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telephony there can be little doubt but that by the application of these two sciences he has effected a greater revolution in human affairs than by all his successes in the way of heavy engineering. He may "electrify" our railways, especially the suburban lines, to the great advantage of both the travelling public and the shareholder, but he is still only doing for us in another way what the mechanical engineer has already accomplished. He may harness the great waterfalls and transmit their power over hundreds of miles to localities at which it can be more easily utilised, but he is only saving Mahomet the trouble of going to the mountain. He may provide for us in the arc lamp and the glow lamp the most efficient means of producing artificial light, but he is only supplying us with an alternative to the cheaper productions of the gas engineers. But with telegraphy he has given us something entirely new-an art which, whilst actually annihilating distance, virtually annihilates time. So familiar have we become with the operations of the telegraphist that few probably ever realise how closely dependent upon them is every detail of modern civilised life. We speak of the twentieth century as being, or as promising to be, the electrical age, and we think of the railways, the lighting, and the development of power, whereas in reality it is the electrical age because of the telegraph and the telephone. If the vast network of thin wires which stretch over the civilised world like the threads of a spider's web were suddenly wiped out to-morrow, we should as suddenly realise with the non-appearance of the morning paper what it meant to be thrown back into the age before electricity.

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In spite of the enormous influence which telegraphy exercises in our daily life, we hear a great deal less about it than we do of a number of unimportant things. Few people write papers upon it. The Journal of the Institution of Electrical Engineers, originally the Society of Telegraph Engineers, will be found almost free from such papers during the past ten years, Fewer people write books. The reason is not far to seek. Every applied science passes through three stages-the stages of incubation, of growth, and of maturity. In the first stage the outsider hears little about it; some few who are specially interested in scientific research may be aware that some observations of the natural philosopher are being developed along lines that promise results of great practical utility. At length a point is reached when the practical value of the work becomes so self-evident that even the halfpenny paper realises it, and the world is provided with a new nine-days' wonder. From now begins the period of growth, during which publicity is excessive. Everyone talks about the new discovery. Everyone who can makes experiments in connection with it, and publishes his results in papers, and those who cannot afford the time to experiment write books on the subject. After a period more or less protracted public interest wanes, and is diverted, we will say, to a scandal of tinned meat, and, what is more important, the science, from being experimental and much talked of, becomes practical and much used.

In the art of telegraphy we see a science which reached, long ago, the last stage. If anyone wishes for a general idea of the extent of telegraphy at the present day let him read Mr. Herbert's book. Unless he is an expert, or studying to become one, he will probably realise more from the style in which the book is written than from the study of it in detail. He will see that here he is dealing with something which is firmly established, in which methods and apparatus have become almost stereotyped, and in which progress can only be exceedingly slow because everything is already so highly developed and because the interests which are vested in the methods now in use are so gigantic that only a revolution can warrant their overthrow. Mr. Herbert's book is full and concise, and a vast amount of information is condensed into its pages. At the same time it is simple, as befits a book intended for young students and dealing with a subject in which simplicity has been reached through complexity.

In the three books on wireless telegraphy before us we see good illustrations of what has been said above of the stage of growth of an applied science. Mr. White's book is a somewhat belated arrival, belonging properly to a few years back. It is purely descriptive, almost purely popular, and should have been written when the general public had a keen and living interest in the subject. Inasmuch as it describes the latest systems it has a certain claim to existence. But wireless telegraphy has almost reached the third stage, and before long we shall cease to hear anything more about it, and, taking it for granted, will concern ourselves only with grumbling at its cost. That it has not fully reached the final stages is sufficiently shown by Dr. Fleming's and Dr. Eichorn's books. Of Dr. Eichorn's book we can only say that we should have greatly welcomed its appearance had it not been for the almost simultaneous publication of Dr. Fleming's work. Dr. Eichorn was manager of the large experimental stations for Prof. Braun, and writes specially about the systems which have been developed by Slaby, Arco and Braun into the "Telefunken" system, which shares, we suppose, with the Marconi system the honour of being the most important and most practical systems yet developed. The book is well written, and combines with a good deal of description a careful investigation of the fundamental theoretical phenomena.

