(3) In the editor's preface to Dent's Scientific nitrogen, the proteins, and the colloid substances. I Primers, in which the one under review is included, is from this fourth German edition that the French ! we are told that the great advances in knowledge the fact that a French version is now published may translation which is before us was prepared, and during the last thirty years necessitate a re-statement be taken as in itself a tolerably satisfactory indica of the theories of the different sciences. tion, not only that Ladenburg's book has established itself as a work of permanent value in the estimation of chemists irrespective of nationality, but also that r is free from national bias, such as is frequently me with in historical works. The translation bears every evidence of having had much careful attention bestowed upon it, and it gives a faithful representation of the original. The book is produced in a creditable style typographically. This may be true of chemistry if it were a question of publishing a new treatise or even a students' textbook; but when we consider that this miniature volume of a hundred pages is intended for a student possessing no previous acquaintance with the subject and without the leisure to study it systematically, we cannot be surprised that the advances in knowledge are not very apparent. We might even go further and state that, except for a passing reference to radium and the noble gases, and the use of the words "stereochemistry" and polypeptides," the book might just as well have appeared thirty years ago. With the very limited space at his disposal, Prof. Tilden has made good use of his materials, and has compressed into a small compass a very readable and suggestive account of the elementary facts and theories of chemistry. J. B. C. OUR BOOK SHELF. (1) Biologisches Praktikum für höhere Schulen. Er (1) THIS is an attempt to compress into seventy-one octavo pages a practical introduction to the study c the comparative anatomy of plants and animals, together with a certain amount of experimental physiology. There are seventy-five text-figures and nine plates. A considerable number of types, ranging from: Histoire du Développement de la_Chimie depuis bacteria to mammals, are dealt with in a very scrapp Lavoisier jusqu'a nos Jours. By Prof. A. LadenA large proper. and superficial manner in the text. burg. Traduit sur la 4 édition allemande. By tion of the illustrations are borrowed from the works Prof. A. Corvisy. Pp. v+388. (Paris: A. Hermann of well-known authors. They are well reproduced, but et Fils, 1909.) Price 15 francs. the text and explanations of the figures are very inFORTY years ago, the first German edition of Laden- adequate. A plate containing figures of the skeletons of a frog, a dog, and part of the skeleton of a bird burg's "Lectures on the History of the Development (apparently there was no room for the skull, which of Chemistry during the past 100 Years" was pub-is omitted), without a single bone labelled, is not lished. This was a relatively small book of 320 likely to be of very much service even to the most pages, which presented, in the course of fourteen elementary scholar. Doubtless, however, there are lectures, a carefully drawn and evenly balanced sketch of the progress of chemistry subsequent to the time people who are gratified by observing a resemblanc between an actual specimen and a book illustration. of Lavoisier. At the date of its publication it was and they may even think that they have learnt someunique in dealing, in a logical and consistent manner, thing by comparing the two. It is only fair to the with the progress of the atomic theory in its applica- author to mention that the book is intended to be tion both to inorganic and to organic chemistry, and used in conjunction with the instruction of a teacher. in serving at least as an introduction to the particularly who, no doubt, would be able to supply many of the difficult and complicated period in the history of organic deficiencies. chemistry which began in the 'thirties and extended to the late 'fifties or early 'sixties of last century. It was not until about four years later that this period was dealt with, a good deal more elaborately, by Kopp in his "Development of Chemistry in Recent Times" (1873). A specially valuable feature of Ladenburg's lectures was the abundance of references to the literature, which tended to encourage the reader to extend his knowledge of particular branches of the subject by consulting the original papers of the various authors. A second German edition was called for in 1887, when the original book was revised, and was extended by the addition of a fifteenth lecture. In 1900 an English version of Ladenburg's "History" was published, which was translated from the second German edition, but included various corrections and minor additions by the author, and also a sixteenth lecture, specially written for this translation. A revised English edition appeared in 1905. The third German edition (1902) was merely a reprint of the second edition with the sixteenth lecture added to it, but in 1907 a thoroughly revised and very considerably enlarged German edition appeared, which