticians who are not specialists in the theory of numbers to learn some of its non-elementary results and methods without too great an effort. It assumes no previous knowledge of the subject beyond what is given in Hardy and Wright's "An Introduction to the Theory of Numbers". The tract consists of three chapters. The first deals with Riemann's zeta function and a refinement of the asymptotic formula for the number of primes not exceeding a given integer. The second chapter deals with primes in arithmetical progression, using Dirichlet's L functions, with many theorems on characters. The third chapter deals with the representation of an odd number as a sum of three primes, using the methods of Hardy and Littlewood, and an extension of them by Vinogradoff. The tract concludes with a list of ninety-six theorems and formulae for reference, and with a very short index. The author seems to have done his best to simplify a difficult subject, but those new to it may be surprised at the complexity of the methods necessary to establish a simple result.

ISSN:0028-0836    

DOI:10.1038/172137d0

出版商:Nature Publishing Group    

年代:1953

数据来源: Nature

摘要:

ON February 6, 1953, a meeting, arranged by the Physical Society, was held in the Department of Meteorology, Imperial College of Science and Technology, London, under the chairmanship of Mr. J. A. Ratcliffe, to discuss the physics of the upper atmosphere. The present article describes, from the meteorologist's point of view, the major problem raised at the meeting. Before any attempt was made to theorize about the motion of the air at great heights, it was necessary to sample its physical condition. Though it was possible to explain the propagation of the Krakatoa air-wave on the assumption that above the troposphere lay a stratosphere of uniform temperature up to infinity, the reflexion of explosion waves from a height of about 30 km. clearly indicated the existence of a layer in which the temperature increased upwards. This layer is now known to be kept at its high temperature-in places warmer than the air at the ground-by the absorption of a large part of the ultra-violet radiation from the sun by ozone, which is itself produced by this radiation. The ozone dissociates only slowly and can therefore be used as an indicator of the motion of the air at those heights. For example, if a column of air at the ozone levels is elongated vertically the absorption of the ultra-violet is increased: this happens over extra-tropical depressions. Again, the accumulation of ozone over the winter pole, where it is certainly not produced, shows that there is a persistent motion towards that region at the ozone levels. Measurements of absorption by ozone are fairly simple to make, and by comparing the intensity of absorption with the intensity of a nearby wave-length that is not absorbed by ozone when light from the zenith is observed at a large number of times around sunset, a knowledge of the levels from which the scattered light originates may enable an estimate of the vertical distribution of ozone to be made as a routine1.The temperature in the ozone layers is a maximum at about 50 km., and above this level it decreases veiy much as it does in the troposphere, and a minimum of temperature is reached in the region of 80 km. It has been possible2 to obtain reflexions of radio waves from the .EMayer, not far above this level, which show that the reflecting layer is not uniform. The non-uniformities are found to move horizontally with velocities of the order of 5-50 m./sec. Similar movements, often with much greater velocities, in one case as large as 1,000 m./sec, have been observed in the non-uniformities of the .F-layer; but at those levels (around 200 km.) the motion is dominated by electromagnetic and viscous forces and little guidance can be obtained from ordinary dynamical meteorology about the causes of such movements. At levels below 120 km., however, those forces are not predominant in producing the motion of the air, which therefore moves under much the same influences as the air with which meteorologists ordinarily deal-below 30 km. It is of interest to discuss what meteorologists can say about the motion of the air in and below the E-layer. Since this layer lies just above the ozone layer, we must first discuss the condition of that layer. Dynamical Influence of the Upper AtmosphereSome deductions can be made from observations made at the ground. The semidiurnal pressure oscillation3 greatly exceeds the equilibrium tide value, and resonance was suggested by Kelvin as the explanation. If the driving force is gravitational, the resonance must be so selective that the lunar tide is not similarly amplified. Two difficulties arise: first, resonance seems to be an incredible fluke; and second, meteorologists are unable to accept that the resonance is so selective. Holmberg4 has explained how the fluke could have come about. He reminds readers that the pressure surge in the air actually drives the earth round and so overcomes dissipation in the ocean tides and other retarding forces. When, during its evolution to its present state, the rotation was reduced to the speed at which resonance occurred, further slowing down was prevented by this mechanism. The resonance is therefore to be expected and is no more improbable than the monthly rotation of the moon on its own axis, for example. The second objection is based on the knowledge that the Krakatoa air-wave was greatly distorted by the wind systems in one passage around the earth. The damping is therefore very large for this cause, and the resonance is unlikely to be selective enough to exclude amplification of a larger lunar tide. But we may follow Kelvin and suppose that most of the energy is derived, not from tidal forces but from the temperature oscillations, in which the semi-diurnal component is large. The diurnal variation in amount of cloud and rainfall accentuates the temperature variations, and in many parts of the world there is a nocturnal as well as an afternoon maximum.The 12-hr, resonant period is not the only possible one, and the 10-J-hr. period, if it occurred, would be of much larger amplitude in the troposphere relative to its amplitude in the ozonosphere than the 12-hr, one. Since the energy is mostly put in in the troposphere, why did not the earth cease to slow down when its rotation period was reduced to 21 hr.? Perhaps it was never as small; or if it was, it was at a time when the temperature of the troposphere was much greater. But among other explanations is the possibility that most of the energy is put in in the ozonosphere, where the diurnal temperature variations must therefore be large. The point here is that the upper half of the ozonosphere probably behaves in many ways like the troposphere, and this argument reinforces belief that it does. Further support is gained from the study of mother-of-pearl clouds. These are thought to form in the lower part of the ozonosphere in the crests of waves produced