place at which he does invoke the assistance of reversed selection is exactly the place at which reversed selection must necessarily have ceased to act. This place, as already explained, is where an obsolescent organ has become rudimentary, or, as above supposed, reduced to 5 per cent. of its original size; and the reason why he invokes the aid of reversed selection at this place is in order to save his doctrine of "the stability of germplasm." That the force of heredity should finally become exhausted if no longer maintained by the presence of selection, is what Darwin's theory of perishable gemmules would expect to be the case, while such a fact would be fatal to Weismann's theory of an imperishable germ-plasm. Therefore he seeks to explain the eventual failure of heredity (which is certainly a fact) by supposing that after the point at which the cessation of selection alone can no longer act (and which his first oversight has placed some 70 per cent. too low), the reversal of selection will begin to act directly against the force of heredity as regards the diminishing organ, until such direct action of reversed selection will have removed the organ altogether. Or, in his own words, "The complete disappearance of a rudimentary organ can only take place by the operation of natural selection; this principle will lead to its diminution, inasmuch as the disappearing structare takes the place and the nutriment of other useful and important organs." That is to say, the rudimentary organ finally disappears, not because the force of heredity is finally exhausted, tot because natural selection has begun to utilize this force against the continuance of the organ-always picking out those congenital variations of the organ which are of smallest size, and thus, by its now reversed action, reversing the force of heredity as regards the organ.

Now, the oversight here is that the smaller the disappearing structure becomes, the less hold must "this principle" of

reversed selection retain upon it. As above observed, during the earlier stages of reduction (or while co-operating with the Cessation of selection) the reversal of selection will be at its marimam of efficiency; but, as the process of diminution coninues, a point must eventually be reached at which the reversal of election can no longer act. Take the original mass of a now obsolescent organ in relation to that of the entire organism of which it then formed a part to be represented by the ratio 1:100. For the sake of argument we may assume that the mass of the organism has throughout remained constant, and that by "mass" in both cases is meant capacity for absorbing nutriment, ausing weight, occupying space, and so forth. Now, we may farther assume that when the mass of the organ stood to that of its organism in the ratio of 1: 100, natural selection was strongly reversed with respect to the organ. But when this ratio fell tot:1000, the activity of such reversal must have become esormously diminished, even if it still continued to exercise any influence at all. For we must remember, on the one hand, that The rever-al of selection can only act so long as the presence of a diminishing organ continues to be so injurious that variations in its size are matters of life and death in the struggle for existence; and, on the other hand, that natural selection in the case of the diminishing organ does not have reference to the presence and the absence of the organ, but only to such variations in its mass as any given generation may supply. Now, the process of reduction does not end even at I: 1000. It goes on to I: 10,000, and eventually 1: . Consequently, however great our faith in natural selection may be, a point must eventually come for all of as at which we can no longer believe that the reduction of an obsolescent organ is due to this cause. And I cannot doubt that if Prof. Weismann had sufficiently considered the matter, he would not have committed himself to the statement that **the complete disappearance of a rudimentary organ can only take place by the operation of natural selection."

According to my view of the matter, the complete disappear-❘ ance of a rudimentary organ can only take place by the cessation of natural selection, which permits the eventual exhaustion of heredity, when heredity is thus simply left to itself. During all The earlier stages of reduction, the cessation of positive selection was assisted in its work by the activity of negative or reversed election; but when the rudiment became too small for sach assistance any longer to be supplied, the rudiment persisted in hat greatly reduced condition until the force of heredity with regard to it was eventually worn out. This appears to me, as appeared to me in 1874, the only reasonable conclusion that can be drawn from the facts. And it is because this conclusion fatal to Prof. Weismann's doctrine of the permanent staBality of germ-plasm, while quite in accordance with all

