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arranged, they conspire to establish a virtual second joint, at right angles to the topmost joint, and at some point below it not necessarily coinciding with the position of any one of the actual joints, and apparently varying for different positions of the plane of vibration.

At this stage I showed some of my pendulum's tracery to my brother-in-law, Mr. E. J. Routh, M.A., of St. Peter's College, Cambridge, and received some hints from him which led me to adopt an arrangement whereby the position of the lower joint could be varied, so as to bring the two periods of vibration into any simple proportion, as 1:2, 2:3, &c. This was done by a very simple mode of suspension,-two cords hanging from two fixed points some distance apart, and passing through a small ring that could slide up and down the concurrent cords and be fixed at any height. In this arrangement I found the germs of an infinite variety of curious and elegant curves, that gave a new lease of life to my course of experiment. Before attempting anything, I drew in my pocket-book the skeletons of the curves that would be described corresponding to the proportions, I:2, 2:3, 3:4, 4:5, 5:6, 6:7, 78, 8:9, in the periods of quick and slow vibration. Then I hung a bullet by two threads from two points about ten inches apart on the circumference of a child's wooden hoop, fixing the hoop upright with the bullet swinging inside the circle. Another bit of thread furnished the sliding-ring to nip the two convergent threads at any desired point, and a few trials enabled me to fix it pretty accurately for the proportion : 2, so that the bullet would swing in the plane of the hoop in half the time it took to swing at right angles to the plane of the hoop, making two vibrations in the plane of the hoop to one vibration athwart. (The length of the pendulum varies as the square of the period of vibration, so the slider was at a point one quarter of the distance from the bullet to the horizontal line between the two points of suspension.) It was with great interest that I watched the motion of my pensile bullet, and greeted the verification of my pocket book sketch. Pull the bullet aside and start it obliquely, and it describes a crescent-moon, the two horns being formed by the double swing in the plane of the hoop, while the length of the crescent measured from tip to tip is given by a single swing athwart the plane of the hoop. Start the bullet from rest at the centre by a sudden blow obliquely given, and it describes a figure of eight with its length athwart the plane of the hoop. (See Figs. 5 and 6.) Other proportions gave still more curious results in accordance with my skeleton sketches, and made me impatient to try them on a larger scale. The lead at my command I packed into a long-shaped zinc box, with a tubular orifice at the top, which in my service became the bottom. To the lead I added a stone jar containing some 10 lbs. of mercury, and made everything secure with cordage. The dependent tubular orifice seemed made on purpose to accommodate a few inches of wooden roller which carried the glass pen, and a diagonal beam in the ceiling of my bedroom offered a capital fixture for two rings about four feet apart, giving suspension to two iron chains by which my incongruous pendulum-bob was doomed to swing. To nip the chains together at the requisite height, I used a loose link which hooked into the corresponding links in the two convergents, and made a very rude and coarse adjustment, which left all accuracy to chance. It chanced, however, that the adjustment for the proportion 2:3 was beautifully accurate, and I shall never forget the feeling of delight which I experienced while watching the marvellous fidelity with which the pen point traced the curve appropriate to that proportion. The pendulum was drawn aside and started obliquely on one side of the plane of slow vibration, and having to make three vibrations across that plane to two vibrations to and fro, it compounds these into a curve like a capital Q with two tails, one on each side, looking like a swallow-tailed balloon. (See Fig. 9.)