But in Dr. Fleming's book we have undoubtedly the one to be recommended to students specially interested in wireless telegraphy, and the practical development already attained warrants the existence of a certain number of such students. If technical education were organised in an ideal manner there would exist a professorial board the duties of which would be to prescribe exactly the literature which a student should and should not read. Such a body would allow anyone to write and publish books, and would not prohibit reading them until the tentative efforts of various authors resulted in the production of one or more books containing all the information on the subject which could be regarded as necessary and sufficient. Then they would say to the student:

You may read this and that book, but on no account are you to waste any time on any others; you may consult such and such original researches, but the remainder are useless. We have no doubt that this body would notify in the present instance that the student of wireless telegraphy must confine his attention to the books by Hertz and Dr. Fleming. We are not speaking of the student of electromagnetic waves. In Dr. Fleming's book is to be found a treatment of the subject which is exhaustive and thorough both on the theoretical and practical sides. It is a book which has been long wanted, and will be warmly welcomed.

One may notice, however, by a careful study of the book that wireless telegraphy practice is still to a certain extent tentative. The best methods are not yet decided upon, and methods differ because there is still much ignorance. But there are signs that the approach to more exact results is being made with the advent of apparatus based on wider knowledge and capable of allowing accurate measurements. Just as telegraphy needed the development of very special apparatus before full advantage could be taken of its powers, so wireless telegraphy calls for its own special apparatus. The process of development is necessarily slow, but in our present state of technical attainments it is sure.

It is quite evident from the perusal of the books before us that there is room in our complex civilisation both for ordinary telegraphy and wireless telegraphy. There are very few new discoveries which succeed in displacing old ones. We have room for many technical developments, and are capable of using all to their best advantages in the spheres for which they are particularly suited. For telegraphy over land there is little, if any, fear that wires will be displaced. There is little fear either that for communication between continent and continent the cable will give way to the overgrown “antennæ." Wireless telegraphy has found its special sphere in communication with ships, and soon will succeed in bringing us as close together at sea as we now are on land. When we consider that any man in any civilised country will be able to get into almost instant communication with any other, either on land or sea, we can realise something of the benefits conferred by telegraphy with wires and without.

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in the history of the germ-cells, and have neglected to inquire into the fundamental cause which unifies the whole. They have reached partial interpretations,. usually "artificial and teleological," of details, but a connected general theory is lacking. They have been like geologists interpreting the course of a river, and ignoring gravitation, The unifying secret is biomolecular addition," which seems to mean the power that the living molecule (whatever that may be has of adding to itself another molecule " so that the biomolecule resulting from the addition has double the number of atoms, and may, in consequence, divide into two biomolecules similar to one or the other of the added biomolecules. Thus a male biomolecule and a female biomolecule (identified with paternal and maternal biomolecules) may add together and then divide into two biomolecules which are either male or female. We do not profess to understand this. though the author assures us that biomolecular addition is "nothing but a chemical reaction of the greatest simplicity between the biomolecules constituting the genetic cells," and we regret that we do not understand it, for we are told that "it suffices to explain even in their minor details all the interesting manifestations accompanying the function of sexual reproduction." These are brave words, but the author's explanation" seems to us far removed from the present-day scope of biology, in Britain at least.

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The author cannot accept Weismann's theory of germinal continuity, believing, on the contrary, that the ancestors of the germ-cells become histologicall differentiated, like ordinary somatic cells, alon special lines of "monodic" development. certain epoch-" the genetic moment "-however, they come under the influence of special substances in the internal milieu, and are shunted back on a sort of return journey which brings them, or their de scendants rather, to or near their starting point of resemblance to the parental ovum from which they are by cell-lineage derived. If the germ-cells can return perfectly to the state of the original fertilised ovum, with its dual equipment of male and female biomolecules, then parthenogenesis may occur. But this complete return implies very favourable nutritivi conditions in the internal milieu, and, as a matter of fact, what usually occurs after the "genetic moment is a process of internal biomolecular addition as the result of which the male or the female biomolecules in the germ-cells disappear, and two kinds of genetic cells are differentiated (with female or male biomole cules respectively). Thus fertilisation is necessary to restore the integral constitution of the original parental ovum. "The primitive cause of sexuality and of fertilisation is to be found in the phenomenon of biomolecular addition." In a laboriously ingenious fashion the author uses his key to read the mysterious ciphers of maturation and fertilisation, and he finds that it unifies everything-hermaphroditism and parthenogenesis, secondary sex characters, and the rejuvenescence of infusorians. But we have not been able to use his key, and his distinctions between pro genetic and metagenetic parts of the body, neuter and sexual paragenetic cells, external and internal bi