P.S. Since the above article was sent in, Prof. Weismann has published in these columns (February 6) his reply to a criticism by Prof. Vines (October 24, 1889). In this reply he appears to have considerably modified his views on the theory of degeneration; for while in his essays he says (as in the pas sage above quoted) that "the complete disappearance of a rudimentary organ can only take place by the operation of natural selection"-i.e. only by the reversal of selection,-in his reply to Prof. Vines he says, "I believe that I have proved that organs no longer in use become rudimentary, and must finally disappear, solely by 'panmixia'; not through the direct action of disuse, but because natural selection no longer sustains their standard structure"-i.e. solely by the cessation of selection. Obviously, there is here a flat contradiction. If Prof. Weismann now believes that a rudimentary organ "must finally disappear solely" through the withdrawal of selection, he has abandoned his previous belief that "the complete disappearance of a rudimentary organ can only take place by the operation of selection." And this change of belief on his part is a matter of the highest importance to his system of theories as a whole, since it betokens a surrender of his doctrine of the "stability" of germplasm-or of the virtually everlasting persistence of the force of heredity, and the consequent necessity for a reversal of this force itself (by natural selection placing its premium on minus instead of on plus variations) in order that a rudimentary organ should finally disappear. In other words, it now seems he no longer believes that the force of heredity in one direction (that of sustaining a rudimentary organ) can only be abolished by the active influence of natural selection determining this force in the opposite direction (that of removing a rudimentary organ). It seems he now believes that the force of heredity, if merely left to itself by the withdrawal of natural selection altogether, will sooner or later become exhausted through the mere lapse of time. This, of course, is in all respects my own theory of the matter as originally published in these columns; but I do not see how it is to be reconciled with Prof. Weismann's doctrine of so high a degree of stability on the part of germ-plasm, that we must look to the Protozoa and the Protophyta for the original source of congenital variations as now exhibited by the Metazoa and Metaphyta. Nevertheless, and so far as the philosophy of degeneration is concerned, I shall be very glad if (as it now appears) Prof. Weismann's more recent contemplation has brought his principle of panmixia into exact coincidence with that of my cessation of selection.-G. J. R.

Newton in Perspective.

THE interesting modern science termed by the Germans Geometrie der Lage, and by the French and other Latin peoples géométrie de position, may be traced in germ to that part of Newton's "Principia" which deals with the construction of curves of the second order, and to what has survived in tradition of Pascal's lost manuscript entitled "Traité complet des Coniques." The more recent developments of this important subject cast much new light upon Newton's propositions, many of which we are now enabled to solve by easier and more direct methods. A noteworthy example is here fully worked out, in order to show how problems which Newton solved by indirect and circuitous processes may be solved more simply by the aid of modern graphics.

PROBLEM. -Given the four tangents EA, AB, BC', C'D (Fig. 1), as well as a point of contact; to construct the conic.-First it will be necessary to give some faint idea of Newton's solution of this problem, without entering upon details which can be found in the Latin edition of the "Principia" edited by Sir William Thomson and Prof. H. Blackburn. Having expounded at great length a general theorem for the transformation of curves, Newton transforms the quadrilateral figure formed by the four tangents into a parallelogram. Then he joins the given point of contact y, transformed according to the same principle as the given four tangents, to the centre O of the parallelogram

-which is also the centre of the conic-and producing the line O to y', so that Oy may be equal to Oy, he determines a second point of contact on the conic, by which means the problem is reduced to the case dealt with in the preceding proposition, showing how to construct the curve when three tangents and two points are given. Having in this way found five points on the transformed conic, Newton next proceeds to retransform the whole of the figure to its original shape, in order to apply his well-known method of constructing a conic of which five points are known.

Now all these transformations and retransformations of lines and quadrangles involve very tedious and laborious operations, which can be avoided by borrowing a few simple principles of modern geometry. The following two original solutions of the above problem will serve to illustrate this statement.

SOLUTION.-Case I. When the given point of contact a lies on one of the given four tangents.-Assume the given point of contact and the neighbouring apex B of the quadrangle as centres of projection, and the given tangent lines EA and C'D as punctuated lines. The meaning of the term "punctuated line," familiar to students of modern geometry, will appear in the sequel.

It will be seen that the fourth tangent AB cuts the first punctuated line EA in A and the second punctuated line C'D in A'. Now, according to a proposition of modern geometry, if the points A and A', in which the tangent AB intersects the two punctuated tangents EA and C'D, be projected by rays rA and BA' issuing from their respective centres of projection r and B, those rays will meet in a point A, situate on what is termed the perspective line of the pencils x and B.

Next imagine the tangent AB to revolve upon the curve so as gradually to approach the limiting position BC. In that (ase A will approach C, B will fall upon C', and the intersection of the projecting rays C and BC will coincide with C', which is therefore a second point on AC', the required perspective line of the pencils and B. Wherefore, in order to find a fifth or any number of tangents to the curve, choose any point E on the punctuated line EA, and project this point from, the corresponding centre of projection, upon the perspective line AC' in ; and then projecte from the second centre of projection B upon the corresponding punctuated line C'D in D. The line ED is a fifth tangent to the conic, and any number of tangents can be drawn in precisely the same way. Then, let F be any other point on EA. Join and produce F.x, intersecting the perspective line AC' in f; and from the centre B project upon the punctuated tangent C'D in F'. Then the line FF will be a sixth tangent to the conic.

