the steam from a little copper, f, placed at some distance from it.

The arrangements we have just briefly described enable a difference of readings between the air thermometer and the mercurial thermometer to be determined to nearly the hundredth of a degree.

From the descriptive summary thus given it will be seen how important is the new and remarkable international establishment now really established in the neighbourhood of Paris. It remains to add a word regarding the benefits which the labours of this institution are calculated to yield and the phases they have actually assumed.

The signing of the Metre Convention of 1875 will necessarily be followed in the near future by the adoption of the metric system on the part of all the nations of the civilised world. The universal introduction of a uniform

system of weights and measures, by establishing a new bond between people and people, and by promoting international relations, will undoubtedly prove a powerful factor in the interests of civilisation. This, however, is not the only, nor even the principal, interest of this international work. It was not necessary, it may be properly asserted, for the purposes of commerce and industry, to create a collection of such complex and perfect instruments and machines. More than anything else the interest of the labours of the bureau is scientific. Science will more and more cease to rest content with close approximations; in all possible branches it craves rigorous exactitude, it aims at precision. The International Bureau will furnish science not only with standards of measurement exactly controlled and verified, but also with a great number of physical constants determined with the greatest care and under conditions as perfect as possible.

Among all the sciences the one which will reap the greatest benefit from the new institution is geodesy. In fact one of the greatest drawbacks to an exact knowledge of the figure of our globe is just the uncertainty still prevailing in regard to the relative values of the measures which, having been employed for the measurement of the different bases, have served as points of departure for triangulations executed on various points of the earth's crust. The minute study of these measures, centred henceforth in the laboratories of Breteuil, will assuredly cause the troublesome discrepancies to vanish, and will offer a surer basis for the labours of geodesists. As much may be said for the study of the variations of gravity by means of the pendulum. The International Commission have decided on taking as the point of departure for the new metric units the standards already existing, that is, the metre and the kilogramme of the archives of France in their actual state. This decision ought to receive unqualified approval. While rendering full homage to the great and valuable

idea, formed at the end of last century, that the basis of universal measurements must be sought in the dimensions of the globe occupied by the human race, it ought also to be understood that for the present day the pith of the matter does not centre in the metre being a few microns (millionths of a millimetre) longer or shorter. The great point is that the whole world possess the same metre, and that the copies distributed be all perfectly equal to the standard, or rather rigorously determined in relation to that standard. To demand over and above that the length of the metre tally exactly with its theoretic definition would assuredly be demanding that the metre be subjected to periodical retouchings and modifications in order to make it keep pace with the progress of science, which would be the very worst of inconveniences for a fundamental unit.

This point settled, the next thing was to make an international metre and kilogramme,-copies, viz. as exact as possible of the metre and the kilogramme of the archives,

but presenting a greater guarantee than the originals in regard to their indefinite conservation and precision of comparisons, and which, being the common property of all the signatory nations of the Convention, should be preserved at the International Bureau, and serve henceforth as prototypes and points of departure in the system of weights and measures for the entire world.

The task next following was to make a sufficient number of metres and kilogrammes for distribution among the contracting Governments, after they had been compared with the international standards.

The choice of the material of which the new standards should be constructed, the form to be imposed on them, the nature and arrangement of the designs, the processes to be employed in the comparisons, and a host of accessory questions connected with the preceding mattershave all been the subject of long and learned deliberations, in which, besides the International Committee, the French section of the International Commission, composed of the best qualified French authorities, have played a great part. Even with the utmost possible brevity it would take too long to pass each of these points in review. Suffice it to say that the material adopted for the new standards, as much for the metre as the kilogramme, is platinum alloyed with a tenth part of iridium, which will impart to it greater hardness and resistance. The labours which the choice of this material has called forth have given rise to remarkable improvements in the mode of working and purifying the platinum and the metals with which it is found allied in the ore. It is impossible to recall them without at the same time bringing to remembrance Saint-Claire Deville, who with indefatigable zeal devoted the last years of his life to this pursuit.

