interest by meteorologists, as not only model monograms of the subject discussed by them, but as further developing and occasionally opening up certain lines of inquiry which lead to practical applications of the science. In these respects the Report for 1873 is the best, as well as the most suggestive. Its outstanding feature is the discussion of the deficient rainfall of the Presidency during 1873, so disastrous by the famine which followed it; and the developing in the course of the discussion of a principle which, if confirmed by future observations, "will enable us to some extent to forecast our [Indian] seasons, or at least to speak with some confidence to their probable character for some months in advance."

The sum

From the increased number of stations now in connection with the department, and from the additional data obtained from the meteorological superintendents of the Governments of Ceylon, the Upper Provinces, Central India, and Berar, it is possible to form a conception of the geographical distribution of pressure, temperature, rain, &c., over one-half of India and its seas. maries of all the observations made over the region during the past seven years form an admirable feature of the Report. We very cordially join in the hope expressed that the observations which have been made in the Presidencies of Bombay and Madras will in future be accessible, and that those made in the Punjâb will be put on such a footing as to be trustworthy and comparable. As regards the last-named region, in all the annual reports we have seen (down to 1870) the barometric observations are given uncorrected for tenperature and unaccompanied with the readings of the attached thermometer! When, on making the annual survey of the meteorology of India, the north-west, west, and south of the country can be included, it will be possible to write the history of the two monsoons of the year, and probably to point out the determining causes of their irregularities.

"The principal meteorological characteristics of the year 1873 were an excessive temperature, in Oude and the North-western Provinces more especially; an unusually low pressure of the atmosphere in the same region, and probably also in the south-east corner of the Bay of Bengal, while in Eastern Bengal pressure was persistently high; great unsteadiness in the winds, indicating the predominance of local causes in affecting the air currents, while the normal monsoon current from the south-west set in nearly a month later than usual, and ceased nearly a month earlier; lastly, a general deficiency of moisture in the atmosphere, as is betokened both by the hygrometric observations, the comparative absence of cloud, and the great deficiency of rainfall."

The usual characteristics of the Indian summer monsoon, based on the past seven years' observations, are thus stated :—

"In ordinary years the winds of the south-west monsoon blow, on the one hand from the Arabian Sea, on the other hand from the Bay of Bengal towards a line lying to the south of the Ganges, at no great distance, and parallel to that river. A barometric depression begins to appear in or near this region in April, and by the time the rains set in in June it is well established; the pressure decreasing along it from east to west where this trough, as it may be termed, merges in the great barometric depression of the Punjâb and the Bikaneer Desert. To the south of this line the winds from the Arabian Sea blow across the Central Provinces, chiefly from the west. the north of it, those from the Bay of Bengal, turning

Το

with the Gangetic Valley, blow in an opposite, or easterly, direction, their line of meeting being along this trough." Bengal being thus dependent, as regards its rainfall, on the aërial current which blows from the Bay of Bengal up the valley of the Ganges, it is evident that whatever weakens this current or directs it to the northward will have a serious influence on the rainfall. Now, in 1873 the trough described above did not occupy the usual position to the south of the Ganges, but a position considerably to the north-west, in Oude and Rohilcund, immediately under the hills. A change in the direction of the wind necessarily followed this change in the position of the area of lowest atmospheric pressure; and in strict accordance with the now well-known relation of wind to pressure, there was an unusual prevalence of westerly winds over the greater part of Bengal during June and July, and the rainfall consequently was deficient.

The observations made in the Andaman and Nicobar Islands show the existence of a barometric depression over the south-eastern portion of the Bay of Bengal, the effect of which would be to deflect a large portion of the monsoon current of the Bay of Bengal towards Sumatra and the Tenasserim and Burmah coasts. Thus, then, the monsoon current, on which Bengal is dependent for its rainfall, was not only deflected northward from its usual track during 1873, but was also weakened in force by being partially drained away to the south-east in the direction of Burmah.

