Scholarly article on topic 'Introduction to the Theory of Spectacles'

Introduction to the Theory of Spectacles Academic research paper on "Art (arts, history of arts, performing arts, music)"

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Academic research paper on topic "Introduction to the Theory of Spectacles"

258

NA TURE

[February 21, 1925

is a sufficient indication of its comprehensiveness and trustworthiness, two qualities which in an undertaking of this kind are absolutely indispensable. Unless one can be perfectly certain that a bibliography is full and accurate, one always has the uneasy feeling that something of importance may have been overlooked, and there is nothing more depressing.

Parts 1 and 3 of the Catalogue—all that are published so far—deal respectively with the Greek alchemical manuscripts in Paris and those of the British Isles. The first part, which is the work of M. Henri Lebegue, includes also a description of the MSS. of the Koeranides by Mdlle. M. Delcourt, who provides, in addition, comprehensive indices to the whole volume. On the Koeranides or Kiranides—a work on the virtues of plants and animals—reference may be made to Thorn-dike's " History of Magic and Experimental Science," 1923, ii. ch. xlvi., and to Ruelle's " Lapidaires grecs," Paris, 1898: The Greek alchemical manuscripts at Paris are 19 in number. They are carefully described folio by folio, in such a way that a good idea is given of the whole contents. When they have been edited, references are given to the edition. Scholars, therefore, who desire information on the MSS. will find, ready to hand, all that is necessary to enable them to form a judgment.

The third part, which deals with the manuscripts of the British Isles, is on similar lines. It includes also two papyri, one at the British Museum (Papyrus 121) and one in the Bodleian [MS. Gr. f. 73 (p) 3396] ; a manuscript of the Koeranides ; and the text of the Byzantine Greek manuscript on alchemy (290, ff. 186-194) preserved in the library of the Earl of Leicester at Holkham Hall. The last section is the work of Prof. Otto Lagercrantz; the main portion of Part 3 was compiled by Mrs. Singer, with the collaboration of Miss Annie Anderson and Mr. W. J. Anderson. Mrs. Singer's catalogue of the scientific manuscripts of the British Isles now includes about 40,000 items, and the present catalogue is the development of one of the sections of the general catalogue. Those who have had the privilege of using the latter—a courtesy which Mrs. Singer extends with unfailing generosity to all scholars—fully realise the tremendous assistance it will give to historical research in science, and will rejoice that this part of it is now in print.

The general impression gained from a perusal of the two parts is one of astonishment at the comprehensiveness of Berthelot and Ruelle's work. As M. Bidez says, " If the faults of Ruelle's work have become apparent, it is the result of a new scientific curiosity which he was one of the first to awaken." We cannot doubt that the publication of the present Catalogue will stimulate research into the origin of no. 2886 vol. 115]

chemistry ; it will certainly render the task of workers in this field very much easier. It is, moreover, not without interest to Hellenists themselves, for surely no student of Greece can afford to neglect this early scientific or quasi-scientific literature.

The important Holkham Hall manuscript, which, at Sir Frederick Kenyon's request, the EarLof Leicester kindly allowed to be published, was brought to light by Prof. Cumont. It has here been edited, with an introduction and critical annotations, by Prof. Lagercrantz. It is entitled " Ttji «A/re/xtas r) Si.dTa^ii Kal ■t) o-vfiftoXh Kal 1) /<o7T/3oi—alchimiae apparatio et compositiones et fimi "—and is interesting not only because of the strange substitution of aAre/u'a for aAx>//xia or dX^v/wt. (a point which Prof. Lagercrantz discusses in his preface), but also because it shows that the Byzantines had original views on alchemy and did not confine themselves to reading and interpreting the works of the ancient Greek alchemists. We hope that it may prove possible to publish a translation of this MS. into English, French, or German, and so to make it more easily accessible.

E. J. Holmyard.

Our Bookshelf.

Introduction to the Theory of Spectacles. By Prof.

Dr. Otto Henker. Translated by R. Kanthack.

Pp. viii + 336. (Jena: School of Optics; London:

J. W. Atha and Co., 1924.) 135-, 6d.

The book under notice follows the lines of Prof. Henker's courses of lectures on spectacles; the German' edition from which the present translation by Mr. Kanthack is made was first published in 1921. Commencing from elementary principles, it gives an account of modern continental practice in spectacle optics, embodying the important work (in connexion with cataract lenses, telescopic spectacles, and other special aids to vision) of the Jena school under Prof. Moritz von Rohr. This has been mainly accomplished since the year 1908. While the War with its immense number of special cases of injuries to the eye undoubtedly gave a renewed stimulus to studies of this kind, many sufferers are still (as Prof. Cheshire points out in a foreword) ignorant of the aid which science can now give them. The present book should fill a great need if it gives information of this kind.

The mathematical theory goes no further than the usual Gaussian first-order treatment, but aberrational defects and means of overcoming them are explained with the aid of diagrams. The analogy between the action of the anastigmatic spectacle lens (with its stop at the centre of rotation of the eyeball) and the single photographic landscape lens, in securing freedom from the astigmatism of oblique pencils, emphasises the fact, not yet sufficiently appreciated, that a spectacle lens must be designed with the same understanding and similarly thorough analytical and trigonometric methods as for any other optical instrument. As

February 21, 1925]

NA TURE

Gullstrand pointed out, such anastigmatism cannot be secured in high-power cataract lenses without the use of non-spherical surfaces. The design of such lenses by Prof, von Rohr and their production by Zeiss is one of the most interesting matters dealt with in the book. The importance of this work to ophthalmo-logical science cannot be too fully emphasised.