The form fixed on for the netre is that of a bar, the section of which has the shape of an X or rather an H, the legs of which would straddle towards the top and towards the bottom. This form, calculated to supply a maximum rigidity for a given quantity of material, offers various other advantages on which we cannot now enlarge. It is 102 m. in length, and on the upper surface of the transversal limb (that is, on the neutral surface of a deflected beam) are traced two very fine lines, the distance of which at zero represents just the length of the metre. It is then a metre à traits. The metre of the archives, on the other hand, is a metre à bouts, that is, a bar measuring from one extremity to the other exactly the length of a metre. The metre is then defined by the distance at zero between the middles of the two terminal planes.

The comparisons between the international metre and the metre of the archives have been made at the Conservatoire des Arts et Métiers; those between the international kilogramme and the kilogramme of the archives have been made at the Observatoire. These labours, lasting no less than several months, have been performed by the care and under the direction of a mixed Commission composed of members of the International Committee and of members of the French section, under the presidency of M. Dumas, perpetual secretary to the Academy of Sciences, which represents France on the Committee. The fabrication of the national standards is in course of execution, and the definitive comparisons will shortly be able to be entered on.

NOTES

WE regret to announce the death of Dr. Oswald Heer of Zurich, the well-known paleontologist, at the age of seventy-five years. In his earlier years Dr. Heer devoted himself to entomology. We hope to give some notice of his life and work in our next number.

THE works in connection with the erection of the Ben Nevis Observato y are so far forward that the formal inauguration of the

With the view of

Observatory was to take place yesterday. stimulating public interest in the Observatory, there has just been published a small handbook giving an account of its origin, and describing the objects it is intended to promote. Mr. George Reid, R. S.A., has contributed attractive drawings of Ben Nevis

from the sea, and of the Observatory building; from Dr. Archibald Geikie have been obtained bird's-eye views of the scenery visible from the mountain top; and there is also inserted an excellent map, in which the new bridle-road is laid down and the configuration of the district indicated by nmerous contour lines. From a statement given as to existing high-level meteorological stations in other parts of the world, it appears that America maintains two such posts-namely, Pikes Peak, 14,151 feet, and Mount Washington, 6286 feet; while France can claim

four, ranging from 3989 to 12, 199 feet; and Italy three, of which the highest is 8386, and the lowest 7087 feet. Russia has one as high as 3787 feet, and Switzerland two, of 7505 and 2875 feet respectively. The highest in this island, so far, would seem to be Hawes Junction, 1135 feet, and Dalnaspidal, 1450 feet. Ben Nevis gives an elevation of 4406 feet, and, as has been repeatedly explained, important results are expected from the comparisons it will enable meteorologists to make between the state of the atmosphere at that height and the conditions prevailing at sea level. No time will now be lost in commencing the work of the Observatory, which has been intrusted to Mr. R. T. Omond, with Mr. Angus Rankin, and another yet to be appointed, as assistant observers. During the winter months the summit of the Ben may for weeks together be inaccessible; but certain observations will be daily communicated by means of the telegraph now being laid by the Post Office.

THE announcement of the publication of the Berlin Catalogue of Zonal Stars will have the effect of postponing the publication of the French catalogue, for which a credit of 400,000 francs had been asked from the Budget Commission.

THE President of the Berlin Geological Society has received a telegram from the Pentland Firth announcing the safe return of the German schooner Germania, which carried the German Polar ob erving party from the Gulf of Cumberland, where it has spent a year in successful observation and research.

WE have received a telegram from Herr Augustin Gamel of Copenhagen, in which he informs us that the Dijmphna anchored at Vardö, Norway, on October 11, all being well on board.

THE Russian Geographical Society is taking an active part in the International Congress which is to be convoked by the United States for the unification of the meridian. Delegates from the Academy of Sciences and from the Russian Ministries of War, and Posts and Telegraphs, will constitute a Committee at St. Petersburg, and the conclusions of this Committee will be supported at Washington by one or more Russian delegates,

