ACCORDING to a telegram received in New York from Mexico, the Mexican Government has ordered the inhabitants of the villages in the neighbourhood of the town of Colima to abandon their homes and seek refuge elsewhere, as the volcano in the vicinity, which was recently in eruption, shows signs of fresh activity, and the country for miles around it is illuminated by the flames issuing from the crater.

THE census of 1890 in Austria-Hungary shows that the rate at which the population increased during the preceding ten years was very different in the two great divisions of the Monarchy. The increase in so-called Cisleithania was 7'9 per cent.; in Transleithania, 10.82 per cent. In the individual provinces the increase was very unequal. In Lower Austria it was 138 per cent., this high rate being due to the attractive force of Vienna. Then came Bukowina with 13.1 per cent.; Galicia, 104 per cent. ; Silesia, 6.5 per cent. ; Moravia, 55 per cent.; Bohemia, 5 per cent.; the Alpine Jands, from 32 to 36 per cent. ; and Tyrol, o'9 per cent. A different set of figures is yielded by the increase of the various nationalities. Among these the Poles stand highest, with 15 per cent.; then the Serbo-Croatians, 14 per cent; the Ruthenians, I per cent.; the Germans, 566 per cent.; the Czechs, 565 per cent.; the Slovenians, 3 18 per cent. ; and the Italians, under 1 per cent.

MR. HENRY LAVER records in the current number of the Zoologist the capture of a spotted eagle at Elmstead, near Colchester, on October 29, 1891. On that day a farm labourer saw a strange bird, evidently in an exhausted condition, alight in the field in which he was working. When he went after it, it rose, and flew about a hundred yards. He soon came up to it, and, after some little difficulty, from its pugnacity, captured it alive and uninjured, and in a few days sold it to a gipsy, who in turn disposed of it to Mr. Pettitt, the local taxidermist. Mr. Laver says its plumage appears to indicate good health, and that its appetite favours that idea. If any injury led to its capture, all marks of it have quite disappeared.

THE new instalment of the Transactions of the Leicester Literary and Philosophical Society (vol. ii. part ix.) contains an abstract of an interesting lecture by Mr. Harold Littledale, of the College, Baroda, on some of his experiences with big game in India. Mr. Littledale gave an especially good account of shooting in the Himalayas. The ibex and markhoor were found at altitudes varying from 10,000 to 20,000 feet, and could be obtained only by perseverance in the face of many dangers and obstacles. Of the markhoor (Capra megaceros), a splendid animal which is becoming increasingly rare, he obtained ten examples, and ibex had also fallen to his gun, with 45 inch horns the maximum development being about 52 inches. Various species of sheep also occurred, as the magnificent Ovis poli, which the lecturer had not yet met with, Ovis ammon, Ovis cycloceros, &c. The chamois was found commonly in the Himalayas, and Hodgson's antelope could be shot at elevations of 20,000 feet. Amongst the other mountain animals described were the snow leopard, Sikkim stag, and musk deer (Moschus moschiferus), with its tusks about 5 inches in length.

MR. W. H. ROSSER has written for the benefit of candidates preparing for the Board of Trade examinations a general explanation of what is usually known as the "Compass Syllabus." It is entitled "Compass Deviation: a Syllabus of Examination in the Laws of Deviation, and in the Means of Compensating it," and is published by Messrs. James Imray and Son. The pamphlet is to be regarded as an appendix to Mr. Rosser's "Deviation of the Compass considered practically."

MM. H. LÉVEILLÉ AND A. SADA, of Pondicherry, have started a new botanical journal with the title Le Monde des Plantes: Revue Mensuelle de Botanique. The first number appeared on October 1. It is published at Le Mans (Sarthe).

THE Council of the Owens College have published the first volume of "Studies in Anatomy." It is edited by Prof. A. H. Young, and presents a part of the results of investigations conducted in the anatomical department of the College during the last three or four years.

MESSRS. BAILLIÈRE, TINDALL, AND COx have issued a second edition of Dr. Edridge-Green's work on "Memory: Its Logical Relations and Cultivation."