In the examination of the rainy seasons of 1868, 1869, and 1873, Mr. Blanford has the merit of first drawing attention to the existence of local and persistent variations of pressure, which appear as a local exaggeration or partial suppression of the great annual variation-the pressure remaining for many months, sometimes through two or more consecutive seasons, either higher or lower than the average, relatively to other parts of the country, over a more or less extensive track. It is to these persistent irregularities in the distribution of atmospheric pressure that the irregularities in the distribution of the rainfall must be ascribed, and it is to the further in

vestigation, by future observations, of the characteristic feature of persistency in this class of barometric variations that we look with hope to the realisation of a great triumph awaiting meteorology, viz., the prediction, for some months in advance, of the general character of the coming seasons of India, and thereafter a gradual extension of the principle to other countries.

As regards the humidity, the only data of observation published in the Report are the dry-bulb observations. To these are added the computed values for the elastic force of vapour and the relative humidity. In future issues of the Reports we should recommend that the wetbulb observations be also published. In a country of such extreme climates as India, it is eminently desirable to have the whole observed facts relative to the humidity before us, particularly since, from the present defective state of our hygrometric tables as regards dry hot climates, computed values can be regarded only as rough approximations. In estimating the state of the sky, a clear sky is entered as 10, and a sky comIt might be well in pletely covered with cloud as o. future to adopt the recommendation of the Vienna Meteorological Congress on this head, by which a clear sky is

10.

entered as o, and a sky completely covered with cloud as The number of days at the various stations at which" a measurable quantity of rain fell," are given in Table xxx. The exact amount of rain constituting a rainy day should in future be stated. In Great Britain only those days on which at least oor inch falls are regarded as "rainy days." We are glad to see that Symons' gauges (5-in. diam.) are adopted--this being the gauge best suited for general introduction-and that the height is a foot above the ground.

We have long been convinced that for a first satisfactory scientific discussion of some of the more difficult problems of the science we must look for the data of observation to India, with its splendid variety of climates, exposures, and abrupt mountain ranges and isolated peaks. The chief of these questions are, the variations in the daily march of temperature as dependent on season, latitude, height, and situation, both maritime and inland; the hourly barometric fluctuations (of which so little is really known), particularly as influenced by strong insolation, vapour, cloud, aqueous precipitation, and height either on extended plateaus or on hills rising abruptly from the plains; and the vital question of atmospheric humidity, to put which on a proper footing as regards hot dry climates, laboratory experiments being all but worthless, recourse must be had to extensive observations and experiments conducted under such conditions as are presented by the scorching climate of the Punjab. In the further development of Indian and general meteorology, the establishment of a Physical Observatory in the Punjab is urgently called for, as being, in truth, indispensable for the prosecution of these and other physical researches.

OUR BOOK SHELF

"On Flowers with Simple Pistils," "On Flowers with Compound Pistils," "On Flowers with Apocarpous Fruits," " ," "On Flowers with Syncarpous Fruits," and "On Stamens and the Morphology of Branches." To each chapter is prefixed a list of specimens which will be required to enable the student to follow for himself the writer's analysis; the descriptions are given in an extremely easy and lucid style, a few of the commonest scientific terms-but as few as possible-being gradually substituted for the colloquial English phrases at first employed. A sufficient acquaintance having then been obtained with the morphology of the more conspicuous organs, and their functions at the same time explained, the phenomena of nutrition, respiration, and fertilisation, and the structure of tissues, are described in chapters "On Fertilisation," "On Seeds," "On Early Growth and Food of Plants," "On Wood, Stems, and classification, to which is appended some useful tables Roots," and "On Leaves." A chapter is then given to of the characters of the more important orders; and this is followed by two or three chapters devoted to a few of the more important natural orders, and intended to serve as an introduction to the mode of naming plants. The employed in the work itself are explained in an appendix, most commonly used technical terms which have not been in which the wants of students preparing for the University Local Examinations have been kept in view.

