filling in from Professor Phillips' map, our astronomical readers will be enabled to obtain views of the planet at successive intervals of two (Martial) hours. Such views would suffice for comparison with any telescopic views taken near the time of southing, or with views taken at any hour, if due regard be paid to the varying slope of the planet's axis. Towards the end of February the planet (now become much smaller) will appear perceptibly gibbous; his maximum stage of gibbosity, attained early in April, and his apparent disc at that time are exhibited in Fig. 2.

Owing, apparently, to a change of authorities, the apparent diameter assigned to the planet in the 'Nautical Almanac' is larger for January 10, 1867, than for December 1st, 1864. Observers, however, must not expect to find the planet larger; in fact, he will be more than 9,000,000 miles farther from the earth on January 10th, than when in opposition in 1864.

Two more minor planets, the 90th and 91st, have been discovered: the first by Dr. Luther, of Bilk, near Düsseldorf, on October 1st; the second at the Marseilles observatory.

On the 6th of March there will be an annular eclipse of the sun, visible throughout England as a partial eclipse. It will begin at Greenwich at 8h. 17m. A.M., and reach its greatest phase at 9h. 32m. A.M., and end at 10h. 52m. A.M. About seven-tenths of the sun's diameter will be obscured at the time of the greatest phase.

We call the special attention of our readers to the obscuration. of the Lunar Crater Linné (on the Mare Serenitatis) observed by Herr Schmidt at Athens. The epoch at which the crater again becomes visible should be carefully noted. This is the same crater that Schröter saw transformed into a dark spot on November 5th, 1788.

PROCEEDINGS OF THE ROYAL ASTRONOMICAL SOCIETY.

Professor Kaiser, of Leyden, in a letter to the AstronomerRoyal, discusses the qualities of the latter's double image micrometer. He expresses a favourable opinion on the instrument, but in one respect astronomers will be disappointed. It has long been known that measurements effected by the best observers with the wire-micrometer present considerable discrepancies. Now, if it had resulted from Professor Kaiser's experiments that the instrument was in fault in such cases, there would have been a prospect of remedying the evil. It appears, however, that the same observer

* The horizontal line through the centre represents the true path of the planet; at the moment of southing" the slope of the axis will be a few degrees less than in Fig. 1, since the planet's motion in opposition will be carrying him slightly northwards.

using both the wire-micrometer and the double-image micrometer in delicate measurements, obtains results appreciably coincident; so that, as Professor Kaiser remarks, " the discrepancies are far more to be sought in the observers than in the instruments." Referring specially to double-star_measurements, he remarks further, that they appear "far too inaccurate for the consequences one will

derive from them." The Professor's list of observations serves to exhibit the close approach to coincidence attained by the use of the two instruments, and to afford to observers new estimates of some favourite test-objects.

General Shortrede discusses the effect of the vapour of mercury in depressing the thermometric column. In temperate climates this effect is not often appreciable, and except in very delicate experiments may perhaps be safely disregarded; but in the tropics, or in exceptionally warm weather, the height of the mercurial column is very sensibly depressed from this cause. In India, for instance, General Shortrede found that the true reading, obtained after tilting the barometer so as to condense the vapour, differed from the observed reading before that operation by from 10 to 20-thousandths of an inch, and on one occasion by so much as 023. The tubes were in exceptionally good order, one having been boiled more than twenty times, the vacuum being so perfect that after the tube had been placed some hours in a horizontal position "the mercury, by electrical attraction, would adhere to the top of the tube, and not separate till shaken by tapping," the tube of 32 in. remaining full in this way, at Pana, where the average height is 28 in.!

The subject seems worthy of investigation, since if we would learn the laws regulating the variations of atmospheric pressure, the minutest circumstances affecting the truth of barometric indications must be recognized, so as to be either eliminated or corrected. The Greenwich photographic registrations are evidently liable to be peculiarly affected by a cause of this kind. General Shortrede noticed, indeed, that on one warm day of the past summer the vacuum of the barometer for outside indications (at Greenwich) was studded with minute globules of mercury, derived from the condensation of the mercurial vapour.

Father Secchi sends a drawing of the spectrum of Antares (the Sirius of red stars). Antares attains a sufficient elevation in the latitude of Rome for satisfactory observation with the spectrometer. As might be expected the spectrum (which, by the way, is presented in a reversed position) exhibits a crowding of lines towards the more refrangible (or violet) end, and several spaces clear of lines, or in which lines are more sparsely strewn, towards the red end.

Captain Noble remarks that Jupiter's third satellite reappeared two minutes before the time predicted in the Nautical Almanac.

The error is, of course, due to a misprint; but the circumstance is noteworthy, as showing the confidence with which astronomers are in the habit of accepting a series of predictions crowded together in a thick octavo volume, published three or four years before the predicted events happen. The non-astronomical world are astonished when the few events which admit of general observation happen as predicted; but it is a source of far greater astonishment to the astronomer that a single telescopic phenomenon out of many thousands predicted should occur a few seconds before or after the predicted time.

In the Comptes Rendus of July 30, and August 6, 1866, there is an interesting paper by M. Faye on variable stars. He sums up the results of his examination of recorded phenomena as follows:

"So-called new stars are not really new, their all but sudden apparition being only an exaggeration of the ordinary phenomenon of periodical variables, a phenomenon corresponding (in turn) to simple oscillations, more or less sensible, in the phenomenon of the production and maintenance of the photospheres of all stars. These phenomena, considered as successive when the history of a star is examined in part, characterize the progress of the cooling of the star, and the decline of its solar or photospheric phase. When these phenomena occur thus in an irregularly intermittent manner, with very long and gradually increasing intervals, they are the precursors of the star's extinction, or at any rate of the formation of a first crust more or less consistent. Hence it is that phenomena of this sort take place only in stars already very faint, and never result in the formation of a fine new star."