molecular additions, are not readily borne in mind. We have not been more successful with a previous volume dealing with development, which explains that there is "one fundamental principle" controlling the detailed ontogenetic phenomena, namely, "the principle of monodic development." Though it is "of extraordinary simplicity, like all the principles of natural phenomena," we have failed to detect its luminiferous quality.

But as the author emphasises the fact that if his argument is to be appreciated there must not be "the least omission of any part of the book, even if it seems a superfluous repetition," and as he "has consecrated all his intellectual activity and all his scientific passion" to working out an interpretation which seems to him "to explain the fundamental phenomena of life on absolutely scientific principles," we feel bound, in fairness, to recommend the author's painstaking work to all biologists who may have the leisure and patience which a study of "Les Problèmes de la Vie" requires. Perhaps another requisite which we cannot pretend to possess is a clear apprehension of the biomolecule. J. A. T.

ECONOMIC ZOOLOGY. Report on the Injurious Insects and Other Animals observed in the Midland Counties during 1905. By Walter E. Collinge, M.Sc. Pp. 58+ xxxii figures. (Birmingham: Cornish Brothers, Ltd.,

Price 25.

1906.) MR. COLLINGE, in his third report on the in

jurious insects and other animals of the Midland counties, again deals with many varied subjects. The report is well illustrated, except for the figure of a weird bird and its egg supposed to represent a barn owl. Why a valuable page was wasted on such an unnatural production is impossible to understand.

One of the most interesting parts of the report is that dealing with "big-bud" in black currants, and the treatment of diseased bushes (pp. 6 and 7). In a Summary Mr. Collinge tells us that he "feels convinced that the application of lime and sulphur will keep this mite in check, and if the dusting or spraying is continued will entirely eradicate it." Later he tells us that the results have been checked by many large growers, and that they clearly point to the fact that "the application of lime and sulphur offers an effective remedy." He does not tell us how many times we have to dust or spray the bushes. That we know completely the life-history of the mite" is certainly not the fact; some dozens of points have yet to be found out.

An interesting account is also given of the plum Aphides (Hyalopterus pruni and Aphis pruni). Something is wrong, however, in the account of Aphis pruni, for the young coming from the winter eggs, which are very few in number, and hatch very early in the year, are not green. In early spring we find this Aphis as a large plum-coloured a large plum-coloured "motherqueen," and she produces green living young. The treatment recommended, namely, early spraying, is nevertheless most imperative.

Among other insects this useful report deals with we find notes on the pea and bean thrips, woolly aphis, currant-shoot moth, raspberry moth, cockchafers, furniture beetles, and book-lice. There are also short accounts of the lilac Gracilaria and the larch Coleophora. The abundance of eel-worms during the past year is also dwelt upon, and a list of woodlice found in the Midlands is given.

Amongst so much of value, such as the account of the snow-fly (Aleyrodes vaporarium, p. 22) and the larch and spruce chermes (p. 14), that this report contains, we are sorry to see some wrong statements being carried forward. For instance, on p. 23, caustic alkali wash is still recommended for mussel scale in winter. Recent work has shown that it has no effect at all, even when used at treble the normal strength.

A few pages are devoted to the subject of the preservation of wild birds, illustrated by figures from the Board of Agriculture and Fisheries leaflets. There is also a short appendix dealing with the employment of hydrocyanic acid gas and bisulphide of carbon.

This report, like its predecessors, is one of much interest, but some of the remedial measures for such things as wire-worm and " big-bud" must surely not be taken too seriously by agriculturists.

FRED. V. THEOBALD.

THE FEELING FOR NATURE.

The Development of the Feeling for Nature in the Middle Ages and Modern Times. By Alfred Biese. Authorised Translation. Pp. vi+376. (London: Routledge and Sons, Ltd., 1905.) Price 6s.