The mistaken plan on which many botanical text-books have been compiled is so largely answerable for the horror in which the subject is held by candidates for examination who endeavour to cram facts and technical terms in an incredibly short space of time, without an attempt at practical work, and in the end fail miserably, that we cordially welcome an attempt to place the study on its true footing. We entirely concur in the view of the writer, that to this false method is due the fact that "Botany is so often stigmatised as a dry, uninteresting study;" an opinion which would speedily disappear were her mode of instruction in general use in the family and the school. Mrs. Kitchener's "A Year's Botany" seems to us admirably adapted for the purpose which she had in view in publishing it, and we heartily desire for it a large circulation. A. W. B.

Dental Pathology and Surgery, By S. J. A. Salter,

F.R.S. (London: Longmans, Green, and Co., 1874.) THERE is much in dental surgery besides the simple extraction of teeth, and it is to the consideration of the science of dental pathology that Mr. Salter devotes most of the work under notice. The introductory chapters treat shortly of structure and function, development being left out of consideration. An excellent diagram explains the relation of the tongue to the different parts of the mouth during the pronunciation of the various letters of the alphabet, which latter is arranged on a physiological basis, dependent on the situation of the point of closure by which the sound is produced, upon the completeness or incompleteness of the closure, and upon whether the breathing is soft or aspirate. To the purely physiological student the chapter on irregularities in the position and union of contiguous teeth will be of particular interest; as will the instances given of defects in their number depending on hereditary causes, and on alopecia; to which we may add the peculiar deficiency always connected with the excessive development of hair over the face, as in the Russian man and child who so recently visited this country. The differentiation off from pure surgery of a class of tumours which, before Mr. Salter's investigations, were considered to belong to the bones themselves, and which, as odontomes, are now known to be composed of secondary dentine, will be specially instructive to the pathologist, as will the question of reflex nervous phenomena, such as partial paralysis and blindness, from the irritation of a diseased tooth. A full and very instructive account is also given of "phosphorus

disease," which attacks in so painful a manner the manufacturers of lucifer matches, and which can be so completely obviated by the employment in their construction of red instead of ordinary phosphorus, because the former does not give rise to the formation of acid fumes when exposed to the air, and therefore does not attack the mouth and teeth. There is one subject on which we have looked, but in vain, through this volume for information it is for the explanation of how it is that toothdisease and civilisation so unfortunately go hand in hand. The work will be found of special interest to all students of surgery.

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. No notice is taken of anonymous communications.]

Deep-sea Researches

WHEN Prof. Wyville Thomson published his recent volume giving the results of the deep-sea researches conducted by himself and his colleagues, Dr. Carpenter, Mr. Jeffreys, and others, he also gave a sketch of the history of the subject; but he made no mention of my memoir on the Microscopic Organisms of the Levant Mud, published in 1847 in the Transactions of the Literary and Philosophical Society of Manchester, though this memoir had been referred to from time to time by Dr. Carpenter, Messrs. Parker and Rupert Jones, and others, and was, next to Ehrenberg's discovery of the microscopic structure of chalk, the starting-point of all these deep-sea investigations. It was the first to call attention to the existence of foraminiferous deposits in the sea, and to insist upon the organic origin of all limestones except a few freshwater Travertins, in opposition to the theory of chemical deposits that had previously been advocated in the works of Phillips and other geologists. I do not care very much about these questions of priority of observation, but since Dr. Wyville Thomson's article in NATURE, vol. xi. p. 116, dwells largely upon another point, which was also brought prominently forward in my memoir, I think it worth while preventing a repetition of the oversight, because the two subjects referred to, viz. the foraminiferous origin of calcareous deposits, and the subsequent modification of such deposits by the agency of carbonic acid gas, now prove, as I long ago insisted that they would do, two of the most important factors in the solution of the problem of the nature and origin of deep-sea deposits. Dr. Wyville Thomson, in the article in question, points out that extensive areas of the deep-sea bottom are now occupied by a reddish earth, and he has arrived at the conclusion that this earth is a residue left after all the calcareous Globigerina and other such elements have been removed by the solvent action of carbonic acid accumulated in these deep waters. In my memoir I arrived at the same conclusion from the study of the marine Tertiary deposits, containing Diatomaceæ, of Bermuda, Virginia, and elsewhere. Í may perhaps be permitted to republish the following extracts from that memoir, since it is not now readily accessible to all the numerous naturalists who are interested in this question :