At the end of the second to-and-fro vibration the pen returns to the point whence it started, except that friction compels it to fall short little by little at every stroke; but if the adjustment is accurate, as it was in this particular case, the shape of the curve remains the same from first to last, and the figure is filled up to the very centre by the orderly description of curve within curve conspiring to produce a web of lines of astonishing regularity. If the adjustment of the connecting link is very slightly inaccurate, the curve begins to change its shape little by little at every stroke, in one way or another, according as the link is too high or too low; and wonderfully intricate is the result, for after a due series of intermediate stages, the original figure reappears, but reversed; and after anol er series of changes it presents itself again to view in its original posture, but much diminished by the friction that he s been in operation throughout all these changeful phases. It may be imagined how intricate the web becomes, though the limits of illustration do not allow me to give a specimen here. It was easy to eliminate all the transition-curves from the tracery, by depressing the paper for the proper interval, and allowing it to return to contact with the pen only at those distinctive phases when the original figure was reproduced either erect or reversed. I obtained a very curious specimen by applying this selective method to the case of the proportion 1:2, allowing the pen to mark only the crescents and the figures of 8 in alternate series, converging orderly to the centre. For the suspension of the paper, I fixed four pairs of upright rods at the four corners of a shallow tray, which could be slipped under the pendulum, and each rod gave support to an india-rubber band, which, with its fellow at right angles, was attached by a small hook to the coresponding angle of the paper. Each bind could be slid up or down its rod, to allow of nice adjustment of the level of the paper, and the whole tray could be raised on a footstool or chair, to suit the elevation of the pendu un when the slider was run aloft in attaining the proportions nearer unity, such as 7: 8, or 8 : 9.

The iron chain was soon exchanged for strong cords, passing through a narrow wire ring, which could be arrested at any point by a needle driven through both cords below the ring. This was a small improvement, allowing more accuracy in the adjustment of the slider, and therefore more accuracy in the proportion between the two periods of quick and slow vibration. But it was still very far from satisfactory. Meanwhile I had ordered a cylinder of lead, weighing half a cwt, to be cast, with a hole through the axis; for my zinc box full of "notions" was so tall that I could not bring the slider near enough to the centre of gravity to obtain any proportion lower than 1 : 3, and that only with great trouble. When the cylinder of lead appeared, I sawed it into two unequal portions, so that I could use either or both; and instead of simple cords, which twisted in a most troublesome manner below the sliding ring introduced a stiff rod of fir to carry the lead by a cross pin, and I used two pairs of cords passing through holes in a slider on either side of the central rod. This slider was a small block of wood pierced to fit the rod, and provided with a lateral screw to fix it at any required height. This arrangement ensured admirable steadiness and freedom from torsion, and a great many sheets were filled with the improved performances of the machine; but there still reinained an important defect to remedy. The coarse cords, at the point where they entered the holes in the slider, made a very rough hinge for the cross vibration to rely upon, and it was manifest in the tell-tale records of the curves described that considerable change of period took place between the beginning and the end of the web; and the change was always such as to increase the disparity between the two periods, which could only mean that the level of the centre of quick vibration in the cords immediately above the slider was lowered when the range

of oscillation diminished. It was easy to see that a large oscillation would strain the cords to a greater height above the slider than would be called for in a smaller oscillation. The truth of this surmise was proved by the success of the remedy applied. Instead of cords I used two pairs of broad tapes, and instead of a solid slider I made one in two halves, embracing the rod in the centre and nipping the concurrent tapes on either side between their opposed faces, being clamped together by thumb-screws beyond the tapes on either side. Here the slider had no firm hold on the rod beyond the accuracy of its fit, which served to prevent torsion, but had firm hold on the pairs of tapes, pinching them with especial accuracy at the upper edge of the slit in which they lay between the two halves, and reducing the hinge there to a narrow line no thicker than the pairs of tapes instead of the gross thickness of the cords which they superseded. The improvement of the pendulum's performance on paper was very striking. When well adjusted, it was scarcely possible from beginning to end to detect any change in the shape of the figure described; scarcely possible, I say, for even now our hinge is not a mathematical line, and we do not obtain perfect mathematical accuracy in our results. Further improvement might be obtained by refinement in tapes and slider, or by increasing the total height of the pendulum, or by substituting some other form of hinge; but the form which I have described is so simple, and its performance so good, that I am content to accept its one very small fault for the sake of its many excellent qualities.

