Imágenes de páginas
PDF
EPUB
[ocr errors]
[ocr errors]
[ocr errors]

intepreted all of them. Three of his translations, which were published in the Times of Saturday last, are invocations to the sun and water gods, and, apparently, to the divinity of the moon. Capt. Conder says that not only the words, but the grammar of the inscriptions, can be shown to belong to a wellknown tongue. What this tongue is, we are not to learn for some time.

WE regret to announce the death of Dr. Grothe, Professor at the Polytechnical School at Delft, author of "Mechanical Technology," and an excellent monograph on iron. He was born in Westphalia in 1806, and died on February 10 last.

PROF. HAECKEL, of Jena, has just started on a journey to the East, which will be of some months' duration. He will visit the coast of Asia Minor to continue his investigations of lower marine animals.

LIEUT. QUEDENFELDT has just returned from Morocco to Berlin, bringing with him some valuable collections: an ethnological one, which he has presented to the Anthropological Society, a collection of insects, and a large collection of the implements, tools, and instruments of torture of the Hamadjas tribe.

[ocr errors]
[ocr errors]

MESSRS. G. PHILIP AND SON have in the press a revised and enlarged edition of "The Geology of England and Wales," by Horace B. Woodward, F.G.S., of the Geological Survey of England. They will also have ready shortly Philips' Plani sphere of the Stars visible from the Countries situated about 35 south of the Equator" (uniform with 'Philips' Planisphere for England"); "Rustic Walking Routes within the Twelve-mile Radius from Charing Cross," containing a fieldpath map of the district, with geographical description, charts, and directions, by W. R. Evans; and "Philips' Handy Volume Atlas of the World," consisting of sixty-four plates, containing upwards of one hundred maps, printed in colours, with statistical notes on each map.

MESSRS. WHITTAKER AND CO. will publish shortly a second and much enlarged edition of "Magnets and Dynamo-Electric Machines," being the first volume of their "Specialist's Series." For the new edition some revisions in the text have been made, and a preface and a chapter on the latest types of generators have been written by Mr. W. B. Esson.

A FRENCH translation has been published of Cæsar Lumbroso's "Uomo Delinquanti," with a fine series of figures to illustrate the learned author's lectures concerning the anthropological features of the professional criminal.

ADMIRAL TEISSERENC DE BORT has just published a map, showing the distribution of fog on the various parts of the earth. It is based upon observations made at 1600 land stations, and 112,000 marine ones.

IN a Report just issued, Mr. S. W. North, Medical Officer of Health, calls attention to the prevalence of typhoid fever in York during the year 1886. For many years York has been liable to outbreaks of this disease, and the fact will not surprise anyone who reads Mr. North's account of the sanitary conditions of the city.

IN a paper entitled "Ueber die Allgemeine Beugungsfigur in Fernröhren" (Mémoires de l'Académie Impériale des Sciences de St. Pétersbourg, viie. série, tome xxxiv., No. 5), Hermann Struve remarks that the old problem of the diffraction of light through a circular aperture, the source being in the axis, has been considered by Airy and others, who have given approximate solutions in special cases; but the general solution has only been made feasible by the discovery of Bessel's functions. He accordingly proceeds to develop it by the straightforward methods with which readers of modern analysis are familiar;

showing how his solution accords with those previously given for the axis and for the edge of the geometrical shadow. In this latter case he remarks that the illumination is less than onefourth that which would be obtained by removing the screen. His results are put into a useful numerical form in tables at the end of the paper.