"In the recent deposit of the Levant we have generally an admixture of calcareous and siliceous organisms. In some locali. ties the latter are more sparingly distributed than in others; in a few instances they are almost entirely absent. The same admixture occurs in the recent sands from the West Indies. The soft calcareous mud from the bottom of the lagoons of the Coral Islands contains a considerable number of similar siliceous forms, and corresponding results have been obtained in most of the marine sediments from various parts of the globe, examined by M. Ehrenberg.

"On the other hand, the infusorial deposits of Bermuda and Virginia are altogether siliceous. Not one calcareous organism exists. The siliceous forms comprehend the majority of those which I have described from the Levant, many of them being not only similar but specifically identical, and the manner in which they are grouped together in these distant localities indicates something more than mere accident. Indeed, we want nothing but the calcareous structures to render these Myocene strata perfectly analogous to those now in process of formation both in the Mediterranean and in the West Indian seas.

Are

these siliceous deposits, so void of any calcareous organisms, still in the condition in which they were originally accumulated? or were they once of a mixed character, like those of the Levant, having been subsequently submitted to some chemical action which has removed all the calcareous forms, leaving only the disposed to adopt the latter opinion, for several reasons." siliceous structures to constitute the permanent stratum? I am

After showing the resemblance between the residue left after treating certain substances with nitric acid, and the diatomaceous deposits, I proceed to say :

"Such deposits, in these present conditions, stand out as anomalies in the existing order of oceanic phenomena, and have nothing resembling them except the local freshwater accumulations which occur in various places. Between these, however, no real analogy exists. It must not be forgotten that the Virginian deposit can be traced for above two hundred miles; and, being marine, would doubtless be mixed up with such marine products as were likely to occur along so extended a line. The only recorded instance with which I am acquainted, that exhibits the slightest resemblance, is furnished by M. Ehrenberg, in his examination of materials brought home from the south pole by Dr. Hooker. Some pancake ice, obtained in lat. 78° 10', long. 162° W., when melted, furnished seventy-nine species of organ. isms, of which only four were calcareous Polythalamia, the remainder being all siliceous. But even this example, remarkable as it is, does not supply us with any real parallelism. The deposits in question have never yet exhibited a single example of a calcareous organism."

After referring to the European greensands, I continue :"Nature furnishes us with an agent quite equal to the produc tion of such effects as we are at present acquainted with. This is carbonic acid gas in solution in water. Mr. Lyell has already availed himself of the instrument to account for the subtraction of calcareous matter from imbedded shells, as well as for some of the changes that have taken place in the structure and compo sition of stratified rocks . . . It is easy to conceive that whilst these strata were in a less consolidated state than at

present, they might be charged with water containing carbonic acid gas. This would act as a solvent of the organic atom of lime until the acid was neutralised."

After venturing upon these conclusions in 1847, not as long series of investigations carefully worked out, I need mere speculative guesses, but as the deliberate result of a scarcely say how intense was the interest with which I read Dr. Wyville Thomson's observations, which so thoroughly sustain and confirm the accuracy of mine. My conclusions were wholly derived from the microscopic observations of earths and rock specimens which I compared with the few examples of foraminiferous ooze with which I was then familiar. The Challenger researches now show us how exten sively the conditions described in my memoir have prevailed; a fact which could not have been ascertained before the machinery having arrived at them in a decided or definite manner when the for deep-sea exploration attained to its present perfection. But materials for doing so were much more scanty than they now are, and when no one except myself and the late Prof. Bailey of West Point were giving much attention to the subject, I think I am justified in wishing the fact to be placed on record. Owens College, Dec. 12 W. C. WILLIAMSON

Origin of Bright Colouring in Animals THE origin of the bright colouring of flowers, through natural selection effected by insects, appears to me one of the strongest points of the Darwinian theory. But I think the ongin of the bright colouring of many animals, especially birds and insects, is on the contrary one of the greatest of its difficulties. Darwin accounts for it in most cases by sexual selection-the most beautiful males being the best able to obtain mates and to leave offspring.

