By whatever cause so great a difference in the barometric pressure in the different regions might be produced, it may be shown from the principles of dynamics that the equilibrium would be restored in a very short time, if there was not some constant force tending to drive the atmosphere from the polar regions towards the equator, or from the centre of the cyclone to the exterior, and to keep it in that position. Such a force may be found in the influence of the earth's rotation. In a paper by the writer in the Mathematical Monthly in 1865, published in Cambridge, U.S., a full abstract of which was also published in the January No. of Silliman's Journal for 1861, the following very important principle was demonstrated-In whatever direction a body moves on the surface of the earth, there is a force arising from the influence of the earth's rotation, which tends to deflect the body to the right in the northern hemisphere, and to the left in the southern hemisphere. This force, which is the key to the explanation of many phenomena in connection with the winds and currents of the occan, does not seem to be understood by meteorologists and writers on physical geography. We see it frequently stated that the drift of rivers and currents of the ocean running north or south always tends to the right in our hemisphere, and that a railroad car running north or so th presses to the right; and this is the case. But the same is true, and to exactly the same amount, of a current or of a railroad car running east or west, or in any other direction. The amount of this deflecting force, when the velocity of the body is small in comparison with that of the earth's rotation, is expressed by 2. cos g; in which is 289 n the lineal velocity of the body relatively to the earth's surface, that of the earth's rotation at the equator, the angle of polar distance, and g the force of gravity. If the velocity is expressed in miles per hour, the expression in g; that is, for each mile

round numbers becomes

I

ข

I

I

5,000

ข

V cos 0 i50,000 of velocity per hour, the force is of gravity, mul150,000 tiplied into the cosine of the polar distance. Hence a railroad car on the parallel of 45° north, running in any direction at the rate of forty miles per hour, presses to the right with a force equal to about part of its weight. The effect of this deflecting force upon what Mr. Stevenson calls the barometric gradient is easily estimated. Since the strata of equal pressure of the atmosphere, so far as this force is concerned, must be perpendicular to the resultant of this force and gravity, the sine of inclination of any such stratum to the earth's surface must be cos 150,000, and the change in barometric pressure for any given distance is equal to the weight of a column of atmosphere of a height equal to the change of level of the stratum of equal pressure, and of a density equal to that at the earth's surface. The barometric gradient, then, as expressed by Mr. Stevenson, for any distance d expressed in v cos e d x 30 inches; putting five miles for the 5 × 150,000 height of a homogeneous atmosphere, and thirty inches for the pressure at the earth's surface. Round numbers are used throughout, since it is only the order of the effects we wish to determine, and not their exact amount.

miles is

According to all observations, there is a steady and very strong wind blowing all around the earth in the middle and higher latitudes of the southern hemisphere, with a velocity of at least twenty-five or thirty miles per hour at the surface of the ocean, and this is perhaps much greater in the upper strata of the atmosphere. If at the parallel of 50° we suppose the velocity of the wind v to be thirty miles per hour, the preceding expression of the barometric gradient for a distance d of 5 or 350 miles, using the

cosine of 40°, is 0'33 inches of mercury. By reference to § 113 of Mr. Buchan's Meteorology, it will be seen that the barometric gradient for that parallel is only 0.28. inches for 5 of latitude, and that this is about the maximum gradient in the southern hemisphere. Hence a velocity less than 30 miles per hour at the surface of the sea, especially if we suppose that it increases in the higher regions, is sufficient to account for this maximum barometric gradient; and, according to observations, 20 or 30 miles per hour for the wind in that region is no unreasonable assumption. The eastward velocity of the wind in the different latitudes being known, and, consequently, the corresponding barometric gradients, the difference of barometric pressure between any parallel near the pole and one toward the equator, is readily obtained by integration. As the wind near the equator is toward the west the deflecting force there is toward instead of from the pole, and hence the greatest barometric pressure is about the parallel of 30°, and there is a slight depression at the equator. The deflecting force and the consequent depression are small, then, on account of the small value of near the equator.

