animals require iron, I have seen mules licking rusty iron, just as thousands of people have seen horses licking salt," to which valuable testimony he quotes an account of quails in Florida picking at the holes in the steel rails. But to appreciate fully what a man of blood and iron we are concerned with, it is necessary to obtain some insight into his views of what his plants and animals do with these relatively enormous quantities of the metal. We read on p. 5, "iron is the means of fixing the ammonia of the air in the soil to form nitrates. In any case I am sure there is a fixed law by which the ammonia of the air is fixed in the soil to form nitrates. . . ." Then, on p. 21, "it has been proved over and over again that iron is fatal to all fungi, consequently it is unreasonable to suggest that bacteria would attack a perfectly healthy animal, and destroy the blood containing a constituent which was a poison to them." And, again, on pp. 98-99, "The distinct chemical difference between fungi and what we look upon as ordinary plants, is that the fungi contain no iron or nitrogen, while these constituents are essential to ordinary plant life. It is known that iron and nitrogen are fatal to fungi, therefore the more iron and nitrogen animal life takes up in its food the more likely it is to be immune to bacterial diseases." It might not unreasonably be expected that we had here plumbed the depths, but the following shows that there are nether regions still, for on p. 42 we have the astounding statement, "It is fully recognised that iron and nitrogen in combination with the phosphates are the means by which the plant is enabled to take up the carbon of the air, . . ." and on p. 68, "it is admitted that the proteids are fatal to pathogenic bacteria." Even these are not the only contributions of the author to the study of bacteria, for he states (p. 98) "it is recognised that all classes of bacteria can only live on foods corresponding in chemical composition to themselves," which pronouncement would appear to require some explanation in view of the previous one regarding proteids, for instance, and the following, quoted from p. 33: "it is admitted that pathogenic bacteria cannot live in the presence of proteids. What the author's idea of a proteid may be we have been unable to make out, but there is no hesitation needed in regard to some of his notions regarding immunity, of which the following is a specimen (p. 60):-" Another important factor in immunity is electricity, which is so closely connected with the chemistry of the animal that it is reasonable to think that an animal of normal chemical combination will be in a position to produce much more electricity than an animal chemically deficient." Immunity is a fascinating but a very difficult subject, but the author is not deterred by the latter in his submission to the former attribute. 66 of constituting a great chemical difference.” Indeed, we should think it would! But let us read on (p. 120), “if you have a field rich in all the essential mineral constituents, in an assimilable form, and a green crop be grown in this field and ploughed in, and then a cereal crop be grown, this cereal crop will be immune to rust, to say nothing of other parasitical diseases." Here it might be said that the author is merely claiming that high manuring renders a crop more immune, did not the context show that his ideas are by no means so simple, and if the continuation on p. 120 were overlooked, while if in another field, very deficient in these assimilable mineral constituents, a green crop was grown of a chlorotic nature and ploughed in, then the cereal crop grown would not be immune owing to the imperfect chemical functions performed by what I may call a chlorotic humus." 66 And this, after all the careful work that has been done on the cereal rusts and other parasitic diseases! On p. 131 the author declares that "parasitic fungi and bacteria can only flourish when the plant (or animal) on which they feed is deficient in chlorophyll or chlorophyll matter, or their products." ་་ An interesting specimen of the author's quality appears in the following naïve passage on p. 148:Slugs, indeed, living as they do like the fungi mainly upon decaying vegetable matter, are not unlike creeping fungi, and I believe it can be shown that they are chemically of a similar composition." Again, p. 158-"I have now pointed out that there are forms of insect life that are to all intents and purposes simply an extension of the fungi." These suggestive quotations will, we are of opinion, convince the reader that the present volume cannot be said to be of any use to a serious student of science. MINES AND MINERALS OF THE UNITED STATES. Calendar Mineral Resources of the United States. Year 1901. Pp. 973 and index. (Washington : Government Printing Office, 1902.) THIS is the eighteenth volume of the well-known series issued by the United States Geological Survey, and, like those which have gone before, it is full of valuable information concerning the mineral output not only of the country itself, but also of the world generally. The book consists of a number of articles written by various experts; thus the production of iron ore is dealt with by Mr. Birkinbine, and the American iron trade by Mr. Swank. Mr. G. F. Kunz