In the way of this theory there are three very serious difficul ties, which I think have not been dwelt on as they deserve.

1. Before special coloration could arise as a specific character, the colours must have been variable; for selection can work only when it has variation to work with, and it appears incredible that such a cause as sexual selection could ever give them any great degree of fixity. But the bars and spots on the wings of birds and butterflies are, as a rule, perfecily definite, and not more variable within the limits of the same species than any other part of the organism. This difficulty does not apply in the same degree to the origin of the coloration of flowers through

tural selection by insects, because the spots and streaks of owers are much less sharply defined.

2. Why is ornamental colouring, as a rule, confined to the ale? If the love of beauty is an animal instinct, why, on arwinian principles, is not beauty developed in the females, the ost beautiful females being the most likely to obtain mates and ive offspring? I speak chiefly of birds.

3. Is there any reason to believe that the female has any choice power of selection whatever? I think that what evidence we ve goes to prove that she is passive: and certainly this opinion supported by the very general fact of the males fighting for the ssession of the females.

If the love of beauty is an animal instinct, then Darwinian inciples would require that the struggles of the males for the ssession of the most beautiful females should develop beauty the females by natural selection. But we see that the contrary what takes place-beauty is developed in the male, the hting sex.

Were a Darwin among birds to watch the ways of the human ce, he would probably feel certain that the love of dress and nament among women is altogether due to a desire to become ractive to men; and he would think those naturalists unsatistory, and perhaps mystical, who guessed the truth, that the re of ornament is a natural and healthy human instinct, not nfined to either sex or to any age, but stronger in youth than age, and stronger in woman than in man.

Old Forge, Dunmurry, Co. Antrim

JOSEPH JOHN MURPHY

Psychology of Cruelty

THERE is a passage in Mill's recently published essay "Nature" which well merits the attention of evolutionary ychologists. It is as follows :-"Again, there are persons who e cruel by character, or, as the phrase is, naturally cruel; who ve a real pleasure in inflicting, or seeing the infliction of pain. his kind of cruelty is not mere hardheartedness, or absence of y or remorse; it is a positive thing; a particular kind of luptuous excitement. The East, and Southern Europe, have orded, and probably still afford, abundant examples of this ious propensity." (Page 57.)

I

Now, I think that this hateful propensity" is of more comon occurrence than even Mr. Mill here gives it credit for. deed, I doubt whether anyone is entirely devoid of it, although, course, everyone who is sufficiently advanced in moral culture admit of the subordination of the baser instincts to the higher, s been more or less successful in "starving it by disuse." lieve, in short, that this propensity must be regarded as one the primary instincts of our nature, although, like other stincts, it varies in its original intensity in different individuals, id is further differentially modified by the various influences of ucation. The nature of this instinct is well expressed by Mr. ill in the above-quoted phrase, “a particular kind of volup ous excitement." This, I think, supplies the reason why it is, a rule, of stronger development in men than in women, and hy, as Mill observes, it is of most frequent manifestation in arm climates. It is also worth observing, that although thus sin to the amatory passion, it is of much earlier growth in the le-history of the individual. Indeed, childhood and youth are, civilised society at least, the seasons when its presence is ost conspicuous; in consequence, I suppose, of the restraining ower which reflection subsequently brings to bear upon it not s yet having been called into action.