Figures 1-12 are the produce of this pendulum thus improved. They are only a few of the most interesting out of an endless variety of interesting curves, and are chosen as characteristic specimens of a series too extensive to be fairly represented except by a much larger number of illustrations. Figures 1 and 2 represent the proportion 1: 3, the lowest that is easily attainable without a loftier pendulum; and the following pairs of figures show successively the proportions 2:5, 1:2, 3:5, 2:3, 3: 4. Each of these is illustrated by two figures exhibiting the two chief types of the curve proper to that proportion. They may be termed the cusped type and the looped type. It will be seen that the two cusps in the first figure of each pair are opened into loops in the second, and that each loop in the first is doubled in the second. Between these two typical forms we have an infinite series of intermediate forms possessing features of great interest, those nearest the cusped type especially being characterised by a peculiar "watered" appearance, due to the intersection of two sets of lines very slightly inclined to one another. This is seen, for example, in Fig. 3, which errs a little from the perfect type.

Accuracy of proportion between the two periods of vibration could only be arrived at by repeated trials. The sliding-clamp sufficed for coarse adjustment, but for fine adjustment it was found necessary to attach a subsidiary weight below the large one in some way admitting of considerable range of position, so as to alter minutely the position of the centre of gravity. A heavy iron nut travelling easily on a screw-thread cut on the depending shaft that carried the pen supplied this want, and greatly facilitated the attainment of the utmost accuracy at command.

With a pendulum only seven or eight feet high, there is great difficulty in obtaining the curves that correspond to any proportions lower than 1 : 3, because the slider cannot be brought within a certain distance of the centre of gravity, which lies somewhere in the middle of the lead. To obtain the proportion 1: 3, that is, to make the pendulum swing three times across for every one swing to and fro, we must lower the slider within a foot of the centre of gravity (the length of the pendulum varying as the square of the period of oscillation), and to obtain the proportion : 4, the distance between the

slider and the centre of gravity must be 1-16th of the height of the pendulum, or only six inches in the present instance; but three or four of those six inches are taken up with the thickness of the lead and the attachments of the tapes, and the rest with the depth of the slider, and so the curve cannot be obtained without a more lofty suspension for the pendulum. This greater elevation I found in the great octagonal room which Sir Christopher Wren built as the chief room of the Royal Observatory in Greenwich Park. By means of two hooks fixed above opposite windows in this room, from which my tapes converged to the middle, I got a height of eighteen feet, and was able to reach such proportions as I : 4, 15, 1:6. At this extreme it was really amusing to watch the busy haste of the manifold crossvibration over-riding the staid gravity that marked the slower oscillation to and fro. To obtain proportions lower yet than these, I should want a great increase in height of suspension; but there is no great inducement to attempt this, as the nature of the curve may be foreseen at a glance, and is marked by extreme simplicity-merely a zigzag or a string of beads.

Some of these experiments with lofty suspension were made on stormy days; and while watching the travels of the delicate pen-point, I could see that their regularity was slightly disturbed by every gust of unusual violence that beat against the high walls.

But this article would never end if I allowed myself to dwell on all the points that called for attention in the course of experiment which I have been describing. I fear I have exceeded due limits already, and feel that I owe an apology to the reader for so large a trespass on his patience. My apology must be the elegance and exquisite symmetry of these natural curves in their admirable obedience to a purely natural law, and the great pleasure I have enjoyed the sense of high privilege I have felt-in their investigation. I understand that these curves, or some of them, have been demonstrated before, by means of a stream of sand flowing from a hole in the base of a vessel that was used as the weight of the pendulum, and I believe that steel springs of elliptic or oblong crosssection have been made to trace such curves as that which first attracted my attention in the vibration of my slender acacia-twig; but I am not aware that any specimens of the series have ever before been exhibited in a form that rendered them accessible to the public eye.

HUBERT AIRY

SOME SPECULATIONS ON THE AURORA

IN

N preparing a lecture on the Aurora Borealis some months ago, I was led to some speculations which may or may not be new, and may or may not be of some value. I will submit them to the readers of NATURE.