WE learn from the annual reports of the West Siberian and East Siberian branches of the Russian Geographical Society (published in the Izvestia) that the East Siberian branch busily continues the exploration of the very rich remains from the stone period around Lake Baikal. The valley of Tunka, which seems to have been an immense workshop for the fabrication of quartz, jade, and nephrite implements, has been visited again by M. Vitkovsky, as well as the valley of the Angara. This last consists of a succession of large plains separated by narrow gorges; the former was occupied during the Post Pliocene period by a series of lakes, and subsequently it was the abode of a numerous population of the Stone period. M. Agapitoff discovered also a place on the Steppe of Ust-Unga which must have been a large work-hop for the fabrication of stone-implements, pieces of which cover the steppe over a space of more than twelve miles; thousands of implements could be collected

PROF. NORDENSKJÖLD has presented a meteoric block, which he found in 1870 at Greenland, to the Helsingfors University, where it has just arrived from America. Its size is not great, only one foot in height, but it is very heavy. It bears the fol. lowing inscription in English: "Terrestrial native iron. Ovipak, Greenland. Brought by A. E. Nordenskjöld." In presenting this unique specimen to the University the Swedish explorer writes:-"During my journey to Greenland in 1870, I found at Ovipak, on the Disco peninsula, several large blocks of iron which were brought home the year after by one of the naval steamers. On arriving there they were equally divided, as far as possible, into three parts, of which one became Swedish, the other Danish, and the third my property. To the latter belongs the block which I present to you, its weight being about 10,000 lbs. The same has, since 1876, when it was exhibited in Philadelphia, been deposited in Washington. As may be generally known, a fierce controversy has raged as to the nature of these blocks, some authorities maintaining that they were of meteoric, others of terrestrial, origin, a question on which opinions certainly may be divided. However this may be, it is certain that these blocks, whether as a specimen of the cosmic matter in the universe, or of the earth's interior, are of excep. tional interest, and may be considered to be valuable gems in any museum. To me personally this discovery is enhanced in value, as it enables me to present a testimony of my gratitude and affection to the institution where I received my first scientific education, and passed the most important period of my life." The block is to be kept out in the open air, as it has been discovered that these stones waste away in a room.

MR. D. MORRIS has in the press a work which will be shortly published, entitled "The Colony of British Honduras, its Resources and Prospects; with Particular Reference to its Indigenous Plants and Economic Productions." This work will include the results of Mr. Morris's travels in British Honduras, and throw a new light on many points connected with the climate, the flora, and the resources of this little known British dependency. The publisher will be Mr. Edward Stanford.

MESSRS. W. H. ALLEN AND Co. will publish shortly "The Influence of the Sun on Natural Phenomena," by A. H. Swinton, author of "Insect Variety."

THE green sun referred to last week as observed in India was also observed in every part of Ceylon from September 9 to 12. One correspondent writes as follows to the Ceylon Observer :-"Puleadierakam, September 12.-I write this from the above place on my way to Trincomalee, being much interested to learn whether the same phenomena exist throughout the island. The sun for the last four days rises in splendid green when visible, i.e. about 10° from the horizon. As he advances, he assumes a beautiful blue, and as he comes further on looks a brilliant blue resembling burning sulphur. When about 45° it is not possible to look at it with the naked eye; but, even when at the very zenith, the light is blue, varying from a pale blue early to a bright blue later on, almost similar to moonlight even at midday. Then, as he declines, the sun assumes the same changes but vice versa. The heat is greatly modified, and there is nothing like the usual hot days of September. The moon now visible in the afternoons looks also tinged with blue after sunset, and as she declines assumes a most fiery colour 30° from the zenith. The people are in terror at these phenomena, some even expecting the end. Can this be the result of the eruption in the Sund

A TERRIBLE earthquake occurred on Tuesday near Cheshmeh, a small town on a peninsula on the coast of Anatolia, and about twelve miles from the Island of Scio. Of late there have been several earthquake shocks in the pashalic of Anatolia and in other parts of Asia Minor, but it is to be feared that Tuesday's event eclipses all recent shocks in the devastation it has caused. It appears that the whole peninsula, from Smyrna to Cheshmeh, together with the neighbouring Island of Scio, was violently convulsed. The greatest destruction has been wrought in the western half of the peninsula between Cheshmeh and Voulra. All the villages in this district are destroyed, being nothing more than heaps of ruins. The wretched inhabitants had no time to escape, and upwards of 1000, it is estimated, have perished, while many others are injured.