Our space will not permit us to deal at length with the papers read and discussed at the November meeting of the Astronomical Society. The remarks in which the President claimed for astronomy the credit of recovering the Atlantic Cable are noteworthy. The connection between the price of Atlantic Telegraph shares and the transit-tube at Greenwich, seems at first sight as far-fetched (and is in reality as just), as that traced by a French astronomer between the cotton trade and Jupiter's satellites.

A paper by Mr. Lynn, "On the mass of Jupiter, as deduced by Herr Krüger from observations of Themis," deals with an important subject. The determination by Pound in the 17th century had for a long time been adopted as the true value, though no account remained of the observations made by Pound beyond the mere statement of the numbers in Newton's 'Principia (lib. iii., prop. viii., cor. i.). The mass thus assigned was th of the sun's mass. But about the year 1826, Nicola

1067

calculated a larger value (1053-924) by means of the perturbations

of Juno; Encke from the perturbations of Vesta found the value

1 and from the perturbations of the comet bearing his name,

1050

1054*

Gauss confirmed these results by observations of Pallas. Airy, returning to the satellites, obtained the value in 1837; a

1

1

1046.77

result confirmed by Bessel's determination, 1047-87, and by Captain

1

Jacob's estimate, -both these results being also deduced

'1047.54

from observations of the satellites. Herr Krüger's estimate, obtained from a series of most careful investigations of Themis (one of the minor planets) gives The mean of the four last-named

values (1047-34)

1

1047.16

may safely be accepted as a very close approximation to the true mass of the largest planet of the solar system. It is to be expected that the influence of Jupiter on Saturn, which seemed to Bouvard (before the discovery of Neptune) to indicate a will be satisfactorily accounted for by the value now assigned to Jupiter's mass.

1

mass of 1070'

The variable in Corona, whose appearance (sudden, we think, despite Mr. Hind's verdict) startled astronomers in May, and which had sunk to the 9th magnitude, increased in brightness to the 7th magnitude towards the end of August last; but Mr. Huggins's spectroscope revealed no traces of the bright lines which in May formed so marked a feature of the star's spectrum. The star has now returned to the 9th magnitude.

The

4. BOTANY AND VEGETABLE PHYSIOLOGY. ENGLAND.-Homologies of the Flowers of Coniferæ.-Mr. Andrew Murray has published an interesting paper on this subject, in which, at some length, he demonstrates that the male flowers are monopetalous and diandrous in the firs and pines, monopetalous and polyandrous in the cypresses and allied genera. female flower is also monopetalous. In the young state, the petal is a small bract, sometimes green, sometimes even more richly coloured than the petal of the male flower, always petaloid in texture, at least at the margins. The author supposes the envelopes to have the following homologies:-1. Outermost envelope, or its appendage, corresponds to, in ordinary dicotyledons, the petal; in conifers, to the bract. 2. Next envelope corresponds ordinarily to the disk; in conifers, to the scale. 3. First covering of the fruit, ordinarily the pericarp; in conifers, the wing of the seed.

4.

Second covering of the fruit, ordinarily mesocarp; in conifers, cellular substance between 3 and 5. 5. Third covering of fruit, ordinarily endocarp; in conifers, the testa. The remaining envelopes of the nucleus of the ovuli in the conifers (primine, secundine, &c.) in no respect differ in appearance or function from those of other seeds, and therefore need not be specially noted.

Lichenology.-The Reverend W. A. Leighton continues his series of papers on this subject in the 'Annals.' He has lately given a notice of the Abbé Coeman's essay on the Cladonia of the Herbarium of the great lichenologist, Acharius, and the results of the application to his own herbarium of a chemical test as a means of deciphering species of Lichens. The reaction which is found so useful, is that of hydrate of potash, which in certain cases produces a yellow colour, whilst in others there is no reaction, or only a slight fuscescence. In no case, says Mr. Leighton, is the reaction of greater utility than in the difficult tribe of Cladoniæ, that crux of lichenologists, where its application enables us with admirable precision and exactness to determine the various species, to redistribute the confounded species, and to refer to their proper systematic places the innumerable varieties and forms which may resemble each other in external character.

Climbing Plants.-Herr Fritz Müller, who is so well known among zoologists by his many valuable contributions to their science, and more especially by his essay, entitled 'Für Darwin,' writes from Desterro, in South Brazil, to Mr. Darwin, on the subject of his paper on the movements and habits of climbing plants. Mr. Darwin, in that paper, says that he has seen no tendrils formed by the modification of branches, and even seems to entertain some doubt whether such tendrils exist. Herr Müller gives an account of various plants which are known to him exhibiting this structural phenomenon, and traces the following stages in the development of branch-climbers:-1. Plants supporting themselves only by their branches stretched out at right angles, for example, Chiococca. 2. Plants clasping a support with their branches unmodified, Securidaca (Hippocratia). 3. Plants climbing with the tendril-like ends of their branches. According to Endlicher, this is the case with Helinus (ramulorum apicis cirrhosis scandens"). 4. Plants with highly modified tendrils, which may, however, be transformed again into branches, for example, Hecastaphyllum, a Papillionaceous plant. 5. Plants with tendrils used exclusively for climbing, Strychnos, Caulotretus. The letter contains many other interesting observations, which may be read in full in the Linnæan Society's 'Journal' of November 29th. With respect to the thickness of the support which can be ascended by spirally twining plants, Herr Müller states that he has