A NEW edition of "Falling in Love: with other Essays on More Exact Branches of Science," by Mr. Grant Allen, has been published by Messrs. Smith, Elder, and Co.

MESSRS. BEMROSE AND SONS have issued a second edition of a "Hand-book to the Geology of Derbyshire," by the Rev. J. Magens Mello. The work has been rewritten, and is illustrated with a map and sections.

A CURIOUS compound of lead, sodium, and ammonia, Pb,Na. 2NH,, is described by M. Joannis in the current number of the Comptes rendus. M. Joannis has been studying the nature and reactions of the substance known as sodammonium, ob. tained by dissolving metallic sodium in liquefied ammonia. The deep blue liquid thus produced has been shown in a previous communication (see NATURE, vol. xliii. p. 399) to decompose slowly at the ordinary temperature into hydrogen gas and sodamide, a compound of the composition NaNH2, which M. Joannis isolated in the form of colourless crystals. That such a compound as sodammonium (NaNH3), really exists in the blue solution in liquefied ammonia would appear to be the most natural assumption from these experiments. The reactions of sodammonium now described lend additional support to this view. When a rod of pure lead is placed in a saturated solution of sodammonium in water, the reddish-brown liquid becomes rapidly blue, and finally assumes a deep green tint. A small quantity of hydrogen is evolved at the same time owing to the decomposition of a portion of the sodammonium into sodamide, as above described. The lead gradually disappears, and a solid substance possessing an indigo-blue colour is deposited. This blue substance is found upon analysis to consist of the compound Pb,Na. 2NH3, and would appear to be a sodammonium in which a portion of the sodium is replaced by lead. It dissolves readily in liquefied ammonia with formation of a solution possessing a bottle-green tint. It is not very stable, dissociating spontaneously on standing, with production of a grey substance very much resembling spongy platinum. Upon exposure to air it becomes warm owing to its rapid oxidation. It behaves in a When introsomewhat remarkable manner towards water. duced in small quantities at a time into ordinary water, the first portions dissolve completely, the oxygen dissolved in the water oxidizing the lead to litharge, which at once dissolves in the alkaline solution formed. As soon, however, as the oxygen in the water is used up, further additions of the substance result in the precipitation of black flocculæ of metallic lead. Another interesting reaction of sodammonium is that with metallic mercury, which behaves in an entirely different manner from lead. When the solution of sodammonium in liquefied ammonia is poured over a globule of mercury, rapid action occurs, with the ultimate elimination of the whole of the ammonia, and production of a sodium amalgam of the composition NaHgs, which has been obtained in well-formed crystals. This reaction is the more interesting inasmuch as M. Berthelot, from purely thermo-chemical considerations, has previously indicated the possible exi tence of such a compound of sodium and mercury.

THE additions to the Zoological Society's Gardens during the past week include a Sooty Mangabey (Cercocebus fuliginosus ¦ › from West Africa, presented by Mr. H. E. Dampier, J.P.; a Rufous necked Weaver- Bird Hyplantornis texter ) from West Africa, presented by Commander W. M. Latham, R.N., F.Z.S.; a White Stork (Ciconia alba, European, presented by Mr. Walter Chamberlain, F.Z.S.; eighteen Grenadier Weaver Birds (Euplectes oryx), ten Golden-backed Weaver Birds (Pyromelana aurea, nine Black-capped Weaver Birds (Hyphantornis nigriceps), four Red-bellied Waxbills (Estrelda rufiventris), three Triangular-spotted Pigeons (Columba guinea), four Dwarf Chameleons (Chamaleon pumilus) from South Africa, presented by Mr. R. W. Murray.

