THE GEOMETRY OF FORCES. Geometrie der Kräfte. By H. E. Timerding. Pp. xii+381. (Leipzig: B. G. Teubner, 1908.) Price 16 marks.

IN

N this admirable volume Prof. Timerding gives a systematic and original treatment of the geometry of forces and force-systems in which for the first time, so far as we are aware, an adequate knowledge of modern geometrical research has been utilised in a text-book of mechanics.

Ever since the great work of Plücker, that large and most attractive department of mathematics known as the geometry of the linear complex has been found to be intimately connected with the geometry of forces. It is sufficient to recall the fact that whenever six forces applied to a free body are in equilibrium, the forces must lie respectively on six rays of a linear complex. In chapters viii. and ix. of Timerding's book now before us we have an admirable treatment of the application of the theory of the linear complex to the theory of systems of forces. The many interesting matters set forth in these pages show how greatly the advancement both of the geometrical theory and the dynamical theory is promoted by their association.

The statical and dynamical significance of the linear complex is closely connected with the fact that each ray of the complex is reciprocal to that screw of which the axis is the axis of the complex, while the pitch of the screw is the parameter of the complex. Many of the geometrical properties of the complex follow directly from this general principle. For example, on p. 107 it is shown that four linear complexes have two real or imaginary rays in common. This is an immediate consequence of the fact that one cylindroid can always be found of which every screw is reciprocal to any four given screws. As there are two screws of zero pitch on the cylindroid, these lines are, of course, the two common rays of the four linear complexes defined as being reciprocal to each of the given screws. We congratulate Prof. Timerding on his recognition of the proper place for the linear complex in the forefront of a text-book on the geometry of forces.

The theory of screws has received in this volume a treatment even more ample than that which it has already received in the works of Fiedler, Schell, Budde, Minchin, and more recently in the "Encyclopädie der mathematischen Wissenschaften." The excellent

work of Harry Gravelius, "Theoretische Mechanik Starrer Systeme," contains a complete account of the theory of screws up to the date of its publication in 1889. Much of the work done on the subject in the succeeding decade has been available for the "Geometrie der Kräfte." It may, however, be remarked that certain developments of the theory which have appeared since 1900 have not been included in Prof. Timerding's volume. The theory of screw-chains, by which the theory of screws has been extended to any material system, is also not discussed. A suggestive reason for this omission is given in the preface (p. vii), where Prof. Timerding says that, in his opinion, the theory of screw-chains would require a new and voluminous treatment of the whole of mechanics in which the rigid body would appear as the first element.

Observing that the laws for the composition c twists and wrenches are identical, the author, as others have done, uses the word dyname to signi either a twist or a wrench. For a large part of the subject the use of the abstraction signified by the word dyname is very convenient, and considerate use has been made of the important labours of Study on the geometrical theory of dynames.

In an interesting chapter on "Die Reyeschea Strahlencomplexe" the author brings into its de prominence the fundamental importance of th "Geometrie der Lage" in kinematics. This chapte contains many admirable theorems, and we could onl wish that such instructive and beautiful ideas as ar here set forth were more generally introduced in the teaching of mechanics. Due acknowledgments made throughout the work of the important contrib tions to the geometrical theory of forces by the la Prof. Charles J. Joly.

The chapter on the cylindroid may be specially cormended, and prominence is given to the theorem the the projections of any point on the generators of a cylindroid lie on an ellipse. We may, however, noe that the proof here set forth is not that by which th theorem was discovered, as shown in the origina volume on the theory of screws published in 1876.

A sufficient account is given of the various systems of screw coordinates, and, following the analogy the resolution of forces, Prof. Timerding uses notation which divides the coordinates of a screw in: two groups of three each. It is, however, often cc-. venient to use the six symmetrical coordinates of screw referred to six co-reciprocal screws.