COR, I. Since the lines AC', BD, and E all meet in the same point e, it follows that, in any pentagon ABC'DE circumscribed to a conic, the opposite diagonals AC and BI) and the line joining the fifth point F. to the opposite point of contact meet in the same point.

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Case II. When the given point of contact hes cutside of four tangents AEDCB.-By the corollary, Case I, if AB be the fifth tangent, it must pass through the given point of con tact in such a direction that the diagonals C'A and EB may intersect in a point I situate on a given line D.

Now let AB revolve about the fixed point of contact : as 1 fulcrum, whilst A and B describe the lines EC and CC' (Fig. 1 and 2). Then, necessarily, will be the centre of perspectivity of the punctuated lines EC and CC', whose centres of projection are respectively C' and E. But, by a well-known proposition of geometry of position, when the points of two converging puac tuated lines, such as EC and CC', are projected from opport centres in this fashion, the locus of the successive intersections of the rays C'A and EB, or in other words the variable posit of the point I, will describe a conic, which in the prese: instance is a hyperbola. But the problem is how to find the point I on the transversal L without constructing the hyperbol four points on which are already known. For it will be observed that, when A coincides with E, the point B will on the prolongation of Es, and the corresponding projecting rays E and C'E will meet in E, a point on the hyperbolz Similarly C' is a second point on the hyperbola. Again, as AR continues to revolve about the fixed centre of perspectivity, intersections A and B with the punctuated lines EC and C will ultimately coalesce in the point C, common to both those lines. Hence, since in that case the rays projecting the double point C from the centres E and C' meet in C, this point must lie on the hyperbola.

Fourthly, if the line C: be produced to intersect the line EC in N, it can be easily shown that i, the third point in the harmonic ratio GiN, is a fourth point on the hyperbola. A f point can be found by simply drawing AB in any direction traversing and intersecting EC in A' and CC' in B, and ther projecting A' and B' from the centres C' and E respectively by rays C'A' and EB' which will meet in a fifth point upon the hyperbola.

Thus, given these or in fact any five points EDITH (Fig 2

and dh'f respectively. Then, from any point S on the circumference of the circle, reproject the six points dht, d'h't', upon the same circumference in the points similarly lettered.

By means of this double projection from the centres E and i the Gints DHT have been transferred in duplicate from the hyperbola to the circle, or from one conic to another of a different species; and it is proved in treatises on modern geometry that points so transferred lose none of their projective properties. Hence the peints dht and d'h' on the circumference of the circle are allied projective systems. Therefore, in order to find the perspective ine common to both systems, choose one point of the first set as the centre of projection of the second system; and make t, the correlative point of the second set, the centre of projection of the system dht,

From project the points and h' by rays td' and th', and firm project the correlative points d and h by rays t'd and t'h. Then the correlative rays d' and 'd will intersect in a point do

n the required perspective line; and the correlative rays the and A will meet in ho, a second point on the same line. This espective line dh will intersect the circumference in two points and which, being joined to S and produced, will termine the double points I and g common to the hyperbola and transversal Ls. The complete quadrangle EC'IC shows that the harmonic ratios CiN and IL are segments of the same harmonic pencil P.

The lines E: and C'z are tangents to the curve at E and C' respectively; and z is the pole of the polar EC' with respect to the hyperbola. The proofs of these last two deductions may be fund in any good text-book on geometry of position. ROBERT H. GRAHAM.

Thought and Breathing.

PROF. MAX MULLER'S article on thought and breathing, in your issue of February 6 (p. 317) has just come into my hands. In it he states that the power of retaining the breath is practised largely by Hindus as a means towards a higher object, viz. the abstraction of the organs of the human body from their natural functions. The same custom prevails amongst a certain ect of Mahometans also-the so-called Softas.