contributes some interesting pages upon precious stones, whilst the coal trade is reviewed by Mr. E. W. Parker. The consequence is that a more useful contribution to knowledge is made by the United States Geological Survey than by the British Home Office in its annual mineral statistics. The introductory remarks written by Dr. David T. On pp. 118-119 we read, although Storer does Day tell us that the total value of the minerals prospeak of the better kinds of humus, yet it may be a duced in 1901 is reckoned at 1,086,529,521 dollars, or chlorotic humus, or it may be a humus con- about 223 millions sterling; this is more than twice taining a maximum chlorophyll, or any variation the value of the mineral output of the United Kingdom between the two, which variation would be capable | last year. It must be pointed out, however, that the American figures are swollen by taking the value of the metals and not the value of the ores, but even if the comparison with this country were made upon strictly identical lines, we should still be a long way behind. In 1901 the United States produced more coal, copper, gold, iron, lead, salt and silver than any other country in the world. The yield of coal was about one-third of the world's supply. This mineral is mined in twenty-eight different States, Pennsylvania being, of course, by far the most important. Twentyfour States are producing iron ore, Minnesota heading the list with 11 million tons of red hæmatite. Montana yields about two-fifths of the copper of the United States, the Lake Superior district about onequarter, and Arizona about one-fifth. Colorado has outstripped California, and is now the leading gold-producing State. Mr. Oliphant's chapter upon natural gas is sure to claim much attention, and is of special import for those who are interested in our new supply in Sussex. The advantages of this cheap and economical fuel are lauded to the skies by the author, who reckons that the quantity tapped and supplied in 1901 exceeded one cubic mile in volume; 21,848 miles of mains, 2 to 36 inches in diameter, are employed in distributing the gas to consumers. We learn from Mr. Struthers that the United States are the largest producers of borates in the world. Most of the borax is obtained by treating the colemanite of California. two volumes of the original work, which deal with special climatology, as it has been found "impracticable to translate them. This is greatly to be regretted, for the generalisations which constitute the science of climatology cannot be satisfactorily treated without reference to the statistical data and the means for verifying them. Moreover, a compendious review, in English, of the statistics of the various meteorological elements arranged according to geographical distribution is constantly wanted for many purposes, and either a translation of Dr. Hann's volumes, or a reproduction in an abridged form of Dr. Buchan's volume of the Challenger reports, is a necessity of which every student of meteorology must be aware. It is quite true that such a survey would be a work of reference, and would not serve as a text-book in a course of general climatology, and as that is Prof. Ward's purpose in preparing the translation, we must unfortunately wait for some other interest to prompt the translation of the two volumes of special climatology. The translator himself explains the relation of the English version to Hann's first volume : "This translation, as it stands, essentially reproduces the original. Numerous references, especially such as will be most useful to English and American students, have been added, and changes have been made in the text in order to bring the discussion down to date. A natural temptation to expand the original has been yielded to in very few cases only. Practically all of the important publications which have been issued since the completion of the second German According to Mr. Joseph Hyde Pratt, who deals with edition are referred to. Some new examples of abrasives, artificial corundum is now being employed different climatic phenomena have been added, chiefly in the manufacture of emery wheels. from the United States. It appears that Most of the examples given, bauxite is converted into corundum by means of great however, necessarily still relate to Europe, because the climatology of that continent has been studied more heat and pressure in an electrical furnace. The critically than that of any other region. A few cuts mineral monazite is far more widely distributed than have been made where the discussion concerned was imagined when its name was chosen in allusion matters of special interest to European students only." to its supposed rare occurrence; it derives its commercial value from the small percentage of thoria Among recent works, references to which have been which it contains. The quantity washed from gravels but the remarkable Russian " incorporated, Bartholomew's "Atlas" is conspicuous, and sands in North and South Carolina in 1901 published in 1900, is not, although it furnishes a large Climatological Atlas," amounted to 334 tons. number of illustrations of climatological principles. In dealing with a great work like the volume under review, it may seem ungenerous to point out a small and trifling error, but probably Mr. Birkinbine will be glad to correct the statement that ore is won 66 no true manganese " in Great Britain. The Merionethshire 1 66 ore cannot be fairly described as manganiferous iron ore when an analysis shows 25 per cent. of manganese and only 4 per cent. of iron. CLIMATOLOGY. Handbook of Climatology. Part i. General Climat- Halse, "On the Occurrence of Manganese Ore in the Cambrian Rocks of Merionethshire." (Proc. N.E. Inst. M. and M. Eng., vol. xxxvi. 