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NATURE in her ever-constant, ever-changing

phases is indispensable to man, his whole existence depends upon her, and she influences him in manifold ways in mind as well as body." Such being the relation of nature to man, as set forth in the introduction, it has been the author's endeavour to trace in this volume the development of human thought in regard to the phenomena of nature from the introduction of Christianity downwards, in the same way that was done in a previous volume for the time of the Greeks and Romans. This has been done mainly by the study of writings, both in prose and poetry, in which natural phenomena, whether connected with scenery, weather, birds, or flowers, are spoken of with admiration. That the task of writing the book was a difficult one is freely admitted by Prof. Biese, and it is scarcely to be wondered at if at the end the book strikes the reader as somewhat less attractive than he would naturally expect from the title.

The book is largely made up of quotations, and many of these quotations do not, after all, prove very much. Then, again, as we approach recent times the quantity of literature at a writer's disposal tends to become for practical purposes infinite, and in such circumstances anything might be proved by choosing suitable quotations. Again, in quoting poetry as an indication of popular feeling at various times it must not be forgotten that poetry is, from the very nature of things, essentially conservative, so

that the poetry of one age necessarily reproduces the thoughts and modes of expression of previous ages. It thus appears that the method of treatment which undoubtedly was admirably adapted to the study of the Greek and Roman period becomes less and less satisfactory as the present day is approached. The early chapters are, therefore, by far the most interesting. They deal with the effects of Christianity in turning man's thoughts from the things of this world to spiritual matters, and with the revival of the feeling for nature among the German races, who, living in a northern climate, were naturally led to appreciate and value the beauties associated with the coming of summer. But it may be reasonably urged that evidence of later-day developments of the feeling for nature should be sought in science rather than in art, in the interest taken in the study of natural phenomena rather than in the recantation of praises of sunshine, sea, and the nightingale's song.

It is fairly certain that if some readers do not find this book as interesting as they expect, there will be others who will enjoy its perusal more than this review suggests, and we may safely apply to Prof. Biese the Yorkshire quotation, "He did his best and he couldn't

do owt else."

OUR BOOK SHELF.

A Handbook of York and District. Prepared for the Seventy-fifth Meeting of the British Association for the Advancement of Science, 1906. Edited by Dr. G. A. Auden. Pp. xvi+365. (York: J. Sampson, 1906.)

workers. In most cases, unfortunately, the exigences of space prevent much more than lists of species, but it can be safely said that this portion of the handbook forms an epitome of the natural history of the dis trict. Mr. J. E. Clark brings the volume to a close by some meteorological notes.

There are three maps sent with the volume, all of
which are excellent. It was a happy thought to re-
produce Skaife's archæological map of York, and
with the help of the Ordnance Survey department a
is produced. The third is obviously principally for
really charming map of the greater part of Yorkshire
the use of the geological section, and is coloured so
as to show the glacial lakes, moraines, &c.
T. S.

Bacteria in Relation to Plant Diseases. By Erwin
F. Smith. Vol. i. (Washington, D.C.: Carnegie
Institute, 1905.) Pp. xii +285.

AN authoritative account of bacterial plant diseases
has long been a desideratum, and no investigator
more competent than Mr. Erwin Smith, of the U.S.
Department of Agriculture, who has himself made
important original contributions to the subject, could
be found to undertake such a task. The bacterial
diseases of plants are, however, only incidentally
mentioned in this, the first volume of the work, which
is mainly devoted to methods of investigation and to
a bibliography of the general literature of bacterio-
logy, exclusive of plant diseases. As a guide to
general bacteriological methods we know no better.
though, as it is a preliminary to plant bacteriology,
methods specially applicable to pathogenic organisms
attacking men and animals are necessarily not to
be found. Sterilisation, the preparation of culture
media, methods of infection, the investigation of
chemical products, keeping of records, and equipment
of the laboratory are all dealt with very fully, explan-
atory figures being used liberally. A considerable
section is also devoted to an account of photomicro-