Since there is more land and mountain ranges in the northern than in the southern hemisphere to obstruct the eastward motion of the atmosphere, its velocity is not so great, and consequently the polar depression is much less there than in the southern hemisphere. According to Mr. Buchan the barometric depression in the Arctic regions is much greater in the northern part of both the Atlantic and Pacific oceans, than it is in the same latitudes on the continents. The explanation of this is, that the eastward velocity of the atmosphere over the oceans being much greater than it is on the continents, where it is obstructed more by friction and mountain ranges, the force driving the atmosphere from the poles toward the equator is less, and consequently the barometric pressure is less in the northern part of both oceans than it is on the continents in the same latitudes.

Upon the relative strength of the forces tending to drive the atmosphere from the poles towards the equator, depend the positions of the equatorial and the tropical calm belts. This force being strongest in the southern hemisphere on account of less resistance from friction and mountain ranges, the mean position of the equatorial calm belt is a little north of the equator, and the positions of the others a little farther north than they would otherwise be. The prime motive power also in both hemispheres being the difference of density of the atmosphere between the polar and the equatorial regions, arising from a difference of temperature and of the amount of aqueous vapour, during our summer when this difference is less than the average in the northern hemisphere, and greater in the southern, these calm belts are forced a little north of their mean positions. Of course, just the reverse of this happens during our winter; hence we have an explanation of the annual variations of the positions of these belts.

In the case of cyclones, the atmosphere at the earth's surface being forced in from all sides towards the centre, by the force arising from a difference of density of the atmosphere in the central and exterior parts, it cannot, on account of the deflecting force which has been explained, move toward the centre, without, at the same time, receiving a gyratory motion around that centre. Neither can it have a gyratory motion without also having a motion towards that centre, since in that case there would be no force to overcome the frictions of gyration. Hence, neither the radial theory of Espy, nor the strictly gyrating theory of Reid and others, can be true, though either of them may be approximately so in special cases. But the gyratory part of the motion is not caused by the motion of the atmosphere from the north and south only toward the centre of the cyclone, as stated by Mr. Buchan and others, but equally by the different parts moving in from all sides,

since in whatever direction they move toward the centre there is the same deflecting force, either to the right or the left according to the hemisphere.

The motion of the atmosphere being in a spiral toward and around the centre of the cyclone, the deflecting force depending upon the earth's rotation, at right angles to the direction of motion, being resolved in the directions of the radius of gyration and tangent, the latter overcomes the friction of gyration, and the former causes a pressure from the centre, decreasing the height of the strata of equal pressure in the cyclone, and consequently diminishing the barometric pressure. The barometric gradient of a cyclone is estimated in precisely the same way as in the case of the hemispheres, using for the lineal velocity of gyration obtained by resolving the real motion into the directions of the tangent of gyration and of the radius. It has been seen that a velocity of 30 miles per hour gives a barometric gradient of of an inch in 350 miles on the parallel of 50. A gyratory velocity therefore of 100 miles per hour would give a barometric gradient of one inch of mercury in about 300 miles. The velocities of gyration being known at all distances from the centre of motion, and consequently the barometric gradients, the difference of barometric pressure between the centre and the exterior, so far as it depends upon the gyratory motion, may be obtained by integration. The effect of the centrifugal force of the gyrations is generally only a very small quantity of a second order, in comparison with the other, and the effect of it is entirely insensible, except in the case of small tornadoes, when the gyrations are very rapid close around the centre. In all the preceding estimates of the barometric gradient, it should be understood that the results belong merely to the force depending upon the earth's rotation, and to this must be added the part belonging to a difference of density of the atmosphere, which in the case of cyclones increases the gradient, but diminishes it in the case of the hemisphere. For the general motions of each hemisphere form a cyclone, with the pole as a centre; but having the denser instead of the rarer portion of the atmosphere at that centre. Hence the motions in any vertical plane through the centre are reversed, and it becomes what has been called an anti-cyclone. Cambridge, Mass.

WM. FERREL

RECENT MOA REMAINS IN NEW
ZEALAND
II.

THE
HE Moa's neck with the integuments attached, the
discovery of which was announced in my com-
munication dated April 3, has since then been forwarded
to this Museum for examination by Dr. Thompson, and
the following particulars may not be without interest to
your readers.

The total length of the specimen is 16.5 inches, and includes the first dorsal and last six cervical vertebræ with the integuments and shrivelled tissues enveloping them on the left side. The surfaces of the bones on the right side, where not covered by the integuments, are free from all membranes and other tissues, but are quite perfect and in good preservation, without being in the least degree mineralised.