*

I assume of course that the auroral rays extend to great heights above the surface of the earth, that they are sensibly parallel, and that their apparent point of convergence is, generally speaking, that to which the freelysuspended magnet points. In the great aurora of October 24, 1870, this point was close to n Pegasi at 8.30 P.M., coinciding very well with the direction of the magnet. Remembering that this aurora was witnessed over a large part of the northern hemisphere, and that there was a contemporaneous aurora in the southern hemisphere, and, assuming that at each place the direction of the auroral streamers is approximately parallel to the magnet, we must conceive the earth, during such an auroral display, as a globe with streamers of light radiating and diverging from its polar regions, and spreading far out into space. The general direction of these streamers at different spots on the earth will be got by placing a magnet below a sheet of paper and getting the magnetic curves with iron filings, *To-night it is a few degrees below a Cygni (but not clearly defined) at

11 P.M.

and then describing a circle, to represent a section through the axis of the earth so that the magnet shall occupy the central part, about two-thirds of its diameter. The portion of the magnetic curves outside the circle will cut the circle at different angles, and fairly represent the directions of the auroral streamers.

Now, Arago, in his catalogue of auroras, shows that during the months of September, October, March, and April we are especially favoured with auroras; and that in these months they are both brighter and more frequent than at other times. This periodicity indicates an extra terrestrial origin for auroras. Does it not show that during those months we pass through an auroral region, just as in November and August we pass through meteoric regions, or, in other words, that we intersect a ring of some substance capable of being electrified by the earth in its passage, when there is any change in its magnetic power, and so rendered luminous? But it is impossible not to conjecture that this ring or disc is the very disc which is visible to us as the zodiacal light; for besides the fact of zodiacal light being specially visible during the same months, there is the positive evidence of spectrum analysis to the identity of the substances luminous in the aurora and the zodiacal light. We are led then to the hypothesis that there exists round the sun, and extending as far as our carth, an atmosphere, consisting of an unknown element, a gas of extreme lightness, and that this atmosphere is especially condensed in the form of a disc extending round the sun, but probably not concentric with it. The same element appears to exist in the solar corona, and was also detected in the vague phosphorescent luminosities of the sky on a particular evening, by, I think, Angström.

I wish to suggest, therefore, that catalogues of auroras may, like catalogues of meteors, determine auroral regions in the earth's orbit, and that two such regions are, in fact, already shown by Arago's catalogue, and that this periodicity, as well as the results of spectrum analysis, indicate a cosmical origin for auroras.

There is one more point which may be interesting. The luminous streamers have a lateral motion; they shitt sideways, and in fact rotate round their pole. Is this motion of rotation always, or even generally, in the same direction? I have not observed it often enough to speak with confidence. But if so, it must have some definite cause, and will be analogous to that of rotation in a definite direction of an electrical current round the pole of a magnet. The earth must be looked upon as a delicate solar electroscope and magnetometer, and the electrical discharge round the earth is stratified, and is in lines and strata that have, perhaps, motions in definite directions.

It may be worth remarking that the 22nd, 23rd, 24th, and 25th of October are the most famous days in the year for auroras, at least in the present century, and that the greatest displays of all on those days have happened at intervals of multiples of eleven years. Last year we had splendid auroras on the 24th and 25th; there is, therefore, some ground for expecting fine auroras on the same nights this year, if the auroral cycle corresponds to the sunspot and magnetic cycles. J. M. WILSON

NOTES

We learn from Indianapolis journals, received at the moment of going to press, that the American Association for the Advancement of Science commenced its sittings on the evening of August 21 by an opening address from the retiring president, Prof. T. Sterry Hunt, on the Iron Interests of Indiana, in which he com pletely sustained every claim that had been made for the State, showing conclusively that it has the elements within its borders from which to secure a manufacturing future that shall make Indiana the mediterranean workshop for the whole country. The sections commenced their sittings on the following day, and San Francisco was fixed on as the next place of meeting. An extra

double number of the American Naturalist for September 15 will give a full report of both the opening address and the sectional proceedings. In a future number we shall give an epitome of all matters of interest discussed at the meeting.

M. JANSSEN has been commissioned by the French Govern ment to proceed to the East to observe the total Solar Eclipse of December next. He has, therefore, been compelled to decline the offer made to him by the British Association to take part in the British Expedition.

THE President of the Royal Society has received a telegram from the Government Astronomer, Melbourne, that the Eclipse Expedition will leave that port on November 20.