extended to more than 400 pages, and contained seventeen lectures, the subject-matter being brought up to date as fully as possible, and including accounts of the progress of discovery in connection with such recent subjects of extended investigation as radium, asymmetric (2) This little book is addressed to school teachers and students of nature, and is intended to serve as a guide to a large number of simple experiments in animal and vegetable biology. It is very suggestive, but the style is rather too much that of a cookery book, and the work suffers greatly from over-condensation. A good practical course on general physiology, in itsel a very desirable thing, might be founded upon it by an experienced and well-read teacher of biology, but it would take a very long time to carry out all the experiments in a satisfactory manner. Pp. Inborn Errors of Metabolism. The Croonian Lectures DR. GARROD delivered before the Royal College o JULY 22, 1909] NATURE shape of even a condensed account of the matters specially selected by Dr. Garrod, and so one need only mention that the anomalies treated at length are albinism, cystmaria, alkaptonuria, and pentosuria. It must not be supposed that the examination of Practical Testing of Gas and Gas-meters. By C. H. THIS is a laboriously complete compilation of the A By E. G. THIS book, written by an ardent disciple of the late LETTERS TO THE EDITOR. expressed by his correspondents. Neither can he undertake Lord Rayleigh showed that, on the hypothesis of the μ k=32m3 (μ - 1)2 64 the refractive index, and N the number of molecules per He showed, further, that the same holds, where k is the coefficient of extinction of energy, cubic centimetre. Optics if the particles locally affect the inductive capacity of the equation may be deduced from the electromagnetic theory medium. In the forthcoming new edition of my it will be proved that the equation is independent of theory, provided u is nearly equal to unity; the limit of its phase at the origin of the scattered light the square of applicability is only reached when there is a retardation of which is appreciable, and it can be shown that this is actually the case except within the region of anomalous dispersion. The range of the formula may be further increased if (2-1) is written for (μ-1)2. For N I have used Rutherford and Geiger's value index of air, k may be calculated. If h is the height of 2-72 X 10', and with the known value of the refractive the homogeneous atmosphere above the point of observation, e-kh is the fraction of light which would reach the observer if no light were lost in any other way than by molecular scattering. In the following table the transAbbot's observed figures. The first column gives the wavemitted light calculated in this manner is compared with length, the second column contains the observed values of the transmitted energy for Washington, taking all observations into account, while the third column gives the number calculated from the observations on February The last 15, 1907, when the air was exceptionally clear. The calculated values are entered into the fourth column. three columns give the corresponding numbers for Mount Wilson. The selected clear day in this case was October II, 1906. ... 0 72 Washington Mount Wilson Wave- Observed Observed mean clear day mean 4× 10-5 5 0'55 Calcu Observed Observed Calcu clear day la'ed 076 0.76 0.87 0.85 0.89 89 O'94 0.89 O'92 0'95 o'96 0.96 O'94 0.97 0.98 0.84 0.87 0.84 0'90 ... 0.87 O'94 ... 0'98 0.96 O'99 o'90... 096 ... o'99 ... O'97 The close agreement between the two last columns shows that on a clear day on Mount Wilson atmospheric absorption is practically accounted for by molecular scattering. There is a slight indication of selective absorption in an additional the red, but otherwise the columns are in complete agreement. On the average day there seems It is remarkable that, absorption of about 2 per cent. even at Washington, the calculated absorption for blue at the sea-level the greater part a clear day is due to scattering light should so nearly agree with the calculated value; The large diminution in the this means that even intensity of blue light at Washington on the average day seems to indicate that there is a substantial amount of scattering by small solid or liquid particles. The figures for Mount Wilson give us confidence in the trustworthiness of Mr. Abbot's determination of the solar constant, because it is clear that the total effect of the atmosphere can be eliminated with greater certainty if it is mainly due to the permanent constituents of the atmosphere, and not to matter which is variable in amount. As the top of Mount Wilson is less than 1800 metres above sea-level, we may conclude that at high elevation the blue colour of the sky is completely accounted for by molecular scattering. That the scattering sets a limit to the transparency of gases must be kept in mind in discussing problems of solar and stellar physics. We may feel confident, for example, that what is called the reversing layer can only have a small thickness, for otherwise we should not be able to observe so far into the ultra-violet as we do. 66 an The scattering may profoundly modify