1887). A distinction is drawn by Hann between climatology and meteorology, but when one deals with general climatology it is rather hard to maintain the distinction. In dealing with the analysis of climates into solar, or mathematical climate, and physical climate, with such subdivisions as mountain climate, continental and marine climates, forest climate, and such supplements as mountains as climatic barriers, geological changes of climate and periodic variations of climate, all of which are treated in the book, it is obvious that neither author nor translator would be content with the mere analysis of figures representing these different sections. The mode of classification at once suggests the causes of climate, and the investigation of such causes is practically general meteorology. It is scarcely necessary to refer to the admirable way in which Dr. Hann arranged his introductory volume to include a survey of all the general facts about climate and its local variations, and to produce a book which always surprises those who take it up by the fulness of its information and by the interest which it stimulates. There is no specific indication in the present volume as to what parts are derived from the original and what parts are due to Prof. Ward's careful editing; in any case, the result of the collaboration is a most admirable book. W. N. SHAW. OUR BOOK SHELF. Second The Steam Turbine. By Robert M. Neilson. THE history of the steam turbine previous to the reign par The chapter on the propulsion of ships by turbines is interesting. Astronomischer Jahresbericht. By Walter F. Wislicenus. Band iv. Pp. xxxii+648. (Berlin: Georg Reimer, 1903.) THIS, the fourth issue of this most valuable and useful volume, contains the references and a brief summary of contents of the astronomical literature published last year. The work is of the same high standard as in former years, and casts great credit on the labours of Herr Wislicenus and his joint compilers. This yearbook is so well known to astronomers, and has been found so valuable by them, that it is hardly necessary to dwell either on the general arrangement of the subject or on the method of treatment. The main object of the compilers was to make as perfect a record as possible of all the published papers on this subject, yet to keep the book from becoming too bulky. This they have succeeded in doing, in spite of the fact that many of the abstracts of lengthy papers are very complete. Now that the Royal Society has published the first annual issue of this branch of science (E. Astronomy) in the "International Catalogue of Scientific Literature," it seems possible that there will scarcely be room for both of these compilations, since the more perfect they become the more closely will they resemble each other. This question, however, the future will no doubt settle. There is, nevertheless, one main difference between them, in that the volume before us summarises the contents of each paper to which referlogue" is restricted to the bare references. ence is made, while that of the "International Cata W. J. S. L. It con Practical Management of Pure Yeast. By Alfred Jörgensen. Translated by R. Grey. Pp. viii+60. THIS useful little work might have received with advan(London: the Brewing Trade Review, 1903.) tage a title better descriptive of its contents. tains a condensed account of the biological methods which are employed in the author's well-known On the whole, the book is one that ought to be read laboratory in the pure culture and analysis of alcoholby students; it is practically the only book on the sub-producing yeasts. According to the preface, the leading purpose of this treatise is to enlighten the so-called ject, but we think that the author has not done so practical man in the methods of investigation employed well with his materials as he might have done. by the zymotechnologist, so that in the future the Whittaker's Electrical Engineer's Pocket Book. practical man and the technologist may work together Edited by Kenelm Edgcumbe. Pp. viii+456. with better understanding at the many important and (London: Whittaker and Co., 1903.) Price 3s. 6d. difficult problems which are encountered in the processes of the fermentation industries. No doubt the THIS little book differs in several respects from the little book is well calculated to fulfil its object if only ordinary type of pocket book; it possesses the usual the practical man will read it, and we hope it will be features a limp cover, round corners, gilt edges, and in much demand for this purpose. But whatever may a weight quite unsuited to the pocket-which serve to be the success of the book in this direction, it uncharacterise the "pocket book," but in the arrange- doubtedly deserves the careful attention of all zymoment of the matter it rather resembles