THE handbook which has been prepared for the benefit of those attending the forthcoming meeting of the British Association at York will be found to be exceed-graphy. The difficult question of the nomenclature ingly useful. The volume is neatly bound and printed on suitable paper, is of the size now usually adopted by the local committees, and has a most appropriate design on the cover. Undoubtedly most of the members attending the York meeting will take an interest in the relics of the past with which this ancient city abounds. It is natural, therefore, that by far the greater portion of the book should be devoted to a description of the various antiquities from prehistoric to mediæval times. The editor, Dr. Auden, describes the prehistoric remains, Mr. H. M. Platnauer refers to the relics of the Roman and Danish occupations, and other writers continue the

story.

and classification of bacteria is critically discussed at considerable length, and forms an excellent summary of the whole subject. At the end of the volume a number of useful formulæ for stains, etc., is collected, and the bibliography, which extends over sixty-four pages, and index complete the work. The volume is excellently illustrated with thirty-one plates and 146 figures in the text. We congratulate Mr. Smith on this, the first, though perhaps the easier, portion of his task, and shall await the appearance of the next volume with considerable interest.

R. T. HEWIEIT.

Outlines of Zoology. By Prof. J. A. Thomson.
Fourth edition, revised and enlarged. Pp. xix+850
(Edinburgh and London : Young J. Pentland, 1900
Price 158.

The second part of the volume, which is restricted to 100 pages, contains an account of the geology, botany, zoology, and meteorology of York and district, and, as might be expected from the space THIS book has very great positive merits and very allotted, this part of the work is much more con- slight defects. Though it is packed with facts, and densed, and is not so readable as the earlier portion. can be recommended to students preparing for exThe Rev. W. Johnson describes the geology of the aminations, vet it is never dull, Prof. Thomson de district in a chapter exceedingly brief, possibly due scribes animals, not as corpses, but as living creatures to the fact that “the geology of York is, in one with interesting habits that depend largely on their sense, of the simplest kind." Dr. W. G. Smith, of structure. The method leads to expansion, and vet the Leeds University, gives an interesting general this excellent zoological text-book is a single royal survey of the botanical features of the district. This octavo of hardly more than eight hundred pages. chapter is particularly appropriate in view of the lead-Though our author, to use an American term. ing part being played by Dr. Smith and his colleagues "enthuses" his readers, he does not waste words in Yorkshire in reference to botanical survey. Lists over it. of flowering plants, algæ, fungi, Hepaticæ, Sphagnaceæ, Musci Veri; mammals, birds, reptiles, amphibians, fishes, beetles, butterflies, moths, and land and fresh-water shells are given by various York

In his general survey in the first chapter he begins with monkeys, as being the animals most like man and works down to the Protozoa. In the body of the book, reversing the order, he proceeds from the lowest

to the highest. This is an ingenious compromise between two methods each of which has something to recommend it. The early chapters, that deal with the functions of animals, the modern conception of protoplasm, the elements of structure, reproduction, the evolution of sex, and heredity are particularly good. The chapter on palæontology is, owing to the necessary limitations, far too short for the subject, but a table makes clear the order in which the different classes of animals appeared upon the earth. When we come to the body of the book we notice, as in the opening chapters, the remarkable clearness of the style; and though morphology is in no way neglected, yet some room is always found for the description of the habits of the animals in question. For instance, there are some eight pages devoted to the habits and functions of birds, their modes of flight, their courtship, their nests, moulting, diet, migrations.

One or two minor points may now be mentioned that seem to be open to criticism. Plants and animals, Prof. Thomson says, "represent the divergent branches of a V-shaped tree of life." But plants originated before animals; the nature of their food proves this beyond a doubt. Animals we must look upon as a branch from the primitive vegetable stem. The account of the Hydromedusæ would be much better for an illustration-a figure of a hydroid with the Medusa of the alternating generation or of Tubularia with its Actinula. Such additions would, of course, increase the bulk of the book, but the figure of a frog (p. 560) is superfluous, since everyone knows what a frog is like. Again, the process of natural selection is easily intelligible without Fig. 378.

F. W. H. Animal Heroes; being the Histories of a Cat, a Dog, a Pigeon, a Lynx, two Wolves, and a Reindeer. By E. T. Seton. Pp. 362; illustrated. (London : Archibald Constable and Co., Ltd., 1906.) Price 6s. net.