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In 1878, when in the Central Provinces of India, I came 70s a native Christian-Softa Ali, as he was called--who had a history. His father had been a Cazi-or religious judge-and a wealthy man, who through scruples of conscience fell into disgrace with a certain native ruler, lost his all, and was banished. His son was, or became, a Softa, and after some years embraced Christianity from conviction, and at great cost to himself-for his wife and children would no longer consort with him. When describing to me the practices formerly enjoined upon him by religion, this man stated that a Softa is required to draw in and retain his breath and respire it again in various manners. He did not give full details as to how this should be effected, it said that the object of this procedure was to worship with every organ of one's body-heart, lungs, &c., in turn. He aded that this practice was a fruitful source of heart-disease. The following year, when staying at Futtehpore Sikri, near Agra, I saw and heard a Mahometan, unknown to himself, make evening devotions near the tomb of Suleem Chisti in the way above described; his movements, and the sounds he uttered, were most peculiar.

It has been often related, from well-attested evidence, that in the case of those who have been recovered from drowning, or of those who have been hung and cut down before life was extinct, a kind of automatic consciousness seems to be extraordinarily active in them at the time of their peril. It would appear that, a- regards Hindu and Mahometan devotees, and the drowning or partially hung man, a kind of asphyxia is the result, and that, when sensation is almost gone, the intelligence acquires increased activity. In our ordinary life, if our minds are intently fixed upon a subject, we instinctively and involuntarily

retain the breath.

When in Rajputana, and again when on the frontier of Chinese Tibet, I saw in each place a man who, to all appearance, seemed to have attained the power of perfect abstraction. In the former case, the villagers asserted that the devotee rose nly once a week from his most uncomfortable and constrained sition; in the second instance, the man-a most singular-lookng person-remained absolutely immovable the whole day. Both seemed to be in a kind of cataleptic trance.

HARRIET G. M. MURRAY-AYNSLEY.

Former Glacial Periods.

I HAVE long felt convinced that geologists are being misled in reference to former glacial epochs by failing to give due thought to a consideration referred to on former occasions, viz. that when the present surface of the globe has been disintegrated, washed into the sea, and transformed into rock, there will undoubtedly then be about as little evidence that there had been a glacial epoch during post-Tertiary times as there is at present that there was one during Miocene, Eocene, Permian, and other periods. JAMES CROLL.

Perth, March 6.

AUSTRALASIAN ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE.

THE

HE formation of this Association, mainly by the efforts of Prof. Liversidge, of Sydney University, and its first meeting in Sydney in August 1888, were noticed at the time in NATURE (vol. xxxviii. pp. 437, 623). One of the chief rules of the Association is that it shall meet in turn in the capital cities of the various colonies; and Melbourne was agreed upon as the second meeting-place. It was found inconvenient, however, to hold the Melbourne meeting during 1889, as should have happened in due course, for it is only after Christmas that all the Universities are simultaneously in vacation; and accordingly it was commenced on the 7th of January in the present year, and was continued through the following week. Some anxiety was felt as to the result of this choice of date, for there is always a risk in January of such continuous heat as would hinder the work and destroy the pleasure of the meeting; but the Association proved to be specially favoured in the matter of weather.

The following are the names of the officers of the Association and of the Sections. With regard to the latter, the rule obtains that Presidents are chosen from other colonies, while Vice-Presidents and Secretaries are chosen from the colony in which the meeting is held. President, Baron von Mueller, K.C.M.G., F.R.S. Local Treasurer, R. L. J. Ellery, C.M.G., F.R.S. General Secretaries: Prof. Archd. Liversidge, F.R.S., Permanent Hon. Secretary; Prof. W. Baldwin Spencer, Hon. Sec. for Victoria.

Assistant Secretary for Victoria, J. Steele Robertson. Sectional Officers :-Section A (Astronomy, Mathematics, Physics, and Mechanics)-President, Prof. Threlfall, Sydney University. Vice-President, Prof. Lyle, Melbourne University. Secretaries: W. Sutherland, E. F. J. Love.

Section B (Chemistry and Mineralogy)-President, Prof. Rennie, Adelaide University. Vice-President, C.

R. Blackett, Government Analyst, Melbourne. Secretary, Prof. Orme Masson, Melbourne University.

Section C (Geology and Palæontology-President, Prof. Hutton, Canterbury College, New Zealand. VicePresident, Prof. McCoy, C.M.G., F.R.S., Melbourne University. Secretary, James Sterling,

Section D (Biology)-President, Prof. A. P. Thomas, Auckland. Vice-Presidents: J. Bracebridge Wilson; P. H. MacGillivray. Secretaries: C. A. Topp, Arthur Dendy.