WE regret that owing to the omission of a sentence, the note respecting the distinguished visitors at Section A of the late meeting of the British Association, read incorrectly in a small proportion of the edition of our last number. We now supply the omission by giving the following probably unexampled list of Senior and Second Wranglers and Smiths' Prizemen who were present :-Adams, Cayley, Challis, Stokes, Hon. J. W. Strutt, Hopkinson, Kelland, Tait, Wilson, Thomson, Maxwell, Sylvester, Clifford, Jack, J. W. L. Glaisher; of these the first nine were Senior Wranglers.

WE learn from the British Medical Journal that in accordance with the will of the late Dr. Lacaze a prize of 10,000fr. is to be awarded by the Faculty of Medicine of Paris every second year to the best work on phthisis and on typhoid fever alternately. The first prize will be awarded at the end of the academical year 1871-2, for the best work on phthisis. Essays (with a distinguishing motto and the author's name in a sealed envelope) must be sent in before July 1, 1872. The prize is open to foreigners.

IN a paper read before the Natural History Society of Boston (U.S.), Mr. W. T. Brigham gives an account of several remark. able earthquakes that have occurred in New England, with a list of all such phenomena that have occurred in that region from 1638 to 1870. Some of these disturbances appear to have been violent and protracted.

IO.

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WE understand from the Geological Magazine that there will shortly be published a Geological Atlas of England, by Mr. W. Stephen Mitchell. The Atlas will contain the following Maps 1. Cambrian (of Survey); Lower Cambrian (of Sedgwick). 2. Lower Silurian (of Survey); Middle and Upper Cambrian (of Sedgwick). 3. Upper Silurian (of Survey); Silurian (of Sedgwick). 4. Old Red Sandstone; Devonian. 5. Carboniferous Limestone; Yoredale Beds. 6. Millstone Grit; Coal Measures. 7. Permian (of Survey); Pontefract Group (of Sedgwick). 8. New Red Sandstone; Rhætic (Penarth). 9. Lias. Lower Oolite. II. Middle Oolite. 12. Upper Oolite. 13. Wealden; Neocomian. 14. Gault; Upper Greensand ; Chalk and Chalk Marl. 15. Eocene. 16. Crag. 17. Alluvium. 18. Bone Caves. 19. Metamorphic (?) 20. Igneous. The Maps will be printed in colours, each Map exhibiting only the range of one formation, and the names of places on the formation. In some few cases, where it is requisite, as a clue to the locality, to introduce the names of places near, but not on, the formation, these will be printed in a different type. The Maps (11 in. by 9 in.) are based on a photographic reduction of the last edition of the Greenough Map, which is published under the direction of a committee appointed by the Geological Society. In all cases where, through researches more recent than this last edition, any changes have been adopted in the grouping of the beds, this atlas conforms with the latest alterations. The revision of the proofs of particular maps has been kindly promised by Mr. W. Boyd Dawkins, F. R.S., Mr. W. Whitaker, Mr. H. Bauerman, Mr. J. W. Judd, Mr. Charles Moore, Mr. W. T. Aveline, and others. Letter-press will accompany each map, giving in a tabulated form the subdivisions of the formations, the

origin of the names of the groups of beds, their lithological characters, thickness, range, &c., with a historical notice of the various classifications that have been at different times employed. The lists of fossils will be arranged on a new plan, showing in a tabulated form for each formation the genera that first appear, those that last appear, and those that are numerically abundant in that formation. Separate tables give the characteristic species. These lists are prepared expressly for this work by Mr. R. Etheridge, F.R.S., &c., Paleontologist to Her Majesty's Geological Survey of Great Britain.

THE Continental scientific journals record the death of Dr. Milde, a well-known botanist, whose contributions to systematic cryptogamic botany are especially valuable.

We have to notice the death, at a very advanced age, of James De Carle Sowerby, the first secretary of the Royal Botanic

Gardens, Regent's Park, an office which he held till last year, when he resigned it in favour of his son. Mr. Sowerby belonged to a family, many members of which have distinguished themselves by their devotion to various branches of science, and to the pictorial illustration of natural objects.