MR. SETON has always something fresh and interesting to tell his readers, and in the present beautifully illustrated volume breaks new ground in attempting to reveal some aspects of the strenuous side of the lives of animals, both wild and domesticated. Every one of the stories, we are told-although of course amplified and set out with the picturesque surroundings the author knows so well how to portray-is founded on the actual life of some individual bird or quadruped; the biography of the lynx being based on the author's own backwood experiences. Where all is so good, fresh, and entertaining, it seems almost invidious to select one portion of the book for special commendation. To our thinking, however, the almost pathetic story of "Arnaux," the homing-pigeon, is far ahead of the rest in sustained interest; but some may prefer the history of the tame wolf, while to others, again, the narrative of the wild reindeer may appeal more strongly. Alike to young and old the book may be heartily commended as an excellent example of the best style of animal biography. R. L.

Some Facts about the Weather. By William Marriott. Pp. 32. (London : Edward Stanford, 1906.)

Price 6d.

LETTERS TO THE EDITOR.

[The Editor aoes 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.]

Osmotic Pressure.

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PROF. KAHLENBERG'S letter published in NATURE July 5 shows that, as so often happens, the controversy about osmotic pressure is based on a difference in meaning assigned to that term.

We may adopt what now appears to be Prof. Kahlenberg's conception, and regard the osmotic pressure of a solution as a real experimental pressure reached with some actual membrane in certain practical conditions. Such a definition gives us a conception of great interest and importance, especially from a physiological point of view. But unfortunately it has no bearing on the thermodynamic theory of solution-or the allied theories of fusion and evaporation-which apparently Prof. Kahlenberg still wishes to attack by its means, after he has insisted that "the formation of crystals from a solution, or the concentration of a solution by evaporation are not osmotic processes.' Of course they are not osmotic processes in Prof. Kahlenberg's sense of the term. But the theory of fusion and evaporation, which, as I pointed out in my letter published on May 31, has been verified experimentally in the case of the depression of the freezing point to an accuracy of nearly one in a thousand, depends on the hypothetical separation of solvent by some ideal and perfect semi-permeable process.

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It is such considerations as these that demand the other conception of osmotic pressure, which, suggested no doubt by Pfeffer's experiments on osmosis, has now, in accordance with the usual course of development of the concepts of physical science, come to possess an ideal significance, towards which the actual experimentally measured quantity can but tend as the experimental conditions approach the ideal state postulated in the theoretical definition.

Defining osmotic pressure as the hydrostatic pressure needed to keep a solution in equilibrium with its solvent across an ideally perfect semi-permeable membrane, we obtain a conception, possibly of less chemical and physiological importance, which nevertheless enables develop a thermodynamic theory of solution; and this theory has been verified experimentally in cases where we have reason to suppose that the actual conditions approach the ideal.

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ception of osmotic pressure has occasioned trouble in other It would be well if a new name could be applied to osmotic pressure when used in one or other of its meanings; but I suppose that each side in the controversy would insist on the rights of possession and customary usage. Hence I would suggest that, at the cost of some complexity of nomenclature, one of the two meanings should be emphasised as experimental osmotic pressure" and the other as thermodynamic osmotic pressure.' Prof. Kahlenberg remarks that in creating the theory of electrolytic dissociation, the actual phenomena of electrolysis have played a minor part,' and wishes thus to invalidate my statement that "the theory rests on electrical evidence, and by such evidence it must be tried." I can hardly believe that Prof. Kahlenberg would wish seriously to commit himself to the opinion that the historical train of ideas by which a given hypothesis may have been reached necessarily supplies the only (or even the best) logical basis for its support. We do not always doubt the stability of our houses because it has been necessary or convenient to remove some of the scaffolding used in their construction.

It is true that the abnormally great osmotic pressures and freezing-point depressions of electrolytic solutions

This pamphlet supplies just the information about meteorological phenomena likely to be useful to the general public. The instruments in use in climatological stations are enumerated, and the determining originally suggested that the molecules of their solutes

factors of climate are explained in order. The booklet should be the means of stimulating interest in the scientific study of weather.

were dissociated; but such observations clearly can give no information on the electrical state of the dissociated structures. A valid test for an electric ion must depend on some electrical property, such as motion in an electric field.

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