Section E (Geography)-President, W. H. Miskin, President of the Queensland Branch of the Royal Geographical Society of Australasia. Vice-Presidents: Commander Crawford Pasco, R.N.; A. C. Macdonald. Secretary, G. S. Griffiths.

Section F (Economic and Social Science and Statistics -President, R. M. Johnson, Registrar-General, Hobart. Vice-President, Prof. Elkington, Melbourne University. Secretaries: A. Sutherland, H. K. Rusden.

Section G (Anthropology)-President, Hon. J. Forrest, C.M.G., Commissioner for Crown Lands, Western

Australia. Vice-President, A. W. Howitt, Secretary for Mines, Melbourne. Secretary, Rev. Lorimer Fison. Section H (Sanitary Science and Hygiene)-President, Dr. J. Ashburton Thompson, Sydney. Vice-Presidents: A. P. Akehurst, President of the Central Board of Health, Melbourne; G. Gordon, Secretary, G. A. Syme.

Section I (Literature and Fine Arts)-President, Hon. J. W. Agnew, Hobart. Vice-Presidents: Prof. Tucker, Melbourne University (Literature Sub-Section); J. Hamilton Clarke (Music Sub-Section). Secretaries: Dr. Louis Henry (Music Sub-Section); Tennyson Smith (Literature Sub-Section).

Section J (Architecture and Engineering)-President, Prof. Warren, Sydney University. Vice-Presidents: A. Purchas, H. C. Mais. Secretary, A. O. Sachse.

All arrangements for the meeting were made by the Local Committee, of which Mr. R. L. J. Ellery, the Government Astronomer, was chairman, and Prof. W. Baldwin Spencer secretary. The greater share of the work devolved on Prof. Spencer, and to his indefatigable energy is mainly due the undoubted success of the meeting. The buildings and grounds of the University were placed at the service of the Association, and nothing could have been better than the accommodation thus afforded. A lecture theatre was set apart for each of the ten Sections; and, as these theatres are situated in different parts of the grounds, and some distance apart, they were all connected by telephone, so that the advent of each paper in any Section could be signalled in every other. The large Wilson Hall was used as a receptionroom; and a luncheon-hall, smoking-rooms, reading- and writing-rooms, a press-room, &c., were also provided, as also a special post- and telegraph-office. An official journal of the proceedings was published each morning, and every member was supplied with a copy of a special hand-book compiled for the occasion, and containing the following chapters:

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(1) "History of Victoria," by Alexander Sutherland. (2) "Geology of Melbourne," by G. S. Griffiths. (3) Aborigines of Victoria," by Lorimer Fison. (4) "Zoology, Vertebrata,” by Á. H. S. Lucas. (5) "Zoology, Invertebrata," by A. Dendy.

undoubtedly stands at the head of the scientific worker in Australia. He has been a colonist since 1848, and since 1852 has held the position of Government Botani in Victoria. His fame, which is based not only d immense amount of work he has done in his special subject, the botany of Australia, but on his early achieve ments as an explorer, may be indicated in the words use by Mr. Russell:-"In 1861 he was made a Fellow of the Royal Society; he received from Her Majesty the Quee the Knight Companionship of St. Michael and St. George was made a Commander of the Orders of St. Lago of Portugal, of Isabella of Spain, and of Philip of Hesse. was created hereditary Baron by the King of Wurten berg in 1871; and is honorary or corresponding member of a hundred and fifty learned societies." To this ene meration may be added what is, perhaps, the most honourable award of all-that of a Royal Medal by the Royal Society at the end of 1888. Throughout the colonies "the Baron" is known: a unique personality, not always wholly understood, but always recognized & a proud possession. His address, therefore, was listene to with peculiar interest, and perhaps all the more s that he did not confine himself to any special branch, but dealt generally with the past and future of Austral asian science.

The Presidents of Sections also, in many cases, chose for their addresses subjects of particular interest in Australia. Prof. Rennie spoke of the work that has been done in the investigation of the chemistry of native plants and minerals, and made suggestions as to how this work may in future be encouraged and facilitated. Prof Thomas discussed the problems here awaiting the bi logist, and the local desiderata in scientific education Mr. Miskin spoke principally of exploration in Australia and New Guinea, and of the importance to the colonies of Antarctic exploration; but he also discussed the chief geographical work now being done in other parts of the world. Mr. Forrest's address dealt with the present con dition of the Australian aboriginal races. Dr. Ashburton Thompson discussed the sanitary organizations of Victora and New South Wales, and the modes of obtaining and interpreting health statistics. Prof. Warren spoke of the

(7) Botany," by C. A. Topp.