To

To explain the origin of this instinct by the evolutionary sychology is, I believe, impossible in the present state of our nowledge; for there is no period in the history of the race at which it is conceivable that the latter should have derived any enefit from the birth and development of this peculiar passion. et I Lelieve it is now in some persons, were it permitted to assert tself, of even more intensity than is the highly beneficial inclina tion to which, as we have just seen, it is so strangely allied. refer to the striking similarity of this passion in man to that which is nanifested by monkeys, is not of course to explain its origin; ut I am quite sure it is in the monkeys that this explanation is to be sought. Everyone knows that these animals show the kcencst elight in torturing others simply for torturing sake, but every-ne does not know how much trouble an average monkey will ut himself to in order that he may gratify this taste. xample will suffice. A naturalist who had lived a long time in ndia told me that he has not unfrequently seen monkeys

One

feigning death for an hour or two at a time, for the express purpose of inducing crows, and other carnivorous birds, to approach within grasping distance; and when one of the latter were caught, the delighted monkey put it to all kinds of agonies, of which plucking alive seemed to be the favourite.

As I am not aware that any other animal exhibits this instinct of inflicting pain for its own sake-the case of the cat with a mouse belonging, I think, to another category-I believe, if its origin is ever to receive a scientific explanation, this will be found in something connected with monkey-life. PHYSICUS

Migration of Birds

YESTERDAY and to-day (17th and 18th inst.) continuous flights of migrant birds, chiefly fieldfares and redwings, have passed over this place in one uniform direction, from east to west, turning inland to the north-west, as though unwilling to cross Poole Harbour. The procession, so far as it attracted my own notice, began with daybreak of the 17th, and was so rapid and continuous all that day that enormous numbers altogether must have passed over us. Close flocks would come, and then a continuous flight of stragglers, but all in one and the same direction, and with little deviation from a well-defined aerial pathway, as though keeping some visible high-road. Yesterday the flight was down the wind; this morning against it; and although the flight was low and the birds seemed tired, none alighted in this neighbourhood. Whence did they come, and whither are they bound--east or west of this place? Can any of your readers say? H. C.

Bournemouth, Dec. 18

The Potato Disease

IN his letter of last week, Prof. Dyer states that his main object in his previous letter was "to claim for a distinguished English botanist credit for work done by him thirty years ago." In his previous letter this work is defined by Prof. Dyer to be the discovery by the Rev. M. J. Berkeley of the fact that the potato disease was due to the attacks of a parasitic fungus. As the service, with which botanists are familiar, that Mr. Berkeley has rendered in this matter, is the publication and advocacy in this country of the discovery previously made by Montague and others, with a few additional observations of his own, Prof. Dyer would confer a favour on his fellow-botanists by giving a more exact reference to the records which he is so anxious should be duly recognised. INQUIRER

HELMHOLTZ ON THE USE AND ABUSE OF THE DEDUCTIVE METHOD IN PHYSICAL SCIENCE*

SINCE

NCE the translation of the first part of this volume was published, its whole scientific tendency, and specially a series of individual passages in it, have been subjected to a more than vigorous criticism by Mr. J. C. F. Zöllner in his book "On the Nature of Comets." I do not think it necessary to answer expressions of feeling in reference to personal characteristics of the English authors or of myself. I have as a rule considered it necessary to reply to criticisms of scientific propositions and principles only when new facts were to be brought forward or misunderstandings to be cleared up, in the expectation that, when all data have been given, those familiar with the science will ultimately see how to form a judgment even without the discursive pleadings and sophistical arts of the contending parties. If the present treatise were intended only for fully educated men of science, Zöllner's attack might have been left unanswered. It is, however, essentially designed for students also, and as junior readers might perhaps be misled by the extreme assurance and the tone of moral indignation in which our critic thinks himself justified in expressing his opinions, I consider that it would be useful to answer the attacks made on the two English authors, so far as may * Translated by Prof. Crum Brown from Helmholtz's preface to the second part of the German edition of Thomson and Tait's "Natural Philoophy," vol. i.