a small encyclo- technologists, as it indicates the lines on which a pædia. Each branch of electrical engineering is dealt well-known investigator of great experience is workwith in a separate section or chapter, which may be ing with a view to the solution of many interesting read consecutively as if it were a brief treatise on the and complicated problems in connection with the subject. The method has much to recommend it; the organisms of fermentation. The last words on the electrical engineer who comes across some problem in biological methods of analysis and the technical ema branch with which he is not familiar can turn up ployment of pure cultures of yeast are still a very long the section dealing with that branch and read a way from being spoken, but as an advance towards summary of the whole subject; numerous references this end we cordially recommend the work to the attento recent papers will greatly help him in finding the tion of all interested in the biological aspect of the particulars which he wants. There are, of course, also fermentation industries. A. J. B. LETTERS TO THE EDITOR. The Editor does not hold himself responsible for opinions expressed by his correspondents. Neither can he undertake to return, or to correspond with the writers of, rejected manuscripts intended for this or any other part of NATURE. No notice is taken of anonymous communications.] Variation of Atmospheric Absorption. I SHOULD be pleased to know how far some observations on the change in the average absorption of the terrestrial atmosphere in this country during the last two years have been confirmed by observations elsewhere. The following table gives the mean of the best of these, made at Washington in the autumn of 1901, the spring and autumn of 1902, and in the winter, spring, and summer of 1903. Coefficients of Transmission for Zenith Sun. not give its full heating power at first, but the heating effect rises to a maximum in the course of the first few hours. If the emanation is the cause of the heat, why this slow rise? Here again the effect seems proportional to the amount of excited activity present, and not to the amount of the emanation. The connection of heating power with the emission of a rays also requires further elucidation, and the information given by the authors is not, I believe, sufficient to prove their case. It is only with great diffidence that I address these remarks to you, because Prof. Rutherford knows the whole subject at first hand, and his judgment is more likely to be correct than mine. Nevertheless, one likes to know whether others have felt the same difficulty, and whether the apparent disagreement is one of misunderstanding or has some more deep-seated ARTHUR SCHUSTER. cause. The Owens College, Manchester, November 2. Heating Effect of the Radium Emanation. THE very important and fundamental experiments described by Profs. E. Rutherford and H. T. Barnes in NATURE of October 29 will have been read with the greatest interest. Owing to the importance of the subject, I should ike to direct the authors' attention to some points in their comment and explanation which do not appear to me to be quite clear, and if I can draw from them some more detailed discussion this letter will have served its purpose. The general conclusion arrived at by the authors is that "more than two-thirds of the heating effect is not due to the radium at all, but to the radio-active emanation which it produces from itself." If I understand the description of their experiments correctly, these seem to me, however, to point to the fact that it is the "excited activity" and not the emanation that is the cause of the heating. Apparently de-emanated radium gives out an amount of heat at a rate which falls in a few hours to a minimum and then slowly recovers. Now the emanation itself begins to form again at once, so that on the authors' hypothesis the heating effect should start with a minimum and then gradually increase. The activity of the radium measured by electric methods follows the course of the heating effect, and, as Messrs. Rutherford and Soddy have explained Phil. Mag., April, not May as quoted by the authors), this is due to the fact that the de-emanated radium has still the excited activity attached to it, and this activity decays in the course of a few hours. When the excited activity is gone there is nothing but radium left, and the further changes are due to the re-formation of the emanation and its subsequent change into excited activity. During the course of the first few hours there is, therefore, very little emanation, but there is excited activity which falls to a minimum and then slowly grows again. Does not the explanation which holds for the activity also hold for the heating effect, and would it not follow that the parallelism of heating effect lies with the amount of the excited activity present, and should be assigned to it rather than to the emanation? Similarly, the emanation, according to the authors, does Radium and Plants. THE sensibility of protoplasm towards the radiations of radium is a matter of so much importance that a few preliminary experiments I have carried out on plants may be of interest. The first experiment I made in this direction was with cress seedlings. About 100 seeds were