The margin of the fragment of skin is sharply defined along the dorsal edge, but elsewhere it is soft, easily pulverised, and passes into adipocere.

The circumference of the neck of the bird at the upper part of the specimen appears to have been about 18 inches, and the thickness of the skin about of an inch.

The only indication of the kind of matrix in which it had been imbedded was a fine micaceous sand, which covered every part of the specimen like dust, there being no clay or other adherent matrix. On removing this sand with a soft brush from the skin, it was discovered to be of a dirty red-brown colour, and to form deep tranverse

folds, especially towards the upper part. The surface is roughened by elevated conical papillæ, from the apex of some of which springs a slender transparent feather barrel, never longer than half an inch. On the dorsal surface a few of these quills still carry fragments of the webs, some being 2 inches in length. From these it appears that the colour of the feather barbs was chesnutred, as in Apterix Australis, but that each barrel had two equal plumules to each quill, as in the Emu and Cassowary, andin this respect differed from the Apterix, the feathers of which have not even an accessary plumule. On the other hand the barbs of the webs of the feathers do not seem to be soft and downy towards the base as in the Emu. From the direction of the stumps of the feathers, it is evident that the portion of the neck which has been preserved is that contained within the trunk of the body, and which, in the natural position, has a downward slope, the conical end of the specimen being where the upward sweep of the neck of the bird commenced, which accounts for the absence of the trachea with its hard bony rings, none of which are found among the soft parts which have been preserved.

The integument was easily removed by dividing the few threads of dried tissue by which it was attached. The shrivelled-up soft parts thus displayed could not be clearly distinguished, but may be grouped as follows:-I. A strong band of ligamentous tissue connecting the spinous processes. 2. Inter-vertebral muscles and ligaments. 3. A sheath diverging from the lower part as if to enclose the thorax. The only bone besides the vertebra was attached to this sheath by its tip, the other extremity being articulated to the first dorsal.

Respecting the nature of the circumstances to which this remarkable specimen owes its preservation, I can only conjecture that the body of the bird must for a considerable period have lain on its side in water or a swamp, and that the portion immersed was thoroughly macerated, while the exposed parts were desiccated and shrivelled up; and that subsequently the whole remains were embedded in dry sand.

As a fact of some interest connected with the history of the Moa, I should mention that in December last, Archdeacon Williams informed me of the discovery of a series of enormous bird-foot marks on the surface of a layer of sand beneath a bed of alluvium at Poverty Bay. The specimens he collected for me have unfortunately gone astray, but others have been placed in the Museums in Auckland and Napier, and I have just seen a pencil rubbing from the latter, taken by Mr. Cockburn Hood, which leaves no doubt that they are the footprints of a bird like the smaller-sized species of Dinornis, the largest of these footprints being about eight inches in length. JAMES HECTOR

Colonial Museum, Wellington, New Zealand, May 15 [We exceedingly regret that we are unable to repro duce woodcuts of the beautiful illustrations by which Dr. Hector's article is accompanied.--- En.]

NOTES

WE are glad to learn that our anticipations last week with reference to the Australian observations of the Total Solar Eclipse of December next are being realised. The Royal Society of New South Wales is organising an expedition to Cape Sidmouth, a little south of Cape York. The President of the Royal Society of London has arranged that a few instruments of the newest construction shall be sent out from this country.

It perhaps is not so generally known as it ought to be that the Emperor of Brazil, now in this country, is an enthusiastic astronomer, and has an appreciation of the value of science which places him in the highest rank among reigning sovereigns. During the last week he has visited the Royal and Mr. Huggins's Observatory, and in a long interview with Mr. Lockyer has discussed the bearings of the recent solar discoveries.

of acid and one of alcohol. Given internally, or applied to the wound at a late period, it produces no effect. It is believed to act, not by neutralising the poison, but by causing contraction of the small vessels, and thus preventing its absorption.