We are glad, indeed, to commend this most exce lent work to the attention of teachers and students of theoretical dynamics. We are sure that if the book were translated into English it would form a ver valuable supplement to the existing English books. It would give the student an adequate idea of the extent to which modern geometrical theory and th theory of forces act and react on each other to the vas benefit of both. ROBERT S. BALL.

THE DISTRIBUTION OF GOLD ORES. Gold: Its Geological Occurrence and Geographica Distribution. Maclaren. By J. Malcolm P xxiii+687. (London: The Mining Journal, 1908. Price 25s. net.

DR.

one

R. MACLAREN begins his preface with the remark that "the writer who would add

more treatise to the literature of the

study of ore-deposits must needs show justifcation." Any apology for the publication of his useful book is, however, quite unnecessary, for the increase by four times of the gold yield of the work during twenty years has been attended by a voluminous and scattered literature. Students of mining geology will be grateful to any author who undertakes the great labour of compiling a summary of recen work on gold and its distribution.

The longest and most valuable section of Dr. Maclaren's book is occupied by an account of the geologica

structure and mining history of all the chief goldfields of the world. This part of the work occupies 544 pages. The goldfields are classified by continents. Those of Europe are described first, and in proportion to their economic importance receive longer notice than those of Australia and South Africa. The longest section is that on the goldfields of North America. Each field is noticed separately; the descriptions are necessarily short, but they are concise, and are accompanied by useful reference to recent literature. The minor fields are described at relatively greater length than the others; and thus Kalgurli, with its "Golden Nile," is dismissed in four pages, including a full-page map and another figure. This distribution of space is, however, probably the most useful, as the less-known fields are often very instructive and their literature is less accessible. The author has travelled extensively, and his accounts of many fields have the advantage of personal knowledge and original information. The descriptions of the fields are therefore inevitably of : unequal merit.

Among the most interesting sections are those on the mines of New Zealand-though as a New › Zealander, it is strange that the author places Reefton in Westland, and spells the name of the founder of the New Zealand school of mining geologists Uhlrich-of Queensland (the author was once on the staff of its Geological Survey), and of Mysore. The historical introduction to the Mysore gold mines is of especial interest, and the author rejects the view that the ancient mines there can have been those from which Solomon and the Phoenicians obtained their supplies of gold. Dr. Maclaren remarks that India was then a civilised State, which needed more gold than it produced; and the Israelites could only have obtained gold there by barter, for which they had nothing to offer. This conclusion, therefore, strengthens the view that the Ophir of the Phoenicians must be in southern Africa, and that the gold probably came from the prehistoric mines of Rhodesia.

Dr. Maclaren's account of the separate goldfields is preceded by an introduction on the chemical and physical properties of gold, on natural and artificial I compounds of gold, and on the theories of the formation of gold ores. The speculative section of this introduction is remarkable for the author's advocacy of somewhat extreme positions. Thus he denies the origin of any important ore deposits by other agencies than meteoric waters. He admits that there may be some magmatic water; but even when he allows that the gold is due to magmatic emanations, he holds that the water in which it is dissolved comes from a superficial source. He also holds to the once popular view that alluvial gold and gold nuggets are formed by growth in situ in the gravels from percolating goldbearing solutions. He defends this view especially on the ground of the crystalline character of much alluvial gold; he quotes competent authorities who deny this fact, but affirms it from his own experience. The author does not explain why, on this precipitation theory, nugget formation is so local, and why the nuggets are so constantly found just below the outcrop of reefs containing nuggety patches of gold. He

admits that the nuggets of Western Australia are derived from gold-quartz veins, and the evidence for the similar origin of the nuggets from Victoriawhich contains the most famous of nugget-yielding goldfields-seems to the writer overwhelming.

Another doubtful hypothesis advanced by the author is the absence of any undoubted, valuable preCretaceous placer deposit. He rejects, or quotes with apparent approval those who reject, the alluvial origin of the gold in various Mesozoic, Palæozoic, and Archæan conglomerates and sedimentary deposits; and he then argues that the absence of pre-Cretaceous detrital gold is due to the rocks having been lowered into a zone saturated with alkaline waters which removed the gold in solution and re-deposited it in veins.