THE Essex Institute publishes an obituary notice of its late president, Mr. Francis Peabody, of Salem, who died October 31, 1867, and who was noted for his researches in mechanical physics.

THE trustees of the Manchester Grammar School are so satisfied with the excellent work done in the Physical Science Department, under the superintendence of Dr. W. M. Watts, that they have begun to fit up a second and larger laboratory, at the cost of from 700l. or 800l. It is only three or four years since this department of the school was opened, and already many valuable scholarships and other honours have been gained by the boys.

THE following eminent archeologists are announced as contributing papers for the next session of the Society of Biblical Archæology :-M. Heinrich Brugsch, F. C. Chabas, Clermont Ganneau, and the Chevalier de Sauley. The first part of the society's transactions will be ready early in the spring, and will contain articles by Dr. Birch, J. W. Bosanquet, M. Ganneau, Prof. Lowne, Lieut. Prideaux, G. Smith, and H. Fox Talbot. THE Society of Arts have consented to give their co-operation to the Polytechnic Exhibition, to be held at Moscow next year, in celebration of the two hundredth anniversary of the birth of Czar Peter the Great.

ACCORDING to recently-published statistics of the University of Edinburgh Botanical Class, in the session of 1871 the number of pupils was 306. Of these, 241 (including 5 ladies) were medical students, 12 pharmaceutical students, and 53 general students.

THE Archæological Society, whose gathering at Weymouth we recorded last week, devoted Wednesday to an examination of objects of antiquarian interest in that town, including the Corporation regalia and muniments. On Thursday papers were read as follows:-By Mr. H. S. Cuming, F.S.A., "On the Patron Saint of Dorset, St. Edward, King and Martyr." By Mr. J. Drew, F. R.A.S., F.G.S., "On Art Treasures and their preservation." By Mr. G. Eliot, "On the Antiquities of Portland." There was afterwards an excursion to Corfe and Dorchester, visiting several objects of interest on the way. The papers read on Saturday and Friday evenings were as follow Mr. J. R. Planché, Somerset Herald, "On the Family of Robert Fitzgerald, the Domesday Tenant of Corfe." Mr. Edward Levien, M.A., F.S. A., Hon. Sec., "On Wareham and its Religious Houses." Mr. W. H. Black, F.S.A., "On Wareham

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and the Earliest Historic Monuments in Dorset." Rev. William Barnes, B.D., " On the origin of the name and people of Dorset."

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Mr. Joseph Stevens, M.D., "On newly-discovered Roman and Saxon remains at Finkley near Andover." The meeting was brought to a close on Saturday evening. Saturday's excursion was first by rail to Bindon Abbey, thence to Wareham, and afterwards by rail to Corfe Castle. The concluding meeting was held at the Royal Hotel on the return of the excursionists to Weymouth, at 8.30, when, after the reading of some papers, the usual formal resolutions and votes of thanks to the gentlemen who had assisted the Association in conducting the proceedings were passed and the congress was brought to a close.

THE Annual Meeting of the Devonshire Association for the Promotion of Literature, Science, and Art, recently held

its

sittings at the picturesque little town of Bideford, occupying three days, the retiring President, Mr. J. A. Froude, resigning the chair to the Rev. Canon Kingsley, who gave an

eloquent and interesting address. Papers were read, mostly of an archæological and geographical character, by Mr. Pengelly, Mr. Spence Bate, and other distinguished Devonians.

Ir is stated that Prof. Watson, of the University of Michigan, has discovered a new planet in the constellation Capricorn, of the tenth magnitude. This is the 115th of the series.

MR. J. R. HIND, F.R.S., has calculated the Ephemeris for Greenwich mean time of Futtle's Comet, which will be visible during this and next month. According to Prof. Luther, its next perihelion passage will occur about the 30th of November. The following are Mr. Hind's figures:

Right Ascension. 100° 13'2'

Declination.

1871 Sept. I

62° 22°7'

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PROF. A. HALL sends us some careful Equatorial Observations made at the U.S. Naval Observatory, Washington, and Supplementary Notes on the observations for magnetism and position made in the U.S. Naval Observatory expedition to Siberia to observe the Solar Eclipse of August 7, 1869.