THE last number of the Bulletin of the Belgian Natural History Museum contains a summary of ornithological observations made at various stations throughout Belgium during the year 1885. This is quite a novel feature, which, if carried out systematically, promises excellent results, especially as regards the many obscure questions connected with the migrations of birds of passage. The chief stations are Brussels, Hasselt, Carlsburg, and the Ostend and other lighthouses along the coast. The names of the naturalists who undertake to send in reports are given in all cases. These reports contain the name of the bird in three languages-Latin, French, and Flemish or Walloon according to the locality-followed by the dates of arrival and departure, and any other remarks tending to throw light on the habits and movements of the bird. Thus, under Ciconia alba, Bechst., Cicogne blanche, Ooievaar (white stork), we have, from the Nieuport Lighthouse: "Seven seen, June 18, flying westwards; rare on this coast, where they never nest.-Signed, A. Vermorke." The present summary contains 171 such entries, the value of which, when made by competent observers from year to year, ornithologists will not fail to appreciate.

THE latest advices from Honolulu report that the volcano of Mauna Loa is again in eruption, and that all the craters in the vicinity have become active.

IN the December nu nber of the Mineralogical Magazine, Prof. Macadam gives the analysis of a sample of talc used in paper-making. This mineral is obtained from New Jersey. It is very largely employed for paper-making in place of China clay (kaolin), and gives, amongst other advantages, a much more pure effluent, fully 90 per cent. being retained in the paper. From its fibrous nature it appears to attach itself to the smaller paper particles, and retain these also. The very high and beautifully smooth glaze of the American papers is largely due to the use of this substance.

IN the Mittheilungen of the Zürich Antiquarian Society (Band xxii. Heft 1) will be found a detailed account of the recently-discovered lake-dwelling at Wallishafen, on the Lake of Zürich. The articles found were mainly bronze, but underneath the existing remains appear to be the charred fragments of an earlier dwelling, the remains of which clearly belong to the Stone Age.

A LARGE canoe, belonging to prehistoric times, was lately dragged from the bottom of the River Cher, near Vierzon, and is now in the Museum of the Society of Antiquaries at Bourges. A part of it had been visible for many years at low water, but no one understood what it was until it happened to be seen by M. Beauchard, who at once perceived its real character. When it was brought to land, fragments which had been torn or cut off by peasants were recovered and pieced together. The canoe is in the form of a trough, and is said to have a general resemblance to the ancient boat found some time ago at Brigg, in Lincolnshire. The present specimen has the special characteristic of being closed at both ends by pieces of wood fixed in vertical grooves. This device seems to have been adopted in consequence of the boat having been injured by some accident. M. GUILMETH, the French traveller, while on a journey in Australia, discovered some bee-hives in a gigantic eucalyptustree, of 120 metres in height. The honey was strongly scented with the perfume of the flowers of the tree. Prof. Thomas Karaman has examined it, and believes it to have beneficial medicinal properties.

LIKE the authorities of the National Museum, Washington, the Curators of the Museum of the Academy of Natural Sciences, Philadelphia, complain that they have not nearly room enough for the display of the collections intrusted to their charge. "It is well within the truth," they state in their Report for 1886, "to say that the existing collections, if properly displayed, would completely fill a building of twice the dimensions of the present one. The large and very valuable collections of the Pennsylvania Geological Survey, contained in upwards of 200 cases, still remain in the cellar, boxed, for want of exhibition space. The types of the greater number of the fossil plants described by Lesquereux in his 'Coal Flora of the United States,' probably one of the most valuable collections of fossil plants in the world, have been added to this collection during the year, but, for similar reasons, still remain boxed. The report of the Professor of Ethnology and Archæology indicates that accessions to this department of the Academy's Museum could readily be had were proper exhibition space provided, but that under present conditions the same is impossible. In view of these facts the necessity for an extension to the Academy's building cannot be too strongly insisted upon." The Curators also urge that a fund should be raised for zoogeographical exploration. The interest derived from 50,000 dollars would, they think, fairly equip an annual expedition to any of the largely-unexplored regions lying about the dominions of the United States, such as Mexico, Central America, the Bahamas, and Labrador.

MR. ARTHUR J. BETHELL has reprinted, with additions and corrections, three articles which lately appeared in the Field, on a ride to the Falls of Zambesi. He has added a number of notes which may be of considerable service to men who think of spending some time in hunting in South Africa.