Though many geologists may be disposed to differ from the author in some of his conclusions as to the formation of gold ores, they will be no less grateful to him for this valuable and trustworthy summary of the voluminous gold literature issued during the past twenty years. J. W. G.

SWINE IN AMERICA.

Swine in America. A Text-book for the Breeder, Feeder, and Student. By F. D. Coburn. Pp. xv+614. (New York: Orange Judd Co.; London: Kegan Paul and Co., Ltd., 1909.)

JUST

UST as it might be said of the British fat bullock that he has followed the turnip, so it might be said of the American fat hog that he has followed the corn, i.e. Indian corn. In the United States there are 56 millions of swine-there are only three and a half millions in the United Kingdom-and far more than half these are to be found in the great corn States which are drained by the Mississippi and its tributaries. Iowa comes first with 83 millions, and Illinois and Nebraska next with 4 and 4 millions. Altogether there are about eighty million pounds' worth of swine in the United States, the duty of which it is to convert corn and other crops and byproducts into more marketable commodities, and eventually to feed, not only the Americans, but also some part of the industrial population and the armies and navies of the rest of the world.

An industry so vast can do with many a text-book, and Mr. Coburn has produced one for those who breed, rear, and feed the raw materials for the American packing houses. Many experiments have been carried out in the States on the rearing and fattening of swine, and the gist of these is embodied in Henry's "Feeds and Feeding," which, however, is a book dealing rather with principles than with the details of management, and a book, therefore, for the student rather than for the farmer. Mr. Coburn's is a farmer's book. He has collected Henry's and many other data, and set them forth in such a way that the nutritive effect and economic value of every important feeding stuff and by-product is dealt with, whether these foods are fed separately or with others. The effects of bulky and succulent foods and of concentrates, and of these consumed separately and jointly, are fully considered. Thus, for instance, a farmer

having a lot of corn is told what proportion of alfalfa, or roots, ought to be fed along with corn to attain the best economic results. This part of Mr. Coburn's

book is valuable.

In the earlier chapters Mr. Coburn deals with the various races and breeds of swine in the States, and also with the principles of breeding; but, as may be inferred from the following quotation, although he writes at some length, he does not get much beyond the current nebulous ideas held by stock-breeders on these subjects:

"There exists in some sections of Old Mexico a type of 'hog' which is the product of crossing a ram and a sow, and the term 'Cuino' has been applied to this rather violent combination. The ram used as a sire to produce the Cuino is kept with the hogs from the time he is weaned. . . . The Cuino reproduces itself and is often crossed a second and third time with a ram."

IN the preface the authors state that this volume is based on the teaching of the Edinburgh school of pathology, where the first chair of pathology in the United Kingdom was founded, and as such we welcome its appearance. At the same time, we do not note any features particularly novel, either in the subject-matter or in its arrangement, and in some respects the book seems to be lacking as a text-book of general pathology. Thus the important factor of heredity in disease, and shock and collapse, are not even mentioned, and we do not understand why a discussion of the nature of gout and the chemistry of uric-acid metabolism "do not come within the scope of the present volume."

The opening chapter deals all too briefly with the cell in health and disease. An excellent summary of modern views on cell-structure and cell-division is presented to the reader, but the section on the chemistry of the cell is mainly occupied with the recommendations of the Chemical and Physiological Societies on protein nomenclature.

The chapters which follow deal respectively with general retrogressive processes, disturbances of the circulation, inflammation and repair, progressive tissue changes, animal parasites, and immunity.