the character of the spectrum, as I have explained in a paper on Radia tion through a Foggy Atmosphere" (Astrophysical Journal, vol. xxi., p. 1), in which it is shown how increased thickness, without change of temperature, may convert absorption line into a bright line. It seems to me probable that the bright and dark flocculi shown in spectroheliograph pictures may find their explanation chiefly in variation of thickness in the absorbing layer, the bright patches being due to increased thickness. The transparency of interstellar space has recently received a much needed critical discussion at the hands of astronomers, and Prof. Turner has applied the law of scattering to explain certain discrepancies between visual and photographic magnitudes. The value he gives for the opacity allows us to calculate the average density of the matter which is diffused through space on the supposition that it is gaseous. If the value of (μ-1)/D (where is the refractive index and D the density) be taken to be approximately equal to that of air, I find that the number of molecules per cubic centimetre in space would have to be of the order of a million, and the mean free path of the order of 3000 kilometres. Although not directly connected with the subject which forms the main part of this communication, I would like to point out that the same analysis which gives the coefficient of extinction in terms of the retardation of phase at the source of the scattering also gives a resultant force acting on the molecule in the direction in which the light is passing. When summed up for all the molecules this force is found to be identical with what is generally called the " pressure of light," for if E represents the energy density, the force acting per unit volume on the scattering molecules is found to be kE, where k is the coefficient of extinction. There is a widespread impression that light pressure only acts on particles the linear dimensions of which include several wave-lengths of light, but this is not correct. The determining factor is the extinction of light, whether by scattering or by absorption, as indeed appears if we take the view adopted in Prof. Poynting's work on the subject that a propagation of momentum accompanies the transmission of light. The momentum is destroyed equally whether the molecules act as scattering or as absorbing centres. The extinction by scattering near the surface of stellar bodies does not, however, appear to be sufficient to cause any measurable effects comparable with their gravitation. ARTHUR SCHUSTER. The Fixation of Nitrogen by Soil Bacteria. MAY I be allowed through the columns of NATURE to ask Prof. W. B. Bottomley a few questions with regard to his paper on Some Effects of Nitrogen-fixing Bacteria on the Growth of Non-leguminous Plants" (Proc. Roy. Soc., B, lxxxi., 1909, 287), abstracted in NATURE of May 13 (vol. 1xxx., p. 327), as I had not the opportunity of being present when the paper was read? Prof. Bottomley bases his conclusions on experiments to show that Pseudomonas, the bacterium associated with the legumineus plants, will fix mere nitrogen in an artificial These differences would almost seem to be within the range of experimental error, but in any case, does not the demonstration require a further statement of how much nitrogen Azotobacter alone would fix? Other observers are accustomed to get fixations by Azotobacter alone of from 5 to 20 mgm. of nitrogen per 100 c.c. of such a culture solution, the maximum being about 10 mgm. of nitrogen fixed per gram of mannite. The only conclusion that could be drawn from Prof. Bottomley's figures would be that Pseudomonas injuriously affects the power of Azotobacter to fix nitrogen, supposing that a reasonably active culture of the latter had been used. Turning to the field experiments, in which Prof. Bottomley claims to get an increase of crop by adding cultures of Pseudomonas and Azotobacter to soil which presumably already contains both organisms, data for estimating the probable experimental error are again lacking. From the Rothamsted experiments, where we may assume the conditions are more than usually favourable to exactitude, the mean error of a pair of similarly treated plots in a single year is about 10 per cent., which would more than cover the differences observed by Prof. Bottomley's experiment with oats. In another experiment with barley, Prof. Bottomley obtained a higher percentage of nitrogen in the corn from the treated strip than in the corn from the rest of the field, 1.76 against 155 per cent. (I presume that "milligrammes of nitrogen per cent." is a clerical error). In view of the comparatively small changes in the composition of the grain of a cereal which are usually effected by large variations in the supply of nutrient, I should like to know from Prof. Bottomley if duplicate samples were taken from different parts of the untreated section of the field, and what range of variation they showed in their nitrogen content. Coming to the next experiment, it is difficult to judge how far a bulbous plant like Galtonia candicans is suitable for experiments on nutrition, but it is rather necessary to know what relation the weight of the bulbs