IT was decided some time ago that a number of the Crown diamonds of France should be sold. Others were put aside for the collections of the Paris School of Mines and Museum of Natural History; and these gems were recently given to the delegates appointed by the two Schools. The Regent diamond, a very fine one, will be kept in the Louvre Gallery.

THE additions to the Zoological Society's Gardens during the past week include a Bonnet Monkey (Macacus sinicus), a Macaque Monkey (Macacus cynomolgus) from India, presented by Miss E. James; a Three-striped Paradoxure (Paradoxurus trivirgatus) from India, presented by Mr. Gerald Callinder; a Common Squirrel (Sciurus vulgaris), British, presented by Miss May Honrott; a Scop's Owl (Scops qui), captured at sea near Aden, presented by Mr. W. M. Holland; a White-fronted Heron (Ardea novæ-hollandiæ) from Australia, presented by Mr. J. B. Dyas; a Stanley Parrakeet (Platycercus icterotis) from West Australia, a Burmeister's Cariama (Chunga burmeisteri) from South-East Brazil, a Black Sternothere (Sternotherus niger) from West Africa, received in exchange; two Smews (Mergus albellus 89), European, purchased.

[merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small]
[merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][ocr errors][ocr errors][merged small]
[ocr errors]

A METHOD FOR THE DETERMINATION OF THE CONSTAT OF ABERRATION.-M. Loewy, in reply to M. Houzeau's car to be considered the originator of the method for determin tion of aberration by measurement of the relative p tions of two stars situated in distant parts of the (NATURE, vol. xxxv. p. 377) points out, in the Com rendus, tome civ. No. 7, that the invention of a new meth for the determination of the constant of aberration does consist in a general indication of the effect of aberration certain observation or combination of observations, but furnishing definite rules the following out of which will lead to results of the accuracy demanded by the exigencies of moles science. M. Loewy maintains that M. Houzeau's researches (2 the subject come under the former category, whilst his own entitled to be ranked under the latter.

The same number of the Comptes rendus contains a note M. Trépied pointing out how photography can be appl the purpose of practically carrying out M. Lrewy's methof.

L

THE HARVARD COLLEGE OBSERVATORY.-From Prot Pickering's Report, presented on December 7, 1886, we lear that during the past year the east equatorial has been wel the photometric observation of the eclipses of Jupiter's wires upon the system adopted in 1878. The total numero eclipses thus observed is 358, of which 39 have occaneden the end of October 1885. With the same equatecal d observation of comparison stars for variables with the welf photometer has been continued, and has formed the prite work of the instrument. The "new" stars in Orion and Andro meda, and comets, have also been observed with the east fe torial throughout the year. The reduction and publication work already done with the meridian-circle is at present, 12 Prof. Pickering's opinion, more desirable than the prosecute of new series of observations. This department of the b vatory has sustained a heavy loss in the resignation of Prd, Rogers, who has devoted many years to laborious astronomica work at Harvard College. During the year ending November 1. 1886, 209 series of measures have been made with the meridiza photometer. The total number of separate photometric compan sons is 59,800. The instrument continues to give entire satula magnitude or brighter. The average deviation of 100 circumpolar tion as a means of measuring the brightness of stars of the ninth stars used as standards, which, with the smaller instrument of the same kind employed in the Harvard photometry, was 0 of a magnitude, has been reduced to o'12 with the present instru ment; whilst the average deviation of stars from the fifth to the ninth magnitude but little exceeds o't of a magnitude And a comparison between the results obtained by Dr. Linde mann, at Pulkowa, with a Zöllner photometer, and at Harvard College, with the meridian-photometer, shows that the averag deviation of a measurement of the difference in brightness between two stars observed at both places does not exceed o't of a magnitude. For an account of the interesting and import

ant researches in stellar photography which have recently been carried out at the Harvard College Observatory, see NATURE,

vol. xxxv. p. 37.