A number of terms and phrases are found which should not be adopted in Great Britain without question. There are good reasons against the term " point-focal " as applied to any lens whatever, and there is no need to replace the familiar term'' bending " (as applied to a lens) by '' co-flexure." Other examples will be found.

The number of tables and charts which the book •contains render it in fact a very useful work of reference for the ophthalmologist, though it is undoubtedly more than an "introduction to the theory of spectacles " ; its scientific importance is unquestionable.

The British Journal Photographic Almanac and Photographer's Daily Companion ; with which is incorporated " The Year Book of Photography and Amateurs' Guide " and " The Photographic Annual," 1925. Edited by George E. Brown. Sixty-fourth issue. Pp. 816. (London : H. Greenwood and Co., ■ Ltd., 1925.) Paper, 2s. net; cloth, 35. net. This almanac continues to occupy the unique position that its editor has earned for it, and to have lived down all its previous contemporaries. Its general character is too well known to need description, and is maintained in the present volume, but a few welcome changes have been introduced. The most notable of these is the replacement of the tables of chemical formulae by a series of short articles dealing with the properties of the commonest of the chemical substances used in photographic processes. These will be found of real practical utility, though they need a little revision. One might, for example, be led into error by the statement that iodine is insoluble in water or by the representation of oxalic acid as if its crystals were anhydrous. There does not seem any valid reason for calling ammonium, potassium, and sodium salts as ammonium,'' potass," and soda salts respectively, and when uniformity means simplicity and offers no disadvantages, it is always desirable. The editor as usual contributes a long article, this year on" The Plain Facts of Lenses," which is eminently practical and easily understandable even by non-technical photographers. There is also a second article by Mr. T. L. J. Bentley on how to get the best results with the very small cameras that are now in vogue. It appears that 3J in. x in. is by far the most popular size as compared with either larger or smaller sizes of spools of roll-film.

Life and Science. By Prof. David Fraser Harris. Pp. 204. (London : Andrew Melrose, Ltd., 1923.) is. 6d. net.

The author, in this little work, describes in simple terms the scientific aspect of certain vital phenomena. Written in pleasant style, it appears suitable for the layman of an inquiring turn of mind, who wishes to know something of vital mechanisms without the need of a knowledge of physiology. The work opens with a chapter on the thesis that there is nothing new under the sun, and shows how man's inventions have been

no. 2886, vol. 115]

anticipated in the mechanisms found in his own body. After a chapter on mechanisms of defence, the author describes certain tissues which are characterised by possessing a rhythmic activity, thus leading up to a discussion of sleep, which is termed " life's great rhythm " : stress is laid on the presence of fatigue products in the blood, a lessened blood supply to the brain, and a diminution in the number of sensory impressions reaching that organ. In the following chapter examples of " latent life," taken from both the vegetable and animal kingdoms, are described : in the next, the rather uncommon subject of " coloured thinking " is dealt with ; in these persons certain words or sounds are associated with certain colours, especially when a concept has to be visualised : the condition occurs in perfectly normal people and has no relation to visual hallucinations. The book closes with a plea for a greater recognition of the mutual influence of the mind and body upon each other, illustrated by the subject of faith-healing.

Sunshine and Open Air : their Influence on Health, with special reference to the Alpine Climate. By Leonard Hill. Pp. vii +132+ 8 plates. (London: E.Arnold and Co., 1924.) ioi. 6d. net. Prof. Leonard Hill has brought together in small compass a mass of valuable material bearing on the health-giving properties of sunshine and open air. He analyses the scientific facts which explain the curative effects of the Alpine climate, contrasting the composition and physiological effects of high and low atmospheres. The value of this section is enhanced by a large series of comparative observations, not only on the hours of bright sunshine in numerous stations, but also by the exact measurement of the intensity of the sunlight and that of light reflected from the sky and the ground. These measurements are made both in terms of heat and of their biological action. The chapter on the influence of moisture, mist, temperature is well worthy of careful consideration, as it offers explanations of the morbidity of the town dweller and the risks of infection run in confined sunless communities. In the chapter on the biological action of light, the author has summarised a large amount of valuable work done under his supervision in the Department of Applied Physiology in the National Institute for Medical Research. This work comprises the development of instruments for the precise measurement of actinic light both chemically and by its action on protozoa, the depth of penetration of various radiations, and their influence on the blood of animals and man. The introductory chapter gives a practical account of the writer's personal experiences of the " sun cure," and the work is illustrated by some very clear half-tone reproductions.

The Chemistry of Crop Production. By Prof. T. B. Wood. Second edition. Pp. vii+193. (London: University Tutorial Press, Ltd., 1924.) 4s. 6d. The first edition of Prof. T. B. Wood's admirable little book on the scientific principles of crop production was reviewed in Nature for March 24, 1921 (vol. 107, p. 101). We are glad to note that a second edition has been called for, and that the publishers have found it possible to reduce the price from 55. 6d. to 4s. 6d. The text is unchanged, save that the examples are now based on prices current in 1924.