A RECENT number of the "Astronomische Nachrichten contains an elaborate paper by Prof. E. Schönfeld, "On the Change of Light of Variable Stars."

THE Journal of the Society of Arts states that a memorial monument has been erected in New South Wales to the memory of Captain Cook, at the supposed place at which he landed from the Endeavour in April, 1770. On the monument are two brass plates, one bearing the following inscription :-"Captain Cook landed here 28th April, 1770. Victoria Regina. This monument was erected by the Hon. Thomas Holt, M. L. C., A. D. 1870. The Earl of Belmore, Governor." The other contains the following words from Captain Cook's journal :-" We discovered a bay and anchored under the south shore, about two miles within the entrance, in 6 fathom water, the south point bearing S. E., and he north point east. Latitude 34° S., longitude, 208 37°." The entrance to the bay where Cook landed has other memorials. On the north side is the column erected, on behalf of the French nation, to the French navigator, La Perouse. The enclosure around the column is planted with trees and flowers. The monument erected by Mr. Holt is on a place less elevated, but it can, nevertheless, be seen from several parts of distant suburbs. Public subscriptions are being made for a monument of a more costly kind, to be erected in one of the parks of the city of Sydney.

THE last number of the Bulletin of the Société d'Acclimatation of Paris contains an interesting and important report on the

International Fishery Exhibitions of Boulogne, Arcachon, and Havre.

AT the recent annual meeing of the Royal Cornwall Institution, a discussion arose on a paper read by Mr. Robert Blee "On the Comparative Health and Longevity of Cornish Miners," in the course of which the startling statement was made, that a death occurred every other day among the Cornish miners from the mode in which the men were raised from the pits.

PROF. DANIEL WILSON, of Toronto, publishes in the Canadian Journal an essay on "The Huron Race and its Headform," illustrated with a lithograph and many outline drawings. Prof. Wilson's investigations lead him to believe that the comprehensive generalisations of earlier American ethnologists, under the guidance of Dr. Morton, which led to the doctrine of a homogeneous cranial type for the American aborigines, have everywhere failed when subjected to the crucial tests of detailed observation, and that we everywhere find transitions from one to another and essentially distinct ethnical group. There is, he concludes, no longer an assumed American man, as distinct from every type in the Eastern Hemisphere as the Catarhine Simiada of the Old World from the Platyrhine group of New World monkeys.

ON Monday, August 21, between three and four o'clock in the morning, a large waterspout burst over the village of Ollon and the adjacent mountains in Switzerland. Great damage was done to the roads and vineyards, but no loss of life is reported.

A VIOLENT hurricane and some earthquake shocks are reported from the Island of St. Thomas, in the West Indies, on the 21st of August. Hundreds of houses were destroyed, and over 150 persons killed or wounded.

FROM Indian sources we learn that the rainfall in Bombay this season is generally less than half the average of former years. A VIOLENT typhoon raged at Kobe in Japan, on the 4th of July. Many vessels were wrecked, and about 400 lives were lost. Great damage was done to property on sea and on land.

THE news of most terrible earthquake shocks and volcanic disturbances comes to us from the Philippine Islands. In the small island named Camiguin, near to Misamis, for some months past a succession of most violent earthquakes has been experienced, causing crevices, &c., in the open country. On the 1st of May, about five o'clock in the evening, the earth burst asunder, and an opening was formed 1,500 feet long. Smoke and ashes, earth and stones, were thrown up and covered the ground far and near. At about seven o'clock, as darkness was coming on, this crater burst into activity with a loud explosion, followed by a shower of lava and ashes. About 150 persons were destroyed. The eruption of the new volcano has since been so tremendous that the inhabitants have forsaken the island, and of the 26,000 previously there, not 300 are left. Camiguin is only about thirtysix miles in circumference, and was very productive in abacá (the Manilla hemp) yielding annually from 30,000 to 40,000 piculs, or more than a tenth of the produce of the world. There is little hope of the island ever being again reoccupied or cultivated.