by the flow of a strong wind-current over a mountain range. In order that such wave motion should occur, the condition of the air at higher levels must be suitable, and one possibility is that the upper half of the ozonosphere is in neutral static equilibrium, that is to say, it is thoroughly stirred by convection currents-as is the troposphere.Ordinary meteorological observations indicate no influence of the ozonosphere on the weather systems except in a rather indirect way. For example, Palmer5 suggests that during a solar flare considerable ultraviolet radiation penetrates the ozonosphere and warms the lower stratosphere, with important consequences to the weather. No direct dynamical influence on weather systems other than the two just mentioned has been inferred. Dynamical Properties of the Upper OzonosphereIf the motion in the troposphere were the same as the mean motion, it would be unstable. The nature of the instability, which can be studied theoretically, and which we will refer to here as the 'cyclone type', gives a clue to the mechanisms operating in the disturbances which are the departures of the actual motion from the mean motion, and there is reason for believing that these operate in a similar manner in the upper ozonosphere. But the results would be somewhat different. In the first place, there is no rigid boundary, and this would make it less likely that sharp surfaces of discontinuity of temperature and velocity, known as 'fronts' in the troposphere, would be generated. Another effect due to the earth's surface is that the diurnal variations of temperature occur mainly over the land, which forms only a small part of it. Heat is communicated to the air by convection currents from the surface. This convection goes on day and night over the oceans, while in the ozonosphere the heat is absorbed over a great depth of air-effectively perhaps 20 km. -and is all taken in during the hours of sunshine. It is to be expected, therefore, that the convection currents, which shall for convenience be called the 'cumulus type', would be on a much larger scale, geometrically, the largest being indistinguishable from the cyclones and anticyclones generated by the other mechanisms, while diurnal variations (in which are included the semi-diurnal) would be much more in evidence.A static picture of the state of the atmosphere at these levels has been usually presented. In the troposphere and lower stratosphere, we know that the variations are very great and that at any one moment the temperature is very different from its average value. There is a continual exchange of air between the troposphere and the stratosphere by means of the disturbances of the cyclone and anticyclone type, although ordinary convection is restricted to the troposphere. Any vertical temperature gradients in the ozonosphere that may be measured cannot be taken as representative because there is no single state to represent. There is almost certainly a vigorous exchange of air, of a type that is hybrid between the towering cumulus and the cyclone, between the ozonosphere and the levels of the 22-layer by means of convection currents, and these would presumably produce variations in the ionization concentration in the i-layer. Meteorologists cannot at present be expected to develop the mathematics of these convection currents, for the theory of the disturbances we can readily observe in the troposphere is very rudimentary and observations are completely lacking in the ozonosphere. It is here that the observations on the size, diurnal variation and movements of the irregularities of ionization can help, for if they are due to these motions a scale can be set for them and we can begin to theorize.Interpretation of Observations Now that a fairly long series of observations on the movement of the irregularities is being accumulated, it is worth while to do more than speculate about the meaning of these movements. At first they were interpreted as winds, that is, bulk movements of the air as a whole. The daily variations first found at Cambridge have not been exactly repeated either at Washington or at Cambridge in another season, and obviously more observations are required before we can decide whether the supposition that the movements are winds is reasonable. We know that the diurnal influences are very strong; but a regular daily cycle of wind reversal is not what meteorologists would expect on the basis of observation of the air lower down, except that the semidiurnal oscillation would be large at these levels; but that would not interfere with the convection and other circulations. This does not mean that the movements are not winds, but that we cannot easily be satisfied that they are; no meteorologist would be dogmatic at present.The possibility that they represent some kind of inertial gravity wave motion transmitted through the air must be ruled out until an energy source for the wave motion has at least been suggested. Because of the enormous variety in wave-lengths and velocities that could be transmitted by the air, it is possible to 'explain' almost any motion in terms of waves so long as the wind velocity is not known, because the wave velocities depend so much on the wind structure. If the movements are not of air but of ionization density, a cause for the non-uniformity may nevertheless be sought in the inhomogeneity of the air. The atmosphere is certainly well stirred up to 100 km. and probably higher by ordinary meteorological mechanisms; but since convection is the mechanism for the stirring, the inhomogeneities are on the scale of the convection. The inhomogeneities are mainly of ozone, water vapour and temperature (that is, density); whether these can produce variations of ionization of the observed kind is not for the meteorologist to say. When the irregularities have been created by air movements, they may yet follow a path dictated primarily by electromagnetic forces.At much greater heights, in the .F-layer, irregularities also appear and are similar in many ways; but the medium, being so rare and so highly ionized, does not behave like the fluid with which meteorologists ordinarily deal. ConclusionObservations, direct and indirect, indicate a mean profile of temperature with a maximum around 50 km. and a minimum around 80 km. In many respects the dynamical properties of the layer between are likely to be similar to those of the troposphere; but there are significant differences, the chief of which are the dominance of diurnal variations and the greater size of the convection elements. The actual temperature at any place and time probably differs greatly from the average, and it is the variations which are associated with the important dynamical processes. At present, the only frequent observations being collected are the movements of the irregularities in the7-layer; and meteorologists hope that there is a connexion between them and air movements, however indirect, so that they will throw some light on the scale of the motion.