OUR ASTRONOMICAL COLUMN. JUPITER AND HIS FIRST SATELLITE.-A series of observations of spots and markings on the planet Jupiter were communicated to the Royal Astronomical Society at the November meeting by Mr. Barnard. A careful study of numerous details observed during a period of twelve years has led to the conclusion that the red colour of any of the markings is an indication of their age; or in other words, when a spot or marking (other than the white spots first appears it is dark or black, but after some time turns red." Several examples are given of this transition, and the great red spot seems to be no exception to the rule. Measurements of transits of the broken chain of small black spots just north of the north equatorial belt, discovered by Mr. Barnard during the present year, show that the spots have a very large relative motion, for they complete a revolution around Jupiter in about thirty-seven days. The oblong dusky spot discovered near the great red spot last year is diminishing its longitude by about o ̊54 per day, and so completes a revolution relatively to the latter in about 167 days. This, and other new red markings in the southern hemisphere, seem to have their origin in the region of the great red spot. Their period of rotation is about the same as the round white spots in the same hemisphere, the longitudes of which diminish by about o 6 per day. The observations show that the great red spot is stationary in longitude, and possibly shorter and broader now than in 1880. Further observations of the first satellite have been made in order to throw light upon the apparent duplicity of this body in transit, distinctly seen by Mr. Barnard on September 8, 1890. It is noted :-" The phenomena seen on these occasions would rather discourage the idea of actual duplicity. At these times the satellite has appeared egg-shaped when in relief on the dark belt. . . . I am confident that this particular phase, and perhaps also that of apparent duplicity, is explained by a bright belt on the satellite or by darkness of the polar regions, which is the same thing." Mr. Stanley Williams has suggested that the phenomenon observed on September 8, 1890, may have been due to the satellite having been seen in transit as a dark spot close to a dark spot on the surface of Jupiter which transited at the same time.

SPECTRA OF THE SUN AND METALS.-Some extremely fine comparative photographic spark-spectra of the sun and metallic elements were exhibited by Mr. F. McClean at the meeting referred to in the above note. The spectra extend, in six sections, from a 3800 to A 5750—that is, from about L of the solar spectrum to near D. They are divided into two seriesone containing spectra of the sun, iron, platinum, iridium, osmium, palladium, rhodium, ruthenium, gold, and silver; the other containing spectra of the sun, iron, manganese, cobalt, nickel, chromium, aluminium, and copper. The scale of wavelength adopted is that of Ångström's map. Since the spark was taken in air all the spectra have air-lines running through them. The purest materials obtainable were used as electrodes : nevertheless a large number of lines due to foreign substances appear on the photographs. The commonest impurity is calcium, its lines being present in very nearly all the spectra. No attempt has been made to eliminate the lines having their origin in such impurities; hence, as Mr. McClean remarks, it is impossible to obtain any complete results from these two series of photographs alone. Photographs of the spectra of all the common oxidizable metals, and particularly of calcium, barium, magnesium, and titanium are first required."

Astronomische Nachrichten, No. 3069, contains a paper by Prof. Pickering on the distribution of energy in stellar spectaa. Since stellar magnitudes obtained by various processes, such as photography, eye-observations, &c., cannot be co upared when the light of stars is of different colours, the method he proposes is to adopt a single wave-length in the spectrum to which all intensities should be referred, a curve or series of numbers

being necessary to give a measure of the rays of each different wave-length. For rays of different wave-lengths he says: "The intensities may be determined by comparing the densities of different portions of the photographic spectrum." The line fixed upon was that of the hydrogen line G, "as it is near the centre of the photographic spectrum." The photographs he employed were those forming part of the Henry Draper Memorial, all taken under similar conditions, and in each one separately twenty points were taken and compared by comparison with a standard photographic wedge. Each of the measures thus obtained was converted into logarithmic intervals, and the measure, corresponding with that of the hydrogen line G of wave-length 434, was deducted. By subtracting the values of the logarithm of the energy of the solar light, the remainder showed the excess or deficit of energy of the star as compared with that of the sun, eliminating the various sources of error enumerated above." In the table below we give the results for three stars as obtained by Prof. Pickering :

The values in the second column representing the logarithm of the energy of the solar light, while those in the last one represent the energy of sunlight itself. Thus in the case of a Orionis, the energy for the wave-length 390 is represented by- o'57, sunlight being 0:55. The absolute energy is found "by adding the tabular number to that given for sunlight in the second column," so that we have o 26 0'57 = −0·83, corresponding to a ratio of 015. Thus the energy of the light of a Orionis of wave-length 390 is only about one-seventh of that of wave-length 434.