An excellent account is given of fatty change, and modern views respecting it are succinctly stated. Lardaceous disease is similarly well treated, but we do not understand why authors will persist in employing the terms ‘waxy " and "amyloid" to designate it, for "lardaceous has the claim of priority; it is official in the "Nomenclature of Diseases" of the Royal College of Physicians, and the material present is universally known as lardacein.

The chapter on inflammation and repair gives all essential details on this important subject. The classification of tumours, admittedly a difficult subject, adopted by the authors is that advocated by Adami. This seems to us unnecessarily complex for the medical student and practitioner. The structure of tumours is given at some length, and the chief views on the

causation of tumours are summarised. As regards the. latter, one or two points brought out by recent research have been omitted. For example, the occur. rence of heterotype mitosis in malignant growths & referred to, but Bashford and Murray's criticism t Farmer, Moore, and Walker's work in this connectic does not appear, and in discussing the supposed sarc matous metamorphosis of carcinoma no mention made of the fact, which now seems certain, that it is the connective tissue stroma of the carcinoma whic is thus transformed, and ultimately overgrows the ca cinomatous elements. The vegetable parasites ar omitted, as these are dealt with in text-books of ba teriology, but an excellent and fairly full account's given of the animal parasites, protozoan and met Immunity is discussed in twenty-five pages and the essentials of the subject are conveyed to the reader.

zoan.

On the whole, the book may be regarded as a ver useful text-book of general pathology. It is excellent! got up, and a word of praise must be bestowed on the illustrations, 162 in number (also four coloured plates the majority of which are the work of Mr. Richar Muir, and as a rule depict very clearly the subject: they represent, though it may be questioned whether so many are really necessary, as they tend to distract the student from an examination of the actual specimens themselves.

(1) Der Bau des Weltalls. By Prof. Dr. J. Scheiner. Dritte, verbesserte Auflage. Pp. 132. (Leipzig B. G. Teubner, 1909.)

(2) Die Planeten. By Dr. Bruno Peter. Pp. 13(Same publishers, 1909.) Price 1.25 marks each. (1) THE series "Aus Natur und Geisteswelt" is we known. It consists of a number of little treatises, which men of science occupying prominent positions have attempted to explain in an accurate and comprehensive manner the results of past inquiries, and the position to which our knowledge has extended in various directions. In the former of the two specimens before us, Dr. Scheiner gives the substance of si popular lectures delivered in Berlin to a number high-school teachers in the course of which h attempted to describe so much of the universe as comes within the range of our telescopes. He endeavoured to bring home to his audience the magnificent scheme of distances on which the planetary and stellar sy~ tems are planned; he traced the detection of proper motion of the fixed stars, and showed how the sun's movement in direction and amount can be determine The phenomena of the sun are explained in some detail, preparatory to the examination of the spectr of stars, a subject which is discussed somewhat fully as might be expected from a member of the staff the Potsdam Observatory. Herein, as the auther points out, he is on the sure ground of observation But in his last chapter he approaches the more spec lative subject of the origin and constitution of the universe. The subject is handled with skill, and, notwithstanding the limited space to which the auther is restricted, he has succeeded in making his subjec both clear and interesting. We do not wonder that the little work has passed through three editions, for apart from that longing to satisfy an intelliger curiosity which appeals to so many, the material is put in a very attractive form, which should appeal t many readers.

(2) Dr. Peter has a simpler subject, in which the facts have been many times detailed, and he has litt scope for either originality of treatment or lucidity o arrangement. As the planets extend in order from the sun, so he must follow them from Mercury to Neptune A Vulcan is hinted at within Mercury's orbit, but the

hypothetical planet outside Neptune does not attract comment. Since the satellites of Jupiter and Saturn come under notice, more attention might have been given to the moon and to the phenomena of eclipses. The plan of the book, however, aims rather at the description of the surface than of the motion of the planets, though naturally the tale of the discovery of Neptune is told once again. It might seem that there is scarcely room for such a book, considering the number of popular works that are extant, but there is some difficulty in keeping even these works abreast of the time. As an example we may quote the sen[tence, "Bestimmt sieben, wahrscheinlich sogar acht Monde umkreisen Jupiter." Notwithstanding the recent issue, there is here opportunity for correction in the next edition.