This is

NEW MINOR PLANET.-A new minor planet, No. 265, was discovered on February 27, by Herr Palisa, at Vienna. the tifty-eighth that Herr Palisa has discovered.

ASTRONOMICAL PHENOMENA FOR THE
WEEK 1887 MARCH 6-12

(FOR the reckoning of time the civil day, commencing at
Greenwich mean midnight, counting the hours on to 24,
is here employed.)

At Greenwich on March 6

Sun rises, 6h. 37m. ; souths, 12h. 11m. 28 1s. ; sets, 17h. 46m.; decl. on meridian, 5° 40' S.: Sidereal Time at Sunset, 4h. 43m.

Moon (Full on March 9) rises, 13h. 39m.; souths, 21h. 29m. ; sets, 5h. 10m.*; decl. on meridian, 17° 4′ N.

[merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors]

Sets
h. m.

19 36

19 50 18 48 823

4 20*

Decl. on meridian

[ocr errors]

3 22 N. 2 16 N.

1 58 S.

12

2 S. 22 28 N. Indicates that the rising is that of the preceding evening and the setting that of the following morning.

Occultations of Stars by the Moon (visible at Greenwich)

[merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][ocr errors][ocr errors][merged small][merged small][ocr errors][ocr errors][merged small][ocr errors][merged small][merged small][merged small]

Corresponding angles from vertex to right for inverted image

...

131 289

67 337 68 185 61 III

22 53 near approach 332

3 7

340

145 210 4 22 near approach 186

Mercury stationary.

20 Jupiter in conjunction with and 3° 34′ south

***

of the Moon.

[merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][ocr errors][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][ocr errors][merged small][ocr errors][merged small][ocr errors][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][ocr errors][ocr errors][ocr errors][merged small][merged small][ocr errors][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][ocr errors][ocr errors][merged small][merged small][merged small][ocr errors][merged small][ocr errors][merged small][merged small]

ing under the excitement of the induction discharge in vacuo, I have found very great differences in the duration of the residual glow. Some earths continue to phosphoresce for an hour or more after the current is turned off, while others cease to give out the light the moment the current stops. Having succeeded in splitting up yttria into several simpler forms of matter differing in basic power (Roy. Soc. Proc. vol. xl. pp. 502-509, June 10, 1886), and always seeking for further evidence of the separate identity of these bodies, I noticed occasionally that the residual glow was of a somewhat different colour to that it exhibited while the current was passing, and also that the spectrum of this residual glow seemed to show, as far as the faint light enabled me to make out, that some of the lines were missing. This pointed to another difference between the yttrium components, and with a view to examine the question more closely I devised an instrument similar to Becquerel's phosphoroscope, but acting electrically instead of by means of direct light.

The instrument, shown in Fig. 1, A and B, consists of an opaque disk, a bc, 20 inches in diameter, and pierced with twelve openings near the edge as shown. By means of a multiplying wheel, d, and band, ef, the disk can be set in rapid rotation. At each revolution a stationary object behind one of the A apertures is alternately exposed and hidden twelve times. commutator, g (shown enlarged at Fig. 1, B), forms part of the axis of the disk. The commutator is formed of a hollow cylinder of brass round a solid wooden cylinder. The brass is cut into two halves by a saw cut running diagonally to and fro round it, so as to form on each half of the cylinder twelve deeply cut teeth interlocking, and insulated from those on the opposing half cylinder by an air space about 2 mm. across. Only one half, hhh, of the cylinder is used, the other, i ii, being idle; it might have been cut away altogether were it not for some little use that it is in saving the rubbing-spring, j, from too great friction when passing rapidly over the serrated edge. To a block beneath the commutator are attached two springs, one, k, rub bing permanently against the continuous base of the serrated hemicylinder h h, and the other, j, rubbing over the points of the teeth of h h. By connecting these springs with the wires from a battery it will be seen that rotation of the commutator produces alternate makes and breaks in the current. The spring, j, rubbing against the teeth is made with a little adjustment sideways, so that it can be said to touch the points of the teeth only, when the breaks will be much longer than the makes, or it can be set to rub near the base of the teeth, when the current will remain on for a much longer time and the intervals of no current will be very short. By means of a screw, /!, attached to the spring, any desired ratio between the makes and the breaks can be obtained. The intermittent primary current is then carried to an induction coil, m, the secondary current from which passes through the vacuum tube, n, containWhen the commutator, the ing the earth under examination. coil-break, and the position of the vacuum tube are in proper adjustment, no light is seen when looked at from the front if the wheel is turned slowly (supposing a substance like yttria is being examined), as the current does not begin till the tube is obscured by an intercepting segment, and it ends before the earth comes into view. When, however, the wheel is turned more quickly, the residual phosphorescence lasts long enough to bridge over the brief interval of time elapsing between the cessation of the spark and the entry of the earth into the field of view, and the yttria is seen to glow with a faint light, which becomes brighter as the speed of the wheel increases.