AT 11.20 p.m. October 9 a slight shock of earthquake was felt at Irkutsk, Siberia. Several shocks of earthquake were felt on the roth in the afternoon throughout the whole of Northern Moravia. The oscillations lasted on each occasion from one to two seconds. The most violent shock occurred at Olmütz. Telegrams from Cilli, in Southern Styria, show that there were severe shocks felt there about an hour earlier than at Olmütz. On the same morning, too, there was a shock at Agram, lasting two seconds. A strong shock of earthquake, lasting fully eight to ten seconds, was also felt at Chios. The shock was felt at Syra, on the Dardanelles coast, and at Smyrna.

A WELL attended meeting of science and art teachers was held at the Birmingham and Midland Institute on Saturday last. On the motion of Prof. Tilden (who presided), seconded by Mr. E. R. Taylor of the Birmingham School of Art, it was resolved "That in the opinion of this meeting it is desirable to establish for Birmingham and the district a branch of the National Association of Science and Art Teachers." Among the objects of such an association it was mentioned would be the improvement of science and art teaching by discussions of methods of teaching and modes of demonstrating important scientific laws. A provisional committee was appointed, with Mr. C. J. Woodward as honorary secretary.

PRINCIPAL DAWSON asks us to state that in our report last week of his paper at the British Association (p. 579), the word relatives in the title should be relations, and that not tin ore but iron ore occurs in the Laurentian.

THE additions to the Zoological Society's Gardens during the past week include a Ruppell's Parrot (Paocephalus rueppelli ? ) from East Africa, presented by Dr. George L. Galpin ; a Malabar Parrakeet (Palæornis columboides) from Southern India, presented by Mr. F. W. Bourdillon; two Pileated Jays (Cyanocorax pileatus) from La Plata, presented by Mrs. J. W. Hammond; two Buzzards (Buteo vulgaris), a Hobby (Falco subbuteo), European, presented by Capt. H. Linklater; a Tiger Bittern (Tigrisoma brasiliense) from South America, presented by Mr. Joseph H. Cheetham, F.Z.S.; a Turtle Dove (Turtur communis), captured at sea, presented by Mr. W. M. Brown; five Long-nosed Vipers (Vipera ammodytes), a Viperine Snake (Tropidonotus viperinus), European, presented by Lord Lilford, F.Z.S.; a Macaque Monkey (Macacus cynomolgus) from India, a White-fronted Capuchin (Cebus albifrons) from South America, two Michie's Tufted Deer (Elaphodus michianus 8 8), an Elliot's Pheasant (Phasianus ellioti 8) from China, deposited; two Eyras (Felis eyra), a Red-vented Parrot (Pionus menstruus) from South America, a White-fronted Amazon (Chrysotis leucocephala) from Cuba, two Royal Pythons (Python regius) from West Africa, purchased; a Collared Fruit Bat (Cynonycteris collaris), born in the Gardens.

THE MOVEMENTS OF THE EARTH'

I.-Measurement of Space

IN proceeding to deal with the application of the various branches of physical science to the investigation of those phenomena which lie beyond the earth, there is a very large field from which to make choice of a subject which will show, now the application of one branch of science, and now the application of another, and bring us, in this way, somewhat nearer to the truths and the beauties which lie in the most distant realms of space for all who will take the trouble to look for them. But perhaps it may be more desirable to select that part of the subject which, so to speak, lies nearer home, and endeavour to point out how, by means of the application of principles, and methods, and instruments which are generally familiar, and which at all events are of daily use, the various movements with which our planet is endowed may be studied, not only with reference to the phenomena themselves, but with reference also to the causes which lie at the bottom of them.

The various branches of knowledge which will have to be drawn upon in furnishing the materials necessary for this inquiry were really started long before it was imagined that the earth had any movements at all; but still, on the whole, the growth of the knowledge of its movements has been so beautifully continuous, that we cannot do better now than consider historically the way in which those sciences have grown up, which enable us to make certain measurements, and to get out correctly certain quantities, which must nece sirily lie at the bottom of any sound knowledge.