(8) Commerce and Manufactures," by W. H. Thodey. (9) "Climate," by R. L. J. Ellery, C.M.G., F.R.S., Government Astronomer.

Over six hundred members, representing all parts of Australasia, were in actual attendance, the total membership roll numbering more than a thousand. Some hundred and fifty papers in all were set down for reading in the various Sections. All these figures show a large increase since the first meeting, and give gratifying evidence of the growing interest taken in science throughout the colonies; further proofs of which are to be found in the facts that the Government of Victoria voted the liberal sum of £1000 towards defraying the expenses of the meeting, and that the entertainments provided by the hospitality of prominent citizens were numerous and on a most sumptuous scale. Many visits to places of scientific interest were also arranged for-short afternoon excursions for those who might not care for continuous Sectional work, and longer excursions at the conclusion of the meeting, under special leaders, to the Australian Alps, the Black Spur and Marysville, Gippsland Lakes, Ferntree Gully, Ballarat, and Sandhurst, all of which proved highly successful.

At the opening meeting in the Town Hall-presided over by His Excellency the Governor, the Earl of Hopetoun -the President, Baron Sir Ferdinand von Mueller, delivered his address, after being introduced by his predecessor in office, Mr. Russell, the Government Astronomer of New South Wales. Baron von Mueller

conditions and requirements. Dr. Agnew reviewed the literature and art of Australia. In the other Sections the Presidents chose subjects that do not owe their interest to local colour. Prof. Threlfall gave an account of the present state of electrical knowledge; Prof. Hutton's address was on the oscillations of the earth's surface. and Mr. Johnston spoke generally of current social and economic problems. A large proportion of the papers read by members in the various Sections were als Australian in their character. This was specially the case in the Sections of Geology and Anthropology; where. perhaps, the most valuable original work was commun cated. As the Transactions will soon be published, the individual papers need not now be noticed; but reference may be made to the work done in the form of reports from Committees appointed at the previous meeting The most bulky and perhaps the most valuable of these reports is that by a Committee which undertook, with Prof. Liversidge as its secretary, to prepare a census of the known minerals of the Australasian colonies. It disposes of New South Wales (only such information being given as was required to supplement Prof Liversidge's published work), Queensland, and New Zealand. The portions dealing with Victoria and Tasmania are in process of completion; and, the Committee having been re-appointed, it is hoped that by next year the whole census will be complete. The publication will probably be delayed till then, and it will if possible take the form of a separate volume. A very important recommendation was made by another Com mittee (Prof. Haswell, of Sydney, secretary), which when

it is carried out will do much for biological research, viz. that steps be taken to establish and endow a central biological station at Port Jackson. Among the other reports may be mentioned one on the Polynesian races and Polynesian bibliography.

At the final meeting of the General Committee of the Association new special Committees were appointed to investigate and report on the following subjects: wheat rust, the manner of laying out towns, the preparation of geological maps, the arrangement of museums, the fertilization of the fig, Australian tides, and the present state of knowledge with regard to Australasian palæontology. A Committee was also appointed to formulate a scheme for obtaining practical assistance from the various Colonial Governments in the collection of material for research-chemical, geological, or biological. Other pecial Committees were appointed for the publication of the Transactions and for the revision of the laws of the Association.

The next meeting is to be held in Christchurch, New Zealand, probably in January 1891 ; and Sir James Hector has been elected President, and Prof. Hutton, Secretary. It has also been decided to hold the fourth meeting in Hobart, Tasmania, so that the Association will not again meet on the mainland for three years. To adventure so far as Christchurch is somewhat bold in so young an Association; but the success of the Melbourne meeting has demonstrated its usefulness and popularity, and warrants the belief that many will cross the water next year. There is even a strong hope felt by some that the occasion and the place may tempt a few of the members of the parent British Association to make the longer voyage from home, and see for themselves what is being done and what waits to be done for science at the antipodes. ORME MASSON.