To count the revolutions, a projecting stud, o, is fastened to the rotating axis, and a piece of quill, p, is attached to the fixed support, so that at every revolution a click is produced. With a chronograph watch it is easy in this way to tell the time, to the tenth of a second, occupied in ten revolutions of the wheel. Under ordinary circumstances it is almost impossible to detect any phosphorescence in an earth until the vacuum is so high that the line spectrum of the residual gas begins to get faint; otherwise the feeble glow of the phosphorescence is drowned by the greater brightness of the glowing gas. In this phosphoroscope, however, the light of glowing gas does not last an appreciable time, whilst that from the phosphorescent earth endures long enough for it to be caught in the instrument. By this means, therefore, I have been able to see the phosphorescence of yttria, for example, when the barometer gauge was 5 or 6 mm. below the barometer.

When the earth under examination in the phosphoroscope is yttria free from samaria, and the residual emitted light is ex

[merged small][merged small][graphic][subsumed][ocr errors][merged small][subsumed][subsumed][subsumed][subsumed][ocr errors][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][graphic][merged small][merged small][merged small][ocr errors][merged small][ocr errors][merged small][merged small][merged small][merged small]

At o'000875 sec. interval the highest speed the instrument

could be revolved with accuracy, the whole of the lines usually seen in the yttria spectrum could be seen of nearly their usual brightness.

I have already recorded (Phil. Trans., 1883, Part III. pp. 914-16), that phosphate of yttria, when phosphoresced in vacuo, gives the green lines very strongly whilst the citron band is hazy and faint. The same tube of yttric phosphate was now examined in the phosphoroscope. The green lines of GB soon showed themselves on setting the wheel into rapid rotation, but I was unable to detect the citron band of Gd even at a very high speed.

The effect of calcium on the phosphorescence of yttria and samaria has been frequently referred to in my previous papers. It may save time if I summarise the results here About I per

[blocks in formation]

Per cent.

[merged small][merged small][subsumed][ocr errors][ocr errors][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small]

It

30

70

25

75

cent. of lime added to a badly phosphorescing body containing yttrium or samarium always causes it to phosphoresce well. diminishes the sharpness of the citron line of G8 but increases in brightness. It also renders the deep blue line of Ga extremely bright. The green lines of GB are diminished in brightness. Lime also brings out the phosphorescence of sama ium, although by itself, or in the presence of a small quantity of yttrium, samarium scarcely phosphoresces at all.