What particular things do we want to measure? It has been already said that when the sciences to which attention will have to be called later on were founded, very few people on this planet knew that it moved at all, but it is now generally known that the earth does move. It will be obvious however that, whether the earth moves or not (and that may be considered still a moot question), if we wish to form a basis for our judgment in any direction, we must be able to measure time and space. It has been well said that "time and space are the moulds in which phenomena are cast;" for when it is de-ired to gain any useful knowledge concerning any fact, the relation which it bears to the things around it, and the time of its occurrence must be known, and that is the only thing an astronomer tries to do when he is investigating that portion of his subject to which we must first turn our attention. We will begin then by considering those measurements of space which are of the first importance to the astronomer. I do not here refer to the ordinary fam liar measurement of inches, yards, and miles, but to the measurement of angles, and it will be well to get a good no ion of this angular measurement as soon as possit le.

through B and B to B'. It will then have travelled half the cir. cumference of the circle CDE F, but civilised people, in order to get perfectly clear notions about this measurement, and to be able to tell each other what particular measurement they have made in this way, instead of talking of a circumference merely,

There is no special necessity for dividing the circle into 360 parts, but the greatest number of people have made that division, and it is still continued to be done. When the Chinese began to make circles they divided them, not into 360 parts, but into 3651. Now there was a great advantage, and a great disadvantage about that. The advantage was that this number of divisions in the Chinese circle was the same as the number of days in the year; the disadvantage was that they were not dealing with whole numbers, and their 3651 was not such a convenient number to halve and quarter, and so on, as is 360. In quite recent times it has been suggested that 400 parts should be taken instead of 360, but that is a suggestion which up to the present time has not been acted upon.

We have then an angle defined as the inclination of two straight lines starting from a centre; if we get one of these lines traversing an entire circumference, the other remaining at rest, the travelling line will have traversed 360°; we have what is called a right angle when one of the lines has been separated from the other through a quarter of a circumference—that is, 90°. This is the fundamental idea of angular measurement, the only measure. ment of space with which we shall have to deal at present.

For instance, if a little ivory rule be opened, its two parts become inclined to each other, and inclose what is known as an angle. That angle may be made large or small by opening and closing the two parts, A and B (see Fig. 1) of the rule. Suppose the rule to be shut, the point on which it turns being in the centre of the circle, CDEF, and that, whilst A remains at rest, B is made to travel successively

Report of Lectures to Working Men given at the Royal School of Mines by J. Norman Lockyer, F.R.S.

and of certain rough divisions of it, have divided all circles into 360 parts called degrees, and say that the travelling part, B, of the rule has travelled through not a quarter, or a half circumference, but through 90 and 180 degrees respectively.

Why are these measurements of space required? For the reason that when we are dealing with the heavenly bodies and seeking to define the position of any object, two facts at least are required to be known before its exact position can be determined. An observer going out at night upon an extended plain would see some celestial bodies near where the earth meets the sky all round, which is called the circle of the horizon, and he might happen to see another body exactly overhead, in what is called the zenith. In passing from this zenith to the horizon it will be obvious that a quarter of a circumference is traversed (see Fig. 2). That distance may therefore be divided into 90°.

Similarly in passing from the eastern horizon to the western horizon half a circumference is travelled over. This distance therefore is divided into 180° of angular measurement in the same way that the half of the circumference traversed by the travelling rule was divided into 180°.

This

Now if it can be ascertained of any body that it is exactly in the zenith, the position of that one body has been definitely stated for the particular time at which the observation is made. But consider the case of another body not in the zenith. Suppose that the lines, the one A B (see Fig. 2), passing from the observer to the object, and the other, AC, passing from the observer to the horizon, inclose an angle of 45°. angle is called the star's altitude. But to say simply that the altitude of a star is 45° does not sufficiently define its position. Let the reader imagine himself to be standing in the Albert Hall. He knows that he may look up and see rows of panes of glass and ornamented work running around the hall at different heights above the floor. He may also notice, let us say, various series of ornamentation arranged vertically from floor to roof. Now suppose it were desired to define the position of any one pane of glass or piece of ornamentation in any one of these horizontal or vertical rows. It is obvious that to say of any pane of glass at one level that it is at a certain height above the floor will not suffice, for all the panes of glass in that row are at the same