planted bore to those harvested. Prof. Bottomley only says that 250 bulbs of equal size" Can were planted in each bed. he let us have the weights in each case? Moreover, he tells us that the treated bed was twice watered with the culture solution, the control bed being given pure water at the same time; was the same amount of water given to each, and how much of the culture solution was applied for it contained monopotassium phosphate, sodium chloride, &c., which may well have been a considerable factor in any beneficial effect experienced? Prof. Bottomley will perhaps forgive me if these questions may seem somewhat critical of his conclusions, but any communication appearing in the Proceedings of the Royal Society must be taken into account, and one therefore wishes to have the data necessary for determining the weight to be attached to the results. A. D. HALL. The Rothamsted Experimental Station, July 12, 1909. Occasional Unexplained Ringing of House-bells. AN observation sent me by Mr. Alexander Sinclair, of Swansea, to the effect that during a thunderstorm drops of water leaking through the ceiling "assumed a pear shape and jumped 9 inches almost horizontally to the curtain rings above the window,' suggests that house-bells of the ordinary non-electric type may occasionally be rung by this means. I picture the process as follows:-The bell wires collect atmospheric electricity, by induction or otherwise, which the walls are insufficiently conducting to carry off freely; consequently the bells get charged, are attracted to a neighbouring wall or pipe, and released suddenly by a spark. This little lateral jerk rings the bell. I put the simple suggestion on record because I sometimes hear of an inclination to attribute the phenomenon to less familiar causes. OLIVER LODGE. JULY 22, 1909] Musical Sands. NATURE In an interesting letter Mr. Carus-Wilson gives us the results (NATURE, July 15) of further observations made by him on a phenomenon on which he has written from time to time. I believe I have suggested to him in years gone by-if not, perhaps you will allow me to suggest now-the possibility of the musical ring of certain sands in motion being due to their consisting largely of grains of hyaline quartz. That fact, if ascertained, would account for the ring of the grains in motion, while the smoothness of their glassy surfaces would facilitate their motion, and increase the force of their mutual impact, tending to raise I have never had an the pitch of the note produced. opportunity myself of making a microscopic examination assortof such sands, but I venture to commend such an examination to Mr. Carus-Wilson's consideration. The ment of the sands by the wind into possibly more rounded A. IRVING. and more angular grains may also throw some light upon the matter. Bishop's Stortford, July 19. Wych Elm Seedlings. THE prolific flowering of the Wych elm, Ulmus montana, this year must have been followed by the formation of unusual numbers of fertile seeds. At present the ground beneath these elms in my garden is covered with hundreds of their seedlings, many of which have already developed a second pair of serrated leaves. The elms themselves seem to have suffered from the strain of producing so large a crop of fruits, for their leaves, though now of the usual size, were very late in appearing, and are sparsely distributed on the branches. ROSAMOND F. SHOVE. 26 Blessington Road, Lee, Kent, July 13. when a chick was POPULAR NATURAL HISTORY. a handy and R. LEA'S " Romance of Bird-life, MR. fully illustrated volume published at a marvellously low price, covers the whole life-history of the bird, from the egg upwards, the twenty-one chapters containing a summary of the observations of a great many writers on ornithology arranged in a masterly One of the concluding and most attractive form. chapters deals with the birds of the past and vanishing species, and is illustrated with a reproduction of a curious old wood-cut published in 1601, representing early voyagers knocking down dodos and other birds with sticks on the island of Mauritius. In that upon "Wisdom and Folly " we have anecdotes bearing on the intellectual capacity of birds. There are many instructive passages in the book, which is quite a mine of information. It is stated that in more than cheeping one instance, if while still in the shell the mother uttered a note of warning, the cheeping stopped instantly; and it is that the simple pointed out that this teaches us language of call-notes is instinctive, for the chick cannot possibly have learnt their meaning by experience. Nestlings the food of which is placed in their mouths by their parents cannot be taught to pick it up from the ground like chicks until they are much older. Young moorhens, however, which are fed from their mother's beak at first, will peck upwards at anything that is offered to them, but not downwards. So far as the author is aware the frigate bird is the only species which ever carries on fishing in mid-air, waiting until the flying-fish are startled from the sea by some large fish which preys on them below the surBeing an Account of the Education, 1 "The Romance of Bird Life." Courtship, Sport and Play, Journeys, Fishing, Fighting, Piracy, Domestic Pp. 376; illustrated. and Social Habits, Instinct, Strange Friendships and other interesting By John Lea. Aspects of the Life of Birds." (London: Seeley and Co., Ltd., 1009.) Price 55. face; other fishing birds follow them into the water. 