In this number, also. Mr. Truman Saffard contributes a paper on the observation of North Polar stars in the vertical of Polaris. After mentioning the difficulty of observing polars in the daytime, of connecting other polars with double transits of Polaris, and of the independence that now exists in the various Polar catalogues, he describes a method which tends to eliminate many of these deficiencies. It consists in adjusting a transit so that Polaris will be near its centre wire at eastern elongation, which takes place about 19h. 23m. sidereal time, and the two stars Camelopardalis 25 H and Schwerd 1172 (Carrington 2965), which pass the same vertical within about half an hour of this time, the latter above Pole, earlier than the Pole-star reaches

For the preliminary experiments which are to be described it was thought desirable to use the 12-inch equatorial. Accordingly, acap, provided with two adjustable slits, was fitted over the objective, and provided with a rod by means of which the distance between the slits could be altered gradually and at will by the observer, while the distance was measured on a millimetre scale attached to the sliding jaws. This arrangement, which was constructed under the supervision of Mr. F. L. O. Wadsworth, of Clark University, is shown in the accompanying diagram, Fig. 3.

Fig 3

the disappearance could still be sharply marked. Indeed the concordance of the observations made under different circumstances on different nights was even closer than was expected. With a larger telescope both the brightness of the fringes and their distance apart will be increased, and it may be confidently predicted that the accuracy will then be even greater.

The values given in the second column, Engelmann," are probably more reliable than the succeeding ones, but it is well worth noting that the results obtained by interference agree with the others quite as well as these agree with each other.

It should also be noted that the distance between the slits was about four inches. It may therefore be stated that for such measurements as have just been described, a telescope sufficiently large to admit a separation of four inches-say a six-inchsuitably provided with adjustable slits is fully equal to the largest telescopes now used without them.

It is hoped that within a few months the 36-inch equatorial will be supplied with a similar apparatus and observations begun for the definite measurement of the satellites of Jupiter and Saturn and such of the asteroids as may come within the range of the instrument.

In concluding, I wish to take this opportunity of expressing my appreciation of the courtesy of Director Holden in placing all the facilities of the Observatory at my disposal, and of the hearty co-operation of all the astronomers of the Observatory, especially the valuable assistance of Prof. W. W. Campbell in making the observations. A. A. MICHELSON.

Mount Hamilton.

THE SAMOAN CYCLONE OF MARCH 16, 1889. THE Samoan hurricane of March 16, 1889, is one of those

historic storms that have been rendered for ever memorable by the episodes of disaster and gallantry that attended them; by the escape of H.M.S. Calliope, which forced her way out of Apia harbour in the teeth of the hurricane, amid the cheers of the brave American sailors, who, themselves face to face with imminent death, forgot for a moment their own dire peril in their admiration of the daring and successful act of seamanship that rescued their more fortunate brothers. Mr. Everard Hayden, of the U.S. Hydrographic Office, has lately issued a preliminary Report on this storm, which, despite the regrettable meagreness of the data at his command, has, nevertheless, a certain scientific interest, inasmuch as less is known of the

seas.