uniformly distributed over the surface of some moist sand contained in a flower saucer, and a tube containing 5 mgrs. of pure radium bromide supported at a height of 1 cm. over the centre of the sand surface. During the experiment the saucer, covered with a glass shade, was kept in the dark. It was hoped that this arrangement would show whether the radiations are harmful or not to the sensitive cells of seedlings, and at the same time indicate if they are able to act as a stimulus to evoke positive or negative curvatures. After the germination of the seeds, which took place within two days nearly simultaneously all over the sand, the growth of all the seedlings was nearly uniform. But close comparison showed that the seedlings immediately under the radium tube were to some small extent retarded in their development. The retardation was apparent in the seedlings situated within a radius of about 2 cm. from the radium bromide. Besides being smaller, these seedlings developed somewhat fewer and shorter root-hairs than those nearer the margin of the sand. In the subsequent growth the presence of the radium' evoked no curvatures in the little plants close by it, or in those more removed. Nor did it appear to exercise any noxious effects, other than the retardation just described, on the seedlings within the period of the experiment, viz. thirteen days. The plants grew up beside it and against the glass containing it, neither influenced by it nor hurt by it, so far as one could see. This experiment was repeated on two other occasions (one experiment lasting three days after germination and the other lasting four days) with the same result, viz. no curvature was evoked, but the seedlings close under the radium bromide were slightly retarded in their growth. In order to determine if motile organisms are sensitive to the radiations I enclosed the radium tube in a vessel of water containing large quantities of Volvox globator. Extraneous light was cut off from the experiment. After twenty hours many of the Volvox colonies had sunk to the bottom of the vessel, but they were evenly distributed over the bottom, and were neither aggregated under the tube nor dispersed away from it. Those that were still swimming in the water were also uniformly distributed through it, some actually in contact with the radium tube and some far away from it, but showing no sign of being attracted towards it, or of being repelled from it. It is apparent from these few experiments that the radiations emitted by radium bromide are not able to produce marked effects in a short time on these vegetable cells and tissues. Even the phosphorescent light (which is quite perceptible to the eye under suitable conditions) emitted by the radium bromide is too feeble to be effective in calling out a phototactic response. HENRY H. DIXON. Botanical Laboratory, Trinity College, Dublin. Solar and Magnetic Disturbances. was an ex on THE Kew photographic curves showed appreciable magnetic disturbances of a normal type on the evening of October 30 and early morning of October 31, but the first distinct precursor of the magnetic storm ceptionally sudden movement at about 6h. 3m. a.m. October 31, shown alike in the declination, horizontal force and vertical force curves. This movement was largest in the horizontal force, where there was a sudden increase of about 60 y (I YIX 10-5 C.G.S. unit). In the declination there was a simultaneous movement of about 7' to the west, apparently preceded by a very tiny movement to the east, lasting too short a time to be distinctly shown. The first large movements commenced about 6.45 a.m., when there was a movement of the declination needle to the west through about 34', and a diminution of 240 y in the horizontal force. The storm was most violent between 10 a.m. and 7 p.m. on October 31, but there was a large amount of disturbance until 3 or 4 a.m. on November 1. The traces from the Kew magnetographs-declination, horizontal force and vertical force alike-went off the sheet repeatedly, so that the full extent of the disturbance cannot be derived from them. A declination magnetograph, however, of lesser sensitiveness recorded apparently the complete movement, and showed a range of about 2° 12'. Between 1 and 7 p.m. there were at least twenty to and fro oscillations of the declination needle-each occurring in but a few minutes of time-the amplitude of which exceeded 20'. In addition to these there was a very large number of smaller oscillations. At times these followed one another so rapidly that they can hardly be seen apart on the photographic sheet. In the horizontal force there were also very numerous oscillations. The general tendency from 7 a.m. to 10.30 a.m. was towards a reduction of the force. From 10.30 a.m. to I p.m. the oscillations were about a value not far from the normal. At about 1 p.m. there commenced a rapid rise, which in twenty minutes amounted to about 690 y, the curve going off the sheet. During the next two and a half hours the trace was often off the sheet. Between 3.50 and 5.10 p.m. the trace crossed the sheet from edge to edge, representing a change of about 750 y, or somewhat more than one twenty-fifth of the value of the whole horizontal force. The vertical force disturbance was small at first, and did not become