Untersuchung und Nachweis organischer Farbstoffe auf spektroskopischem Wege. By J. Formánek, with the collaboration of E. Grandmougin. Pp. 252. Second edition. Part i. (Berlin: Julius Springer,

1908.) Price 12 marks.

THE first edition of this work appeared in 1901 in a single volume. In part i. of the new edition which is now before us, subject-matter to which only forty-two pages were devoted in the first edition has been elaborated and added to so largely that it occupies the whole of part i. The introduction deals with spectroscopic methods in general, but more particularly with absorption spectra of coloured solutions and the influence of solvents, concentration, reagents, temperature, &c., on the latter. Then follow chapters on the spectroscope, general observations on the relationship between colour, absorption, fluorescence, and constitution of coloured compounds and dyestuffs, and on the relationship between chemical constitution and absorption spectra of dyestuffs belonging to individual classes. The latter include di- and tri-phenylmethane dyestuffs, quinonimide dyestuffs, fluorindene and triphendioxazine, acridine dyestuffs, and anthraquinone dyestuffs. No mention is made in this part of the azodyes, or the dyes of the indigo group, while of natural dyestuffs only alizarin is mentioned. It is to be presumed, however, that these important classes will receive due consideration in part ii., which represents the practical part of the work.

Although a vast amount of work has been done by different observers on the absorption spectra of the organic dyestuffs, the information is so scattered as to be difficult of access to the ordinary individual, and this is probably the main reason why this important subject has hitherto not received the attention which it merits. There is, however, ample testimony that this particular application of the spectroscope is being more and more appreciated by the manufacturers of dyestuffs

on the one hand, and the users on the other. This is borne out by the fact that such an eminently practical body as the Société industrielle de Mulhouse has made a pecuniary grant to the author to enable him to publish the new edition. Prof. Formánek has made a life-long study of his subject, and a comprehensive and up-to-date book on this particular application of spectrum analysis, such as the present edition promises to be, would be much appreciated. It is to be hoped that the completion of the work will not be

long delayed.

well known that these properties, while still remaining additive, involve factors depending on the constitution of the molecule, e.g. method of linking, ringformation, &c., all of which should be taken into account in the calculation of the value of the particular property in the case of any given substance. It is the thorough-going application of this principle in the calculation of thermochemical constants, extended so as to include, not only the specific thermochemical values of double and triple bonds, but also the thermal value of the "strain" in ring-compounds and of the single bond in chain-compounds, that the book under review expounds. The author's method of calculation has already appeared in several articles published in the Chemical News, on which the present monograph is based.

The author's method will best be understood from the following:-Let H be the value of a hydrogen atom plus the link joining it to a carbon atom. Let C be the value of a carbon atom, not including the value of its valencies; let L,, L., L,, be the values of the single, double, and triple bonds respectively. Knowing the constants for four hydrocarbons, it is possible to calculate the value of the following:C+4H=a, 2H-L,=8, 4H-L2=7, 6H-L1 =8. These fundamental constants for carbon and

are the "

hydrogen. Moreover, the formula of any compound can be written in terms of these fundamental constants, and the theoretical value so obtained can then be compared with the experimental number.

This method the author has illustrated by the calculation of a large number of heats of combustion of substances belonging to different groups of compounds, and, with comparatively few exceptions, excellent concordance with the experimental numbers has been obtained. In this fact the method has its justification.

In an interesting section the author discusses also the relation between heats of combustion of ring-compounds and von Baeyer's strain theory, and he shows that in general there is perfect agreement. No simple relationship, however, has been obtained between the angle of deviation and the thermal equivalent.