THE following interesting account was published in Notes and Queries of August last year without eliciting any reply. Mr. Alexander Williams writes :-"As the Commissioner for Western Australia of the International Exhibition of 1862, I received from the Colonial Committee at Perth several specimens of native shields. The long narrow form of these implements of defence is common to all the Australian colonies I believe, but I cannot say whether the ornamentation is uniformly the same. But among the Swan River nation it consists of an oblong pattern (following the shape of the shield) composed of border within border, traced in different coloured paint. The late Mr. Christy called my attention to the exact similarity of these shields to those used by the natives of Central Africa—a similarity not only in shape and pattern but actually in the succession of colours in the pattern. How is this to be accounted for? It is possible (and no other theory seems admissible) that it is purely an accidental coincidence. It is perhaps not difficult of belief that the native mind in two races in all respects so utterly distinct should have hit upon the same shape and form of weapon to meet and throw off the common spear. It is even not very surprising that savages unacquainted with 'lines of beauty' should adopt the same crude form of ornamentation, but it is somewhat startling I think that they should have used apparently the same pigments, and very extraordinary as it appears to me that they should have adopted precisely the same succession of colours."

WHILST we have been literally overwhelmed with rain in this country for the last three months, it is interesting to hear that in Tientsin in China there was so little snow in the winter, and hardly any rain has fallen since, that the peasantry are complaining of the want of water, and consequent injury to the crops.

A SEVERE earthquake shock is reported from Brooklyn and Staten Island, New York, on the 19th of last month at about IO P.M. No great amount of damage was done, and the motion appears vertical rather than horizontal in character.

THE American Journal of Science gives a long report of the severe earthquake at Oaha, Hawaian Islands, on February 18 of this year. It commenced at about 11 minutes past 10 P.M., and lasted about a minute. The direction of motion was vertical, with a rocking movement N. E. and S.W. The usual roaring sound preceded the earthquake and was heard far out at sea. No earthquake wave is reported from any quarter, although the earthquake itself seems to have been felt on all the islands more or less severely. No unusual volcanic action is reported. Slight shocks were also felt on the 22nd and 24th of the same month. It should be noticed that a severe earthquake is reported from Chile on the 25th, and shocks were noticed in Peru on the 22nd and 23rd of February.

THE existence of certain plants only in limited districts is one of the most remarkable points of interest in connection with the problem of the distribution of species. Mr. Moggridge, in his valuable "Contributions to the Flora of Mentone," figures a very elegant species of Leucojum, of which no drawing had hitherto been published. "It is believed to have but one habitat on the face of the earth, claiming only a small strip of rocky shore reaching from Nice to about two miles east of Mentone. Leucojum hyemale grows in a stony soil, and out of the cracks of the hardest limestone rocks at Port St. Louis, Cape Veglio, on the way to Monaco, and at some height on the Aggel mountain, besides other less abundant localities." We are not

aware whether this species has been introduced to English gardens, but it would be a very desirable acquisition. At Mentone it flowers in April.

THE Ant-eating Woodpecker (Melanerpes formicivorus) a common Californian species, has a curious and peculiar method of laying up provision against the inclement season. Small round holes are dug in the bark of the pine and oak, into each one of which is inserted an acorn, and so tightly is it fitted or driven in, that it is with difficulty extracted. The bark of the pine trees, when thus filled, presents at a short distance the appearance of being studded with brass-headed nails. Stowed away in large quantities in this manner, the acorns not only supply the wants of the woodpecker, but the squirrels, mice, and jays avail them. selves likewise of the fruits of its provident labour.

DR. GEORGE STUCKLEY gives an interesting account of the Western Mole (Scalops Townsendii), which occurs in the Oregon and Washington Territories. He kept a specimen for some time in a box, at the bottom of which was a quantity of rich black loam. When disturbed it instinctively endeavoured to escape by burrowing in the earth of the box, using its long-pointed nose as a wedge to pioneer the way. The excavation was performed by its broad stout hands, which, surmounted with their long sharp claws, seemed admirably adapted for the purpose. The fore paws were worked alternately as in swimming, the hind feet acting as propellers. Although the earth in the box was soft and friable, it was nevertheless a matter of astonishment to see how rapidly the little creature could travel through it. When he slept it was in a sitting posture, with the body curled forward and the neck strongly bent, so that the nose rested between the hind legs. He thus assumed the shape of a ball, evidently his ordinary position when asleep.