really large until nearly noon on October 31. there were numerous large oscillations, the curve going off the sheet repeatedly on one side. At about 1.40 p.m. there was an oscillation where, in the course of five or six minutes, there was a decrease and increase of more than 350 y. The trace remained off the sheet from about 3.30 to 5 p.m. Between 5.10 and 5.50 p.m. the force diminished about 450 Y. From noon to 7 p.m. The storm is much the most notable recorded at Kew National Physical Laboratory, Richmond, Surrey, IN connection with the magnetic storm of Saturday last, October 31, it may be of interest to record that observations made between 10 and 11 a.m. on that day by Prof. Callendar and myself showed a violent distortion and reversal of the C line of hydrogen in the neighbourhood of the great sunspot group, which was then a little past the central meridian. A notable feature was the apparent detachment of a portion of the dark C line, the separated part presenting the appearance of a cloudy patch, displaced towards the violet by about three tenth-metres. The observations were unfortunately interrupted by clouds. A reversal of the C line over the same spot had been observed on the two preceding days, but though on these occasions the bright line was more brilliant than on October 31. there was much less distortion of the dark line. tific worker and as an administrator, and who was one Dear Mr. Omond, Edinburgh, Dr. Shaw's address to the subsection of astronomy and meteorology of the British Association in September last, by its appearance in NATURE of September 17 has quickly and effectively reached the whole scientific world, and it is misleading in important directions, quite unintentionally, I believe. The absence of all reference to the meteorological work done by Buchan, Stevenson, Aitken, Buchanan, Murray, yourself and others will probably receive an interpretation which I hope is erroneous, for I cannot think that Dr. Shaw would designedly belittle the valuable work these men have done, which is recognised as being of a high character all over the world. But it seems to me more remarkable that Dr. Shaw should have made no special reference to the work of the Ben Nevis Observatories. In that work a very great, costly and laborious effort has been made to advance meteorology and to add to knowledge, and this has been done mainly through private enterprise, under the guidance of the foremost scientific men of our time, including Kelvin, Tait, Buchan, Murray, Copeland, Aitken, Buchanan, Stevenson, and many others. The discussion of the outcome of this great experiment in connection with the physics of the atmosphere has only recently begun. It cannot be quickly finished, much time by many experts must be given to it, and it cannot fail to cost a large amount of money. My special object in writing to you is to suggest that, as honorary secretary of the Ben Nevis directors, you should in some way supply what I regard as an incompleteness in Dr. Shaw's address by briefly stating how the work of the Ben Nevis Observatories now stands, and what prospects there are of its yielding further important additions to knowledge. Very faithfully yours, ARTHUR MITCHELL. In accordance with Sir Arthur's suggestion I beg to make the following statement explanatory of the present position of the Ben Nevis Observatories, and to note briefly the work carried on at and in connection with these observatories. When the observatory on Ben Nevis was opened twenty years ago very little was known about the condition of the atmosphere above a few hundred feet height over the British Islands. The first object aimed at was to determine the meteorological constants for that position, and the relations of the air there to that at sea-level in the neighbourhood. This latter part of the work has only been adequately carried out since the establishment of the Fort William Observatory in 1890. The observations down to the end of 1892 have been published in two volumes of the Transactions of the Royal Society of Edinburgh (Nos. 34 and 42). The first of these was printed at the expense of the Royal Society of Edinburgh, and the second at the joint cost of the Royal Societies of London and Edinburgh. Another volume is in the press, and will be issued shortly. The constants referred to are:-(1) The average value at each hour of the day for each month of the year of barometric pressure, temperature of the air, humidity, rainfall, direction and force of wind, amount of cloud and sunshine on Ben Nevis. (2) The relation of each of these to the corresponding sea-level values at Fort William. Immediately arising from these average values is the question of the changes induced on them, especially on the second series, by different conditions of weather-that is, the determination of the vertical gradients of pressure, temperature, &c., under varying atmospheric conditions. This discussion has been partly carried out, and the more important results arrived at are summarised in papers appended to the two volumes of observations. One of the most interesting practical aspects of the Ben Nevis records is their application to the reduction of barometric readings to sea-level, a subject which is at present engaging great attention in this country, in the United |