The book is one which deserves and will no doubt obtain the attention of all who are interested in the relations between the thermochemistry of compounds and their chemical constitution; and the method of calculation is, moreover, one which will not improbably find application in the case of other physical properties of an additive character. It is an important addition to the literature of thermochemistry. A. F.

An Angler's Season. By W. Earl Hodgson. Pp. xii+ 299. (London: A. and C. Black, 1909.) Price 3s. 6d. net.

A BOOK from Mr. Hodgson is always worthy of the angler's attention, and " 'An Angler's Season is no exception to the rule. Dealing as he does solely with salmon and trout, and almost entirely with Scotch waters, the author's season begins in January and ends in October, and to each month a chapter is deal of sage advice, and some controversy. Early in allotted; throughout there is much good reading, a February Mr. Hodgson is already at issue with the dry-fly fisherman, and his attack on the "Hampshire method waxes furious, but he says nothing of those who fish with the dry fly in Aberdeenshire waters and find the method successful. Fault is also found with some anglers for their “habitual indifference to the weight of a basket" and their love of nature; surely an angler is no worse for also being a naturalist, or at least taking an interest in the natural history of fishes. A study of what naturalists have written would have shown the danger of Mr. Hodgson's theory that taking large fish only, and restoring all of

smaller size to the water, would have the effect of increasing the average weight of the stock of fish in three years' time, and would, we think, have prevented the red flesh of some trout being attributed to richer feeding rather than to a differently constituted menu. We think, too, that the theory set forth to account for the absence of a run of salmon in some rivers of the east of Scotland in May, June, and July is somewhat strange, and cannot be maintained in the light of our present knowledge of the salmon's lifehistory.

There are throughout the book numerous practical hints of value upon such subjects as flies and baits, and as to the time and place for fishing under various conditions of water and weather; in the last chapter there is also a most thrilling tale of a riverside adventure. The illustrations, reproduced from photographs, are excellent, but are almost invariably separated by many pages from the corresponding text, and there is a good index. L. W. 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.]

A New Departure in Seismology.

per

ON the photographic records obtained from British Association types of seismograph it has been noticed that when the films have been moving slowly (60 mm. hour) there have been slight thickenings in the trace, while if the recording surface has been moving quickly (240 mm. per hour) the line which ought to be straight is slightly wavy. These irregularities, which have hitherto received but slight attention, are so small that they may be easily overlooked. When the thickenings were first observed it was supposed that their existence was due to a flickering at the source of light or to some irregularity in the movement of the record-receiving surface. When, however, it was observed that these markings frequently occurred at the same time at different stations, as, for example, at Shide and Bidston, the conclusion was that they were due to movements of the ground, and might be the surviving phases of large movements with origins at a distance.

A very good illustration of this is given by comparison of the times of occurrence of the after-shocks which followed the earthquake of January 14, 1907, in Jamaica, with the times at which suspicious irregularities were found on the seismographic traces at Shide and Bidston. Between January 14 and July 5, 148 shocks were noted in Jamaica. Forty-three minutes after the occurrence of fifty-one of these shocks irregularities were found on the films at the stations mentioned. As forty-three minutes is the time we should expect a "surface" wave to travel sixty-seven degrees, or from Jamaica to England, the inference is that the slight irregularities represent movements which had their origin in Jamaica. Corresponding markings, with the exception of one at Göttingen on July 5, do not appear in the registers from European stations, which are not more than six or seven degrees farther from Jamaica than Britain.

Another instance of the recording of after-shocks are the markings seen on seismograms after the disaster which, on December 28, 1908, ruined Messina and Reggio. Between December 29 and January 30 at Mileto, forty miles from Messina, 225 shocks were noted. Eight of these reached the Isle of Wight, while on January 1 and 13 at Göttingen, Hamburg, and Laibach, only two were noted. The reason that so small a number travelled a considerable distance indicates that the originating impulses were weak. That a larger number should be recorded in Britain than at comparatively near stations is not so clear.