99 66 Almost anyone seems to feel capable nowadays of writing a book on British birds, and, in good truth, there is material enough to compile from. Time was when to write an account of British birds was an undertaking attempted by few, and those only who had made the subject their main study for many years, and were on all hands accounted authorities. Now almost anyone does it, and there is a perfect stream of books on this subject. They come out so frequently that, although the title has been turned and twisted in a great variety of ways, it has even been found impossible to discover fresh and original names to distinguish them by. Most of them put forward some special claim upon the public. Many of them purport to cater for the ignorant and the beginner; one, indeed, made a point of picking brains without Here is one "with a new method acknowledgment. This book has been written with of identification." the exclusively practical object of enabling persons unBy the grouping of acquainted with British birds to identify them by their most obvious characteristics. Ruddy-breasted Birds," "Black-and-White Birds, birds, as here carried out, under such headings as "Trunk-climbing Birds," it is claimed that the birds are presented to the beginner as he himself sees them. Where necessary, notes are appended to the descriptions indicating those birds with which the one described is most likely to be confounded, and the chief characteristics by which it is to be distinguished from them. Before proceeding to observe birds, however, the user of this book need do no more than read through the list of group-headings. The book is, in fact, another attempt at a royal road to a knowledge of our birds. The idea has been tried over and over again in some shape or form, both here and in America, but we do not think it will ever be successful. In the present case the difficulties of grouping begin to be apparent very shortly. a group heading will convey nothing to the beginner without good pictures. In the end the author is left with three birds, the jay, the goldfinch, and the white first are so conspicuous that perhaps they do not want wagtail, which do not fall into any groups. The two grouping; but, really, after some of the grouping, those which are "brown above and white below," it e.g. putting the hedge sparrow and some others among seems rather like straining at a gnat not to have dropped the third in among the black-and-white birds. We are glad to read that there are a few breeding pairs of kites in the Midlands of England, and hope "Skuas as 1 "British Birds and their Eggs, with a New Method of Identification." By J. Maclair Boraston. Pp. x+301; 136 coloured illustrations. (London and Edinburgh: W. and R. Chambers, 1909.) Price 65. net. would be hard to find. Young, egg collectors are also provided with a simple guide to identify their finds. A part of a larger work, "The Young People's Nature-study Book," it is in the form of a pocket-book, with blank leaves at the end for making notes on the spot. The system of this key is as follows. The nests are grouped under the headings according to their locality and position. Turning to the particular section to which a nest belongs we find additional characteristics of the nests and eggs described, which it is hoped should lead by process of elimination to a correct result. The eggs igured on the four coloured plates are those most generally confused. They can hardly be expected to be very good, but will be useful. The introductory remarks are instructive, and there are some photogophs of nests, There is a casufed list of the birds | value, this has been done so inadequately that it m ***ated in the Werk, and an work, so that every as well have been omitted altogether. There are suce bata'ya given to those who try to learn birds' nathes birds, the Lapland bunting and shore lark, for instate in Bus of Dinstrations of the eggs of all British- I the status of which on the British Est has entire breeding birds appear in the sixteen piatra devoted to altered since Johns wrote; yet the articles on thes that part of the ajest, Some of the plates of birds species are left just as he wrote them. The editor be But in the great majority of cases also brought the scientific arrangement of the speces the thresstong at process has probably played sad tricks up to date. If this was to be done, more care show with the colours, and some of the pictures are mis-, have been taken, when the order and sequence of the kading Others make the bird-lover shudder; for species was altered, to avoid absurdities conseque horrible and appalling, crudeness of colour their equal upon careless revision of the articles. As it is, we are told that the black tern is scarcely less aquatic than the whimbrel; that the name laughing gull is often giver to the common gull; that the snow-bunting does no confine itself so closely to the Arctic regions as our homely