In the phosphoroscope the action of lime on yttrium is seen to entirely alter the order of visibility of the constituents of yttrium. In a mixture of equal parts yttrium and calcium, the citron Gỗ line is the first to be seen, then comes the Ga blue line, then the GB green line, and finally the Gŋ red line. This may, I think, be explained somewhat as follows:-Calcium sulphate has a long residual phosphorescence, whilst yttrium sulphate has a comparatively short residual phosphorescence. Now with yttrium, although the green phosphorescence of G8 lasts longest, it does not last nearly so long as that of calcium sulphate. The long residual vibrations of the calcium compound induce, in a mixture of calcium and yttrium, phosphorescence in those yttric molecules (G8) whose vibrations it can assist, in advance of those (GB) to which it is antagonistic; the line of G8 therefore appears earlier in the phosphoroscope than that of GB, although were calcium not present the line of GB would appear first.

Experiments were now tried with different mixtures of yttria and lime as ignited sulphates, to see where the special influence of lime on Gỗ ceased.

[blocks in formation]
[merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small]

The follow

In the phosphoroscope the GB line appears earliest, but the blue Ga line is the next to be seen, whilst the red line of Gn is the latest in appearing. As the percentage of yttrium increases the blue line more and more overtakes the red and increases in brightness.

Spectrum similar to the above. As the percentage of yttrium increases the spectrum grows brighter. In the phosphoroscope the earliest line to appear is the GB green, then the Gn red, and next closely following it the Ga blue.

In the radiant-matter tube all these mixtures give similar spectra. The GB green is a little brighter and the Gô citron is a little fainter than in the corresponding mixtures of yttrium and calcium, but the whole of the yttrium lines are seen. In the phos. phoroscope the G8 green is the first to appear, then the Gn red. The G8 citron

is not visible at any speed. Red line of Gn is much brighter; G is very faint, and the green of GB is stronger. In the phosphoroscope the order of ap pearance is, first the line of GB, then the red line of Gn.

Phosphoresces with difficulty, of a light blue colour, but turns brick-red in the focus of the pole. Spectrum very faint. Order of appearance to phosphoroscope, -GB first, the others too faint to be seen.

The next experiments were tried with strontium, to see what modification the addition of this body to yttrium would produce. The following mixtures of ignited sulphates were experimented with :

Yttrium Stron:ium

[merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small]

Order of appearance in the phosphoroscope. -GB, Ga, Gỗ, and Gŋ. The citron line of Gd is only to be seen at a high speed, and is then very faint. Order of appearance in the phosphoroscope. -Ga, GB, and Gỗ (citron and blue) together, and lastly Gn (red). At a very high speed the green lines of GB become far more luminous than any other line. Order of appearance.-Go and Ga together, then GB, and lastly Gn.

The

Order of appearance.-G8 and Ga simultaneously, then GB, and lastly Gn. residual phosphorescence lasts for 30 seconds after the current stops. light of this residual glow is entirely that of GỖ. The line of GB comes into view at an interval of 0.0015 second. At 000175 second the line of Gŋ is just visible.

[merged small][merged small][merged small][merged small][merged small][ocr errors][merged small]

The

40

[blocks in formation]
[merged small][merged small][merged small][subsumed][subsumed][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small]

In the

A very good yttrium spectrum. phosphoroscope the order of appearance is, first the green of GB, then the Ga. blue, lastly the Gn red. No Gỗ citron line could be seen.

In the phosphoroscope the green of GB is very prominent at a low speed, standing. out sharply against a black background. With a higher velocity the Ga and Gn lines come into view.

The ordinary spectrum of this and the neighbouring mixtures is very rich in the citron line of G8, but I entirely fail to see a trace of this line in the phosphoroscope at any speed. The line of GB is the first to come, then the blue line of Ga. At about this point a change comes over the appearance in the phosphoroscope. The blue line of Ga is now the earliest to appear, and it is followed by the Gŋ red and GB green. No G8 line is seen. These mixtures are very similar to each other in the phosphoroscope. The line of Ga comes first, next the Gŋ line, then GB line. No Gỗ citron line has been seen in any of these mixtures.

In a paper read before the Royal Society, June 18, 1885. (Phil. Trans., 1885, Part II., p. 716), I describe the phos

« AnteriorContinuar »