THE cultivation of the poppy in China, which has been more than once prohibited by Imperial edicts, appears to be increasing everywhere, and becoming a profitable trade. In Szechuen, where the climate is warm and the season early, two crops at least are produced on the same ground annually. The seed of the poppy is sown in February, the plants flower in April, and the fruits are so far matured by the middle of May, that the juice is collected, and the stalks removed and burnt directly after, but previous to this the second crop, which may be either Indian corn, cotton, or tobacco, is sown, so that almost by the time the poppy is cleared from the field the new crop makes its appearance. The profit derived from the cultivation of the poppy is not only the result of a fair market value and a ready sale, but also from the fact that much of the work in the plantation, especially the gathering of the juice, can be done by the children of the family. The scratchings or incisions being made in the capsules in the morning, the juice which has oozed out in the course of the day is collected in the evening, and after simply exposing it to the sun for a few days it is ready for packing. The seed not required for sowing is used for food.

ON THE RECENT SOLAR ECLIPSE*

I.

MY duty to-night, a pleasant one, although it is tinged with a certain sense of disappointment, is to bring before you the observations which were made of the recent eclipse in Spain and Sicily, to connect them with our former knowledge, and to show in what points our knowledge has been extended. In these observations, as you know, we had nothing to do with the sun as ordinarily visible, but with the most delicate phenomenon which becomes visible to us during eclipses. I refer to the Corona.

General Notions of the Corona

Let me, in the first place, show you what is meant by this *A Lecture delivered at the Royal Institution, Friday, March 17, 7871

I

term, and state the nature of the problems we had before us. have here some admirable drawings, which I will show by means of the lamp, of the eclipse that was observed in 1851 by several astronomers who left England in that year to make observations in Sweden, where the eclipse was visible. You must bear in mind that the drawings I shall bring to your notice were made in the same region, at places not more than a few miles apart." The first drawing was made by an observer whose name is a sufficient guarantee for its accuracy-I refer to Mr. Carrington-and when the sky was absolutely free from clouds. In the next diagram you will see the corona is changed. The bright region round the sun is no longer limited to the narrow border of light round the dark moon, as seen by Mr. Carrington, but it is considerably expanded. The third gives still a greater extension, although that picture was drawn within a quarter of a mile of the place where Mr. Carrington's was taken. And lastly, we have a drawing made by the present Astronomer Royal, of that same eclipse, through a cirrostratus cloud as unlike Mr. Carrington's as anything can possibly be. So that you see we began with a thin band of light about the moon, which would make the corona a few thousand miles high, and we end with a figure which Mr. Airy graphically likens to the ornament round a compass-card, and which gives the corona a height equal to about once and a half the sun's diameter.

I will next bring before you some drawings made during the eclipse of 1858, which was not observed in European regions, but in South America by two first-rate observers-one, M. Liais, a French astronomer, who was stationed at Olmos, in Brazil; the other, Lieutenant Gilliss, who was also there as a representative of the American Government, and observed some thousand miles away in Peru.

I will throw on the screen the appearances observed by these gentlemen, and I think you will acknowledge the same variations between their results, as to degree, while in one case we get a perfectly new idea of the phenomena-a difference in kind. I would especially call attention in the Olmos drawing to those extraordinary bundles of rays of wonderful shapes, which you see are o much brighter than the other portions of the corona. Such forms have been seen in other eclipses, but they are somewhat rare. The drawing made by Lieutenant Gilliss bears the same relation to that made by M. Liais as Mr. Carrington's did to the Astronomer Royal's; so that we may say that we not only get variations in the dimensions of the corona as seen at different stations, but that we furthermore get a strange structure mtroduced now and then in our drawing in regions where absolutely no corona at all exists in the other.

So much by way of defining the phenomena and giving an idea of the eye observations generally.

Let me now attempt to show you how the phenomena observed in the last eclipse bear upon the results which had been previously accumulated by means of telescopic and naked-eye observations, and by means of the polariscope and spectroscope.