With smoked paper recording surfaces, whether the multiplication of recording levers be 10 or 200, a certain slackness in joints and elasticity of pointers prevents any record of motion being obtained until a certain amplitude of ground motion has been reached. With photographic

recording apparatus where a light source is far from recording surface, a thick line may obscure any min movement. These instruments are therefore unsuitable recorders of very small movements. This, at any rate, i been my experience.

The British Association type of instrument, properly adjusted and installed, does, however, pick these neglected movements-a result which is shown ver clearly in the registers for this year.

It seems to me that beneath observatories all over t world earth-messages may be passing every few minut but these are not recognised because instruments general in use are not capable of recording the same. To inves gate this possible new departure in seismology, old ty of instruments will have to be improved or adopted.

Shide, Isle of Wight, July 2.

new

JOHN MILNE

Tables of Bessel Functions.

A COMMITTEE of Section A of the British Association fo the Advancement of Science, appointed to undertake further tabulation of Bessel functions, is at present co sidering the advisability of unifying and completing t existing tables with the view of the publication of complete table of Bessel functions.

The committee would be glad of information as to ere. ing tables of Bessel and Neumann functions with a te or complex argument, in addition to the following, which the members are already aware :—

(1) Meissel's Tables (reprinted in Gray and Mathew treatise on Bessel functions) giving J(x) and J,(x) fr x=0 to x=155 at intervals of 0.01 [12 places]; also. table of the first 50 roots of the equation (x)=0 16 places.

(2) British Association Tables (1889, 1893, 1896 Repor giving (x) and 1,(x) from x=0 to x=51 at intervals. 0.001 [9 places]; also 1(x) to I,,(x) from x=o to x= at intervals of 02 [11 and 12 significant figures]; also table of J(xi) from x=0 to x=6 at intervals of 2 [9 places]. (Part of these tables are reprinted in Gr. and Mathews.)

(3) Tables of J,(x) in Gray and Mathews from n=0 n=60 and from x=0 to x=24 at intervals of un [18 places]. (4) B. A. Smith's Tables giving Y,(x), -Y,(x (log 2-y)J.(x)—Yo(x) and from (log 2-7)J (x) - Y1(x), x=0 to x=100 at intervals of 0-01 and from x=1.1 x=102 at intervals of o1 [4 places: error not exceedi 2 in the last place]. (Messenger of Maths., vol. xxv... 1897, and Phil. Mag., vol. xlv., 1898.)

(5) Aldis' Tables of I,(x), I(x), ́ K(x), K,(x) free) x=0 to x=11 at intervals of 0.1 [16 places]. (Roy. Sor. Proc., 1896 and 1899.)

(6) J. G. Isherwood's Tables of K,(x) to K,,(x) from x=0 to x=5 at intervals of 02 [5 significant figures (Manchester Lit. and Phil. Soc., vol. xlviii., 1904.)

The committee will be grateful to be allowed, through the medium of NATURE, to invite any readers who ar aware of the existence of tables of Bessel functions oth than the above to make known this fact.

Communications should be addressed to the secretary the committee, Dr. L. N. G. Filon, University Colleg Gower Street, W.C. M. J. M. HILL University College, Gower Street, W.C.

1:

Baskets used in Repelling Demons. IN the issue of NATURE published on May 27 M: Kumagusu Minakata inquires regarding the use of baskets in repelling demons in countries other than Japan. Calcutta, and I believe in other parts of India, it i customary when a new building is being erected to set up on the highest part of the scaffolding a pole, to the to. of which a round basket and a scavenger's broom are attached. The basket and broom are apparently recognised as emblems of the low-caste " sweeper, and therefore a being disgusting objects. They are supposed to ward er ill-luck from the building. Their use in this instance ma thus be compared to the use in many countries of obscen objects or gestures as a protection against malicious spirits or the evil eye. N. ANNANDALE.

Indian Museum, Calcutta, June 13.