The Apia storm, like the cyclones of the South Indian Ocean, was evidently formed on the northern limits of the south-east trades, and was one of a series that were generated in this region in March 1889. The first of these, in Mr. Hayden's opinion, appears to have originated on the 5th of the month, some 500 miles north-north-east from the Samoan Islands, and to have travelled first in a south-westerly direction, recurving in the latitude of these islands, but at 150 to 200 miles to the west of them, after which it took a south-eastward course between Tonga and Nuie. It seems to have been a storm of great severity, and its passage was felt at Apia on the 6th and 7th, though not with any great intensity. It was succeeded by the cyclone that forms the principal subject of Mr. Hayden's Report. This, he thinks, was formed about March 13, some 300 miles to the north-east of the Samoan Islands, and on the 15th its centre passed either directly over, or a little to the north of, Apia harbour, moving, therefore, on a south-west course. He considers that it then sharply recurved, and that, with greatly increased strength, it passed a second time over Apia on the 16th, the day of the great naval disaster. The chief facts which led Mr. Hayden to this conclusion are those observed at Apia itself, for no positive evidence is forthcoming from the supposed birthplace of the storm, and only one ship reports the state of the weather any where to the north of Samoa. The peculiar feature of the Apia observations is, that the barometer fell steadily from the 12th to the afternoon of the 15th (about o'7 inch), then rose (about 0.25 inch) during the latter part of that day, and then again fell on the 16th to a reading slightly lower than that of the previous day. On the 15th, squalls of moderate force (wind southerly, force 2 to 6) were experienced, and in the after part of the day, as the barometer rose, the direction changed from south to north and east. There had been no heavy sea, and it was thought that the gale was over. At midnight, however, the barometer began

falling again, the wind had increased, and the sea was high. The barometer continued falling, and the gale rapidly developed its full strength. From early morning of the 16th, for nearly twenty-four hours, it blew a hurricane, and the catastrophes commenced with the loss of the Eber.

Any attempted interpretation of facts so meagre must necessarily be in a great measure speculative. We have given that of Mr. Hayden, and others have been suggested. One, that of Lieutenant Witzel, is to the effect that the storm of the 16th was distinct from that of the previous day, and originated over Savaii (the island to the west of Upolu, in which is the harbour of Apia). Another, by Mr. Dutton, is that the storm of the 15th, after approaching the Samoan Islands on a south-west track, recurved to west and north-west, and during the following night again recurved sharply, describing a loop north of Savaii, and then returning towards Upolu, whence it moved southwards and south eastwards. Our own interpretation is somewhat different from any of these, and seems to be more in accordance with the habits of tropical cyclones, the movements of which are by no means so erratic as that implied by Mr. Dutton's hypothesis, while it does not involve the extremely and, we think, improbably sharp recurvature suggested by Mr. Hayden, nor the equally improbable generation of a second vortex only one day in the rear of the storm of the 15th, as supposed by Lieutenant Witzel. None of these explanations seem to take account of the circumstances that attend the formation of tropical cyclones, which, as we have elsewhere pointed out, differ in many respects from the storms of the temperate zone.

It is evident from [the considerable and steady fall of the barometer at Apia from March 12 to 15, that the Samoan Islands lay within the area of disturbance in which the storm was generated, and that the formation of the vortex was simply the concentration of this disturbance, which probably took place nearer to Apia than is supposed by Mr. Hayden, but still at such a distance that the first effect of the concentration-viz. a slight rise of the barometer in the area immediately around, and especially on the polar side-was felt at the Samoan Islands. If, then, as seems probable, the vortex was not formed until the afternoon of the 15th, this, in conjunction with the ordinary diurnal rise between 4 and 10 p.m., would account for the slight rise observed at Apia on the latter part of that day, and only the second fall to a minimum on the 16th was due to the actual passage of the cyclone. From the severity of the storm, as felt at Apia harbour, it is clear that Upolu must have been traversed by at least a portion of the inner vortex, but it could hardly have been very close to the centre, seeing that the barometer never fell to 29 inches; and therefore the long duration of the hurricane (24 hours) can only be explained by the very slow rate at which the storm was then travelling. This slow rate of progression strengthens the probability that it had not proceeded far from its birthplace, since, as a rule, tropical cyclones move forward slowly at first, and only gradually acquire greater speed of translation. It also strengthens the inference that it had originated not very far to the north or north-east of Upolu. This explanation, as already remarked, can only be regarded as tentative, but it seems at least worthy of consideration by those who may have fuller data at hand. H. F. B.

UNIVERSITY AND EDUCATIONAL
INTELLIGENCE.

CAMBRIDGE.-The Sheep-hanks Astronomical Exibition has been awarded to P. H. Cowell, Scholar of Trinity College.