I. TELESCOPIC AND NAKED-EYE OBSERVATIONS
a.-A Part of the Corona is undoubtedly Solar

The first use I propose to make of the telescopic and nakedeye observations of last year is to show you a photographic copy of an admirable drawing made by Mr. Brett, who, though unfortunate enough to see the sun only for a very short time, was yet sufficiently skilled to make good use of that brief period. This drawing will bring before you the fact that even when a large portion of the sun remained unobscured by the moon, Mr. Brett was enabled to see a dim ring of light round the unobscured portion, which since the year 1722 has been acknowledged, beyond all question, I think I may say, to represent something at the sun. It was observed in 1722 round the uneclipsed sun, and in more recent times by Mrs. Airy in 1842, and by Rumker 14 minute before totality in 1860, not to mention other instances. Therefore we have one observation made during this eclipse, confirming the old one, that in the corona there is a region of some small breadth at all events which is absolutely solar, and which it only requires a diminution of the solar light to enable us to

* Mr. Carrington observed at Lilla Edet, on the Grota River. The Astronomer Royal observed at (öttenburg The second drawing referred to was made by Pettersen, at Göttenburg; the third by a friend of the Rev. T. Chevallier, at the same place and I might have added another by Fearnley, taken at Rixhöit, in which the corona is larger than in any of the others. The series is most instructive. See Mem. R. A. S. vol. xxi.

b.-Rays, or Streamers, are added at Totality

The drawings made in all the eclipses which have been carefully recorded bring before us quite outside this narrow, undoubtedly solar region, observed before totality, as I have shown, and also by Mr. Carrington, and by Lieutenant Gilliss during totality in 1851 and 1858, extraordinary appearances of a different order. While in fact we have a solar ring from 2' to 6' high, we have rays of all shapes and sizes visible outside, in some cases extending as far as 4°, and in all cases brighter than the outer corona on which they are seen, the rays being different in different eclipses, and appearing differently to different observers of the same eclipse, and even at the same station. Here is a copy of a drawing made by M. Rumker of the eclipse of 1860, and I show it for the purpose of calling your attention to the fact that the two curious rays represented in it belong to a different order of things from those which we see in the rest of the corona From the beginning to the middle of the eclipse the east rays were the most intense. In the next drawing, which was made by the same observer, you see something absolutely new; and now the western side of the corona is the most developed; we have a new series of bright rays, and altogether it is difficult to believe that it is a drawing made by the same observer of the same eclipse.

The third drawing is a representation of the same eclipse by M. Marquez, who observed with a perfection of minute care which has scarcely ever been equalled: I bring it before you to show that the rays he saw were altogether differently situated. We may conclude then that the rays, a though extremely definite and bright-as bright or brighter than the other portions of the corona which are visible before totality, they being invisible before totality-appear different to different observers of the same eclipse, and to the same observer during different phases.

c.-They Change from Side to Side

I have already said that M. Rumker observed that from the beginning to the middle of totality the rays on the cast side of the sun were longest and brightest, and that from the middle to the end of totality the rays on that side of the sun where the totality ended were longest and brightest.

We will now carry this observation a step further, by referring to three drawings made by M. Plantamour in the same eclipse, that of 1860. In the first drawing we have the beginning of the total eclipse as seen in the tele-cope; with the naked eye naturally we should get the sun disappearing at the east or left-hand side, the moon moving from west to east; in the telescope things are reversed, and we have it right instead of left: and here we have the same thing that M. Rumker observed, namely, that when the eastern limbs were in contact, bright rays (M Plantamour saw three) were visible on the side at which the contact took place. When the moon was half way over the sun, two rays of reduced brilliancy were observed on that side, not necessarily in the same position as those first observed, but one of these has been abolished altogether; and on the other side of the sun, where totality was about to end. we have three rays gradually suggesting themselves : at the end of totality the rays visible at the commencement are abolished, and now instead of them and of those seen at the middle of the eclipse, we have a bran new set of rays on the side of the moon from whence the sun is about to emerge.

This observation I need hardly say is of considerable importance in connection with the f-ct that from the year 1722 almost every observer of a total eclipse has stated that there is a large increase of brilliancy, and an increase of the size of the corona on the side where the sun has just been covered, or is just about to emerge.

Now, what was there bearing on this point in the recent observations? I have here three drawings, which, though roughly done, you will see are of great importance side by side with those of M. Plantamour. These are drawings which have been sent in to the Organising Committee by Mr. Gilman, who lives in Spain, and who took considerable interest in the eclipse, and sent the results of his observations to England with the eclipse party when they came home; and it is of importance that you should see everything that Mr. Gilman has done. If you agree with this explanation of the square form of the corona, which was observed in Spain this year, it will explainl the quadrangular form observed in the corona in a good