reed-bunting, and various other absurditie all of which are due to the fact that the use of the expression "the preceding species" has not been revised. Harmless as are these misstatements to the seasoned ornithologist, they might easily confuse the beginner. A large number of species included in the older editions of Johns's work have been omitted from. this edition, presumably because of their rarity. But this weeding out, if done at all, should have been done consistently, and on some definite plan. Here we find that while the whole of the rarer herons, including the little bittern (which is believed to have bred with us, have been left out, the black stork, a very rare casual visitor, has been retained. The spotted eagle, whica has only occurred on a very few occasions, is included, while the blue-throated warbler, an annual visitor, sometimes in some numbers, has been cut out. Then why include the little crake and not Baillon's crake? Why the Pomatorhine skua and not Buffon's skua? The black-necked grebe (which has bred in this country) is not included in the text, though it is figured. But it is needless to go further through the list, except to say that one very rare bird, the lesser grey shrike, has been inserted. The statement that the green sandpiper breeds probably in wild parts of Surrey, Sussex, and Hampshire has been added to Johns's account of this bird because "the Son of the Marshes considers that it does so." More definite information would have been very desirable. There is a glossary of provincial names and of technical terms, and an index. The old (and often unsurpassed) wood-cuts with which we have been so long familiar no longer appear, and we cannot but regret them. Instead we have sixtyfour original coloured plates, comprising 256 figures. Many of these are absolutely charming and excellent portraits of birds, and altogether they are by far the best coloured pictures of our birds we have seen in a book published at anything like so low a price as this. The colour reproduction has been much more successful than usual, for which the artist may well be pleased and the publishers congratulated. Mr. Vos has issued the second and third parts of a description (illustrated) of the rambles of two friends in search of birds' nests near London, comprising the results of two seisons. They seem to have been exceptionally fortunate in finding many interesting birds and nests, and some which would not have been expected. For instance, a snipe's nest almost within earshot of Bow Bells seems wonderful. But even more so in some respects, perhaps, is "a little colony of three pairs" of carrion crows on a small island; for in our experience, even where crows are common, it is most unusual for these unsociable birds to nest in close proximity to one another. The situation of one nest, In the top of an elder-tree, about twenty-five feet from the ground, seems unusual in a country where big trees are to be found, and the egg described as about an inch long was very small, an average crow's egg measuring an inch and three-quarters. The third part concludes with a grouping of the birds mentioned to aid in their recognition; a description with figures of the eggs; a synopsis, an alphabetical index of some of the birds mentioned, and a general index. A number of nests have been nicely photographed for the book, but the photographs of stuffed birds are open to criticism, as is usual. Some of our best and really competent ornithologists have from time to time considered the possibility or advisability of editing Johns's classic, but they have feared to tread. With regard to the present edition we can only regret that a good old book has been spoilt to some extent. Fortunately, not much has been done to it, for although the editor claims to have rectified statements as to the local distribution of Various species which, with the progress of time and local changes, no longer apply, and to have added facts here and there which he considered of some For The Young Poude Windx nest Chet A Simple Guide to Identify the Nexts of Ciumson Respic Rinde' Byte Rey S, N. Sedgwick. Pp. or davicon Nobert Civy. Peix, het: "Rods And Pen Nests and Fax bound sa and near Great Towns" Be Third series, pp. xii - 40 RCA Rady in Pen Nagsex By the late Rev. C A Johns | སྙད་ ། Ulestrated with na coloured The account of the principles and measures which Baron von Berlepsch advocates for the exercise of a rational protection of birds as carried out at Seebach will be read with interest and profit by the many people who like to feed the birds in winter and get them to breed in boxes. The main features of the protection here treated of are the provision of shelter woods and plantations, pruning bushes and trees in such a way as to provide nesting situations, winter feeding, and making up for the loss of natural nestingplaces of the breeders in holes consequent upon the removal of old and decayed trees. With planting for birds we are not so much concerned in England as 1 "How to Attract and Protect Wild Fr" By Martin Hiesemann, translated by Emma S. B„heim, with an introduction by Her Grace the De bess of Bedford Pp in; i ustrated. (London: Witherby and Co., Price is Si net |