METEOROLOGICAL REPORT OF THE "CHALLENGER" EXPEDITIONA PREVIOUS to 1872, discussions of the fundamental problems of meteorology relating to diurnal changes in atmospheric pressure, temperature, humidity, wind, and other phenomena, may be regarded as restricted to observations made on land. It had then, however, become evident that data from observations made on land only, which occupies about a fourth part of the earth's surface, were quite inadequate to a right conception and explanation of meteorological phenomena; and hence, when the Challenger Expedition was fitted out, arrangements were made for taking, during the cruise, hourly or two-hourly observations. These observations were published in detail in the "Narrative of the Cruise," Vol. II. PP. 305-74, and are still by far the most complete yet made on the meteorology of the ocean.

Elaborate observations were likewise made on deepsea temperatures, which were at once recognized as leading to results of the first importance in terrestrial physics, and opening for discussion the broad question of oceanic circulation, on a sound basis of authentic facts. Preliminary, however, to any such inquiry, a full discussion of atmospheric phenomena was essential, requiring for its proper handling maps showing the mean temperature, mean pressure, and prevailing winds of the globe for each month of the year, with tables giving the data from which the maps are constructed. In other words, what was required was an exhaustive revision and ratification of Dove's isothermals, 1852; Buchan's isobars and prevailing winds, 1869; and Coffin's winds of he globe, 1875.

Report of the Scientific Results of the Voyage of H.M.S. Challenger fining the Years 1875-76." Prepared under the superintendence of John Morray, LL.D "Physics and Chemistry," Vol. II., Part V. "Report on Atspheric Circulation. By Alexander Buchan, M. A., LL.D.

The work was entrusted to Mr. Buchan, of the Scottish Meteorological Society, in 1883, and was published in the beginning of this year. In addition to the tables of the appendices, giving the results of the Challenger observations, the more important are those giving the mean diurnal variation of atmospheric pressure at 147 stations in all parts of the world; the mean monthly and annual pressure at 1366 stations; a similar table of temperatures at 1620 stations; and the mean monthly and annual direction of the wind at 746 stations. It is believed that these tables include all the information at present existing that is required in the discussion of the broad questions raised in the Report, which includes, with the exception of the rainfall, all the important elements of the climates of the globe.

The Report itself is divided into two parts, the first dealing with diurnal, and the second with monthly, annual, and recurring phenomena. This is the first attempt yet made to deal with the diurnal phenomena of meteorology over the ocean-the temperature, pressure, and movements of the atmosphere, together with such phenomena as squalls, precipitation, lightning, and thunderstorms.

In equatorial and subtropical regions, the mean temperature of the surface of the sea falls to the daily minimum from 4 to 6 a.m., and rises to the maximum from 2 to 4 p.m., the amount of the diurnal variation being only o°9 F. In the higher latitudes of the Antarctic Ocean, the diurnal variation was only o°2. Of the four great oceans, the greatest variation was 10 in the North Pacific, and the least o°8 in the Atlantic. This small daily variation of the temperature of the surface of the sea, shown by the Challenger observations, is an important contribution to physical science, being in fact one of the prime factors in meteorology, particularly in its bearings on the daily variations of atmospheric pressure and winds. The diurnal phases of the temperature of the air over the open sea occur at the same times as those of the temperature of the surface, but the amount of the variation is about 3°0, and when near land the amount rises to 4°4. The greater variation of the temperature of the air, as compared with that of the surface of the sea on which it rests, is a point of much interest from the important bearings of the subject on the relations of the air, and its aqueous vapour in its gaseous, liquid, and solid states, and the particles of dust everywhere present, to solar and terrestrial radiation. Thus the air rises daily to a higher and falls to a lower temperature than does the surface of the sea on

which it rests.

The diurnal variation in the elastic force of vapour in the air is seen in its amplest form over the open sea, the results giving a curve closely coincident with the diurnal instead of rising towards, and to, the daily maximum at curve of temperature. But near land, the elastic force these hours, and indicates no longer merely a single, but noon and 2 p.m., shows a well-marked depression at a double maxima and minima. In other words, the curve now assumes the characteristics of this vapour curve as observed at all land stations, or where during the warmest hours of the day ascending currents rise from the earth's surface, and down-currents of drier air take their place. An important point specially to be noted here is that over the open sea, hygrometric observations disprove the existence of any ascending current from the surface of the sea during the hours when temperature is highest. On the other hand, the curve of relative humidity is simply inverse to that of the temperature, falling to the minimum at 2 p.m. and rising to the maximum early in

the morning.

As regards the diurnal variation of the barometer, it is shown that the special forms of the monthly curves are, in their relations to the sun, direct and not cumulative as is the case with most of the monthly mean results of