A memorial signed by 107 members of the Senate is published by the Vice-Chancellor : it expresses the opinion that "the whole question of degrees in science should be considered by the University." Among the signatures are some of those who took the Greek as well as some who took the anti-Greek side in the recent controversy.

In view of the fall in the aggregate of the Colleges the Council of the Senate propose to obtain powers for deferring the next increment of the College contribution to the University from 1893 to 1895, and the following increment (from £25,000 to £30,000) for seven years further-namely, to 190j.

Sir George Gabriel Stokes and Prof. Macalister, M. D., are among the delegates appointed to represent the University at the Dublin Tercentenary Festival next year.

Mr. E. W. Hobson, of Christ's College, is approved as Deputy

for the Lowndean Professor of Astronomy for the Lent and Easter Terms.

We regret to hear that Prof. Adanis's health does not yet allow him to resume his duties.

SOCIETIES AND ACADEMIES.
LONDON.

Royal Society, November 19.-"The Thermal Emissivity of Thin Wires in Air." By W. E. Ayrton, F.R.S., and H. Kilgour.

In 1884 it was observed experimentally that whereas the electric current required to maintain a thick wire of given material, under given conditions, at a given temperature was approximately proportional to the diameter of the wire raised to the power three halves, the current was more nearly proportional to the first power of the diameter if the wire were thin. When this difference in the behaviour of a thick and thin wire was first noticed, it was regarded as being quite unexpected. But, as pointed out by one of us in the course of a discussion at a meeting of the Royal Society, the unexpected character of the result was due to people having assumed that the loss of heat from radiation and convection per square centimetre of surface per 1° excess temperature was a constant, and independent of the size and shape of the cooling body.

The very valuable investigations that have been made on emissivity by Mr. Macfarlane, Prof. Tait, Mr. Crookes, Mr. J. T. Bottomley, and by Mr. Schleiermacher, had for their object the determination of the variation of the emissivity with changes of the surface and with change in the density of the gas surrounding the cooling body, but it was not part of these investigations to determine the change in the emissivity that is produced by change in the shape and size of the cooling body. Indeed, so little has been the attention devoted to the very large change that can be brought about in the value of the emissivity by simply changing the dimensions of the cooling body, that in Prof. Everett's very valuable book of "Units and Physical Constants" the absolute results obtained by Mr. Macfarlane are given as the "results of experiments on the loss of heat from blackened and polished copper in air at atmospheric pressure," and no reference is made either to the shape or to the size of the cooling body.

[November 19, 1891.-Since this paper was sent in to the Royal Society a new edition of this book has appeared, and, in consequence of a suggestion made to Prof. Everett, the word "balls has been added after the word " copper in this new edition, as well as the following paragraph Influence of Size.-According to Prof. Ayrton, who quotes a table in Box on Heat,' the coefficient of emission increases as the size of the emitting body diminishes, and for a blackened sphere of radius r centims. may be stated

:

The value of r in Macfarlane's experiments was 2."]

The laws which govern the los of heat from very thin cylindrical conductors have not only considerable scientific interest in showing how the shape of a body affects the convection currents, but they are of especial importance to the electrical engineer in connection with glow lamps, hot-wire voltmeters, fuses, &c. We therefore thought it desirable to ascertain the way in which the law of cooling for thick wires, which involved the diameter raised to the power three halves, passed into the law for the cooling of thin wires, involving only the first power of the diameter. For this object, the investigation described in the paper was commenced at the beginning of 1888, and the emissivity was measured of nine platinum wires, having the diameters of 12, 2'0, 29, 40, 60, 81, 93, 11'1, and 14 mils, or thousandths of an inch.

Suspecting that some of the published results on the currents required to fuse wires had been much influenced by the cooling action of the blocks to which the ends of the wires were attached, we started by making a calculation of the length necessary to give to our wires, so that the loss of heat by conduction should not introduce any important error into the determination of the emissivity. To do this it was necessary to calculate the distribution of temperature along a wire through which a steady current was flowing, and from which heat was lost by radiation,