THE American Journal of Microscopy recommends, as the best plan of collecting diatoms in large quantities, to tie a thin, fine piece of linen over the faucet of the hydrant in the evening, and allow a small stream of water to pass through it all night. In the morning take off the cloth and rinse it in a little water in a goblet. When ready to examine, take a drop of water from the bottom of the goblet with a small pipette, or glass rod, and place it on a flat slide, or a slide with a concave depression, holding a few drops. Then, with a power of 100 or 350, sweep the field, and you will be rewarded with the sight of a wondrous collection of beautiful and unique forms.

THE BRITISH ASSOCIATION MEETING AT EDINBURGH

SECTION A.

Report of the Tidal Committee, by Sir W. Thomson.

A

He stated that the work performed for the Tidal Committee since the last meeting of the British Association had consisted chiefly in the evaluation of tide components in a similar manner to that described in the previous reports. Mr. Parkes having again placed the tracings of the curves of the Kurrachee (Manora) self-regulating tide gauge at the disposal of the committee, a second year's observations had been read off and completely reduced. In addition to the tide components evaluated for Liverpool and Ramsgate, others had been introduced to correct the lunar diurnal (declinational) tides for parallax. Those components had been found to have sensible values for Kurrachee, where the diurnal tides are comparatively large. The solar elliptic semidiurnal components had also been included, now that two complete years' observations were available. The comparison between the calculated and recorded heights from Liverpool not being considered as good as might have been expected from the labour bestowed on them, it was determined to continue the analysis of the Liverpool tides, with the view, if possible, of detecting the cause of the largeness of some of the differences. It would be seen on comparing the results contained in the previous report with the results arrived at, that the chief tides (the lunar and solar semi-diurnal) are now more retarded by about 4° than during the year previously analysed. The calculated heights in the comparison should therefore more nearly represent the heights about eight minutes after the hours assigned to them. An examination of the differences would show this to be the case. fresh calculation and due allowance made for atmospheric pressure would doubtless very considerably reduce the discrepancies. The gradual increase in the height of the mean level of the water, probably arising from the filling in of the bed of the river, and consequent increase of friction, would account for some portion of this increased retardation. There was a very violent rise in the mean level for the year 1868-69, amounting to four-tenths of a foot. It, however, in the following year, had again subsided to almost its anticipated height. The uncertainty in the mean level of the water is an element which must at times seriously affect the differences between calculated and recorded heights, in any method of computation of heights from a fixed datum. It was very much to be regretted that the authorities at Liverpool had chosen the George's Landing-Stage for a tide float, affected as it must be (sometimes to a considerable extent) by the evervarying weight it has to bear. This would affect the whole of the tide components evaluated, but more especially the solar components, and will account for the different values of the solar semi-diurnal tide, which, judging from the corresponding_lunar component, should agree within much narrower limits. It was therefore thought that, should it be determined to again discuss the Liverpool tides, it would be better to take the tide curves as self-registered at Helbie Island, at the mouth of the Dee, in preference to those of the George's Pier. The Helbie Island tide curves, it was considered, would give much superior results. Through the kindness of the United States Coast Survey Office, two years' tide observations, taken at Port Point, San Francisco Bay, California, had been received. Here again there was an abrupt diminution in the height of mean level for the first two years. It having come to the knowledge of the Tide Committee that the United States Coast Survey Office were in possession of a series of hourly tidal observations, taken at Cat Island, in the Gulf of Mexico, and which were of a very remarkable and interesting character, it was thought a favourable opportunity of testing the value of the harmonic analysis for the evaluation of the components of the tides of this place, which appeared very complicated and peculiar. Application having been made, a series of about thirteen months had been received, and were now in course of reduction. It was extremely interesting to find that, although the lunar and solar semi-diurnal tides were very small in value, the series of means from which they were obtained were extremely regular and good, and the consequent determination of the phase of spring tides from their respective epochs was probably correct within a few minutes. The proportion between the amplitudes of the lunar and solar semi-diurnal tides was the nearest to equality yet obtained, being in the ratio of 11 to 6. The proportion between the lunar and solar diurnal (declinational)

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