ISSN:0028-0836    

DOI:10.1038/172138a0

出版商:Nature Publishing Group    

年代:1953

数据来源: Nature

摘要:

ON the advice of the Agricultural .Research Council, the Minister of Agriculture is founding an independent Agricultural Research Institute to promote research on the cultivation of glasshouse crops and mushrooms and of bulbs, flowers and shrubs grown commercially in the open. The announcement marks another step in the evolution of the Agricultural Research Service, and there is interesting history behind it (see also Nature of July 18, p. 89). Forty years ago a group of nursery growers in the Lea Valley north of London were alarmed by the losses caused by pests and diseases on glasshouse crops and realized the need for research to be directed upon means of control. They formed the Nursery and Market Garden Industries' Development Society, Ltd., and, assisted by grants from the Ministry of Agriculture and from three local county councils, started a small experimental centre at Cheshunt.The venture quickly proved its value, and acquired a reputation more than local. In 1923 the Ministry of Agriculture increased its grant to allow for increase of staff and more laboratory accommodation, on condition that the centre should extend its services beyond the Lea Valley to the glasshouse industry of the whole of Britain. The Experimental and Research Station, Cheshunt, then began to take the form it has to-day. The field of investigation widened to include studies of glasshouse soils with particular reference to the effects of partial sterilization by steaming or other methods, the physiology of glasshouse crops, and new techniques in glasshouse practice generally. The contributions of the Station, under the direction of Dr. W. F. Bewley, to increased production under glass have been set out in a series of annual reports, of which thirty-seven have been published. When, after the Second World War, the National Agricultural Advisory Service was established, the Station, like other research institutes of similar origins, found itself relieved of direct advisory responsibilities to growers and freer to concentrate on the fundamental scientific questions that underlie the day-to-day practical problems of the industry. Tt was, however, not equipped to take full advantage of the change in emphasis.By this time the facilities at Cheshunt had become inadequate for a national glasshouse research station. The Lea Valley had changed in character; the site was hemmed in by urban development and critical work was handicapped by the atmospheric pollution associated with the growth of Greater London. A move that would have been inevitable in any event was made more urgent by damage sustained by the Station during the War, which left the experimental glasshouses in bad condition. A group appointed jointly by the Agricultural Research Council and the Agricultural Improvement Council to survey the post-war needs of research in the various branches of horticulture recommended that a new site should be found for glasshouse research, and that the opportunity should be taken to couple with it research into other commercial nursery crops for which no central facilities have hitherto existed, especially flowers grown out of doors.A long search began for a site combining all the necessary features, one of which is proximity to an important local glasshouse industry. It ended recently with the acquisition of a hundred acres of land at Toddington, near Littlehampton, Sussex. Here the new Institute will begin its work with staff and apparatus transferred from Cheshunt and will have room to extend the Cheshunt programme in several directions. The better light conditions for which the Worthing district is famous will make possible many studies of plant growth under glass on a scale hitherto impracticable. There is, for example, a promising field in the exact definition of the light and temperature requirements of glasshouse crops, which are known to vary between different varieties and at different stages of development for each variety. With facilities for critical experiments, the new Institute will be able to collaborate more effectively with the National Institute of Agricultural Engineering, which is working on glasshouse design and the control of glasshouse climate and so seeking to find the means of meeting the requirements of plants economically.In developing new lines of inquiry, the Institute will not abandon the old, for the war against pests and diseases under glass still remains of major importance, and the study of new weapons and tactics deserves the better facilities that will be provided.

ISSN:0028-0836    

DOI:10.1038/172140a0

出版商:Nature Publishing Group    

年代:1953

数据来源: Nature

摘要:

WITH the object of commemorating the name and work of Sir Jack Drummond, who, together with Lady Drummond and their daughter Elizabeth Anne, were murdered on August 4 (see Nature, 170, 229, 401; 1952), a Committee has been formed under the chairmanship of Lord Woolton, and over Lord Woolton's name an appeal has been issued. The members of the Committee are Lord Horder and Prof. E. C. Dodds, representing medicine; Sir Harold Himsworth, secretary of the Medical Research Council; Sir William Slater, secretary of the Agricultural Research Council; Dr. Norman Wright, of the Ministry of Food; Profs. A. C. Chibnall, G. F. Marrian and F. G. Young, representing biochemistry; Mr. Leonard Anderson, Dr. H. J. Channon, Sir Harry Jephcott and Mr. Wilfred Vernon, representing industry; and Dr. If or Evans, provost of University College, London. The Committee considers that the most suitable memorial would be an endowed Drummond Research Fellowship dealing with Sir Jack's main interest, namely, nutrition. A fund of about25,000 is required, which will be administered by a body of university trustees, and the Fellowship will be tenable at any university or appropriate research institute. Subscriptions, whether by gift or covenant, should be addressed to the Drummond Memorial Fund, c/o Westminster Bank, Ltd., 154 Harley Street, London, W.1.

ISSN:0028-0836    

DOI:10.1038/172141a0

出版商:Nature Publishing Group    

年代:1953

数据来源: Nature

摘要:

AN Irish National Committee for Geodesy and Geophysics was established in 1952 with headquarters at 44 Upper O'Connell Street, Dublin. The Committee was established in accordance with the recommendation of the International Union of Geodesy and Geophysics, of which Ireland, through the Department of Industry and Ccmmerce, has been a member since 1939. The Minister for Industry and Commerce, Mr. Sean F. Lemass, appointed Mr. J. C. B. MacCarthy, of the Department of Industry and Commerce, to be chairman of the Committee. Represented on the Committee by one member, whose name is given in brackets, are the following institutions: Irish Meteorological Service (Dr. M. Doporto); Royal Irish Academy (Prof. J. J. Dowling); Seismological Observatory, Rathfarnham Castle (Rev. R. E. Ingram, 8.J.); University College, Cork (Prof. J. J. McHenry); St. Patrick's College, Maynooth (Rev. P. J. McLaughlin); Ordnance Survey (Lieut.-Col. J. E. Nolan); University College, Dublin (Dr. P. J. Nolan); Geological Survey (Mr. M. V. O'Brien, director of the Survey); University College, Galway (Prof. CO. Brolchain); Department of Agriculture (Mr. S. O. Meallain); Dublin Institute for Advanced Studies (Prof. L. W. Pollak); Trinity College, Dublin (Prof. J. H. J. Poole). The Committee meets about four times a year, and the matters which have so far engaged the attention of the Committee include hydrography, the Irish bibliography for hydrology, geodetic levelling and methods of accurate computation of mean sea-level for Ireland. The means by which the Committee can most effectively discharge its functions have been under consideration, and the Committee or individual members thereof will welcome communications from scientific bodies or persons interested in any of the branches of science covered by the International Union.

ISSN:0028-0836    

DOI:10.1038/172142b0

出版商:Nature Publishing Group    

年代:1953

数据来源: Nature