spoke of the formation of the Botanic Garden in Calcutta in 1787, and of the successive superintendents-William Roxborough, Nathaniel Wallich, and William Griffith. After mentioning other early workers in the field of Indian botany, he passed to a discussion of the splendid work done by Sir Joseph Hooker. Since that event, he said, the most important botanical work done in India has been that of C. B. Clarke. The preservation in good condition of a type specimen is, from the point of view of a systematic botanist, as important as the preservation to the British merchant of the standard pound weight and the standard yard measure, on which the operations of British commerce depend, and yet the only place available for that purpose was an old dwelling office on Kew Green, to which a cheap additional wing had been built. "In behalf of the flora of India," he said, "I venture to express the hope that the provision of a proper home for its types may receive early and favorable consideration of the holders of the national purse strings." In conclusion he described the forest department, which he styled "one of the great economic enterprises connected with botany in India." After showing that the ordinary forest officer educated in England now arrives in India without sufficient knowledge to enable him to recognize from their botanical characters the bestmarked Indian trees, he explained this condition by saying: "The general decadence of the teaching of systematic botany in England during the past twenty years is, perhaps, to some extent the cause of the low estimation in which the science is held by the authorities of the Indian forest department."

The following-named papers were then read and discussed before the section: Some Methods for Use in the Culture of Alga and on the Growth of Oscillaria in Hanging Drops of Silica Jelly and On Horn-destroying Fungus, by Marshall Ward; On the Influence of the Temperature of Liquid Hydrogen on the Germinative Power of Seeds, by Sir W. Thistleton Dyer; On the Phosphorous-containing Elements in Yeast and On the Sexuality of the Fungi, by Harold Wager; On Bulgaria polymorpha as a Wood-destroying Fungus and On India Rubber, by R. H. Biffen; On a Disease of Tradescantia, by A. Howard; On the Localization of the Irritability of Geotropic Organs, by Francis Darwin; The Results of Studies in Araccal, by Douglas Campbell; Studies in the Morphology and Life History of the Indo-Ceylonese Podostemaccæ, by John C. Willis; On Fern Sporangia and Spores, by F. O. Bower; The Jurassic Flora of Britain and A New Genus of Palæozoic Plants, by A. C. Seward; The Intumescences of Hibiscus vitifolius, by Miss E. Dale; The Maiden-hair Tree (Ginkgo biloba), by A. C. Seward and Miss J. Gowan; Some Isolated Observations bearing on the Function of Latex, by J. Parkin; and Stem Structure in Schizaceæ, Gleicheniaceæ, and Hymenophyllaceae, by L. A. Bootle.

Affiliation with the French Association.An interesting feature of the Dover meeting was the visit of the French association to Dover and the return visit by the British association to Boulogne. On Sept. 16 nearly 300 members of the French association and of the Société Geologique de Belge arrived at Dover, and were received by the officers of the British association with appropriate words of welcome, Sir Michael Foster saying: By the friends of science, by the friends of humanity, this day of the reunion of the two associations will always be truly regarded as a great festival." After a reception at the Town Hall, the visiting scientists gathered with

ASTRONOMICAL PROGRESS IN 1899.

the sections of their choice and later met in common with the association at luncheon, when again addresses of felicitation were made by the higher officers of each association. Also on Sept. 20 the officers and about 100 members of the French association, together with the president and some of the chief officers of the British association, were received and entertained by the mayor and corporation of Canterbury. The return visit of the president, officials, and about 250 members of the British association to the French association gathered at Boulogne was made on Sept. 21. On their arrival they were entertained at a breakfast in the Casino, and later were officially welcomed by the mayor of Boulogne. The British members then attended the sessions of the French association, presenting papers and taking part in the discussions. A banquet, at which happy expressions of good feeling were conspicuous, brought the event to a close.

On Sept. 15 an evening lecture on La Vibration Nerveuse was delivered in French by Prof. Charles Richet, and on Sept. 18 an evening lecture on the Centenary of the Electric Current was delivered by Prof. J. A. Fleming. The last-named was made conspicuous by the exchanges of congratulatory telegrams between the British association and the Congress of Electricians assembled in Como, Italy, to celebrate the centenary of Volta's electric discoveries, and also by the exchange of messages by the Marconi system of wireless telegraphy with the French association.

66

Attendance and Grants.-According to Nature, the meeting was a great success, especially when the size of the town and the fact that it is the most ambitious effort the town has ever made are considered." The attendance was 1,403, distributed as follows: Old life members, 296; new life members, 20; old annual members, 324; new annual members, 67; associates, 549; ladies, 120; and corresponding and foreign members, 27. In grants for research £1,115 was distributed among the sections as follows: Mathematics, £215; chemistry, £90; geology, £95; zoology, £355; geography, £100; economic science and statisties, £5; anthropology, £140; physiology, £75; botany, £20; and corresponding societies, £20.

Invita

Next Meeting. The association will meet in 1900 in Bradford, beginning on Sept. 5. tions to hold the meeting in 1901 in Belfast and in Cork were presented, but for special reasons the meeting in that year had been predetermined for Glasgow. Sir William Turner, M. B., LL. D., D. C. L., F. R. S., and F. R. S. E., Professor of Anatomy in the University of Edinburgh, was appointed president for the Bradford meeting. The following persons were invited to serve as vicepresidents: The Earl of Scarborough, the Duke of Devonshire, the Marquis of Ripon, the Bishop of Ripon, Lord Masham, the Mayor of Bradford, the Hon. H. E. Butler, Sir Alexander Binnie, Prof. Arthur W. Rücker, and Prof. T. E. Thorpe; general secretaries, Sir W. Roberts-Austen and Edward A. Schäfer; assistant general secretary, G. Griffin: general treasurer, Carey Foster.

ASTRONOMICAL PROGRESS IN 1899. The advancement in astronomy the past year was eminently satisfactory.

The Sun. So intense is the glare surrounding the Sun in a cloudless sky that no instrument yet devised enables astronomers to make observations of the various phenomena immediately surrounding it, except the prominences or protuberances, which can be seen and leisurely studied by means of the spectroscope. The other phenomena surrounding the Sun-the chromosphere, the corona, the streamers (curved, straight,

radial, and tangential)—though very bright, can not be seen except when the Sun is totally eclipsed and the observer near the center of the Moon's shadow. The making of long journeys, often of many thousand miles, to observe a total eclipse is not for observing the Sun itself, which would be impossible, as it is entirely covered by the Moon, but to study, with telescope, spectroscope, and photographic camera, the Sun's immediate surroundings.

On Jan. 22, 1898, a large party from several countries visited India to observe a total solar eclipse, which at every station selected was successfully observed. The result of all the observations has just been published in book form, with many elaborate illustrations, by the British Astronomical Association of London. It appears that the observations were almost exclusively photographic, and were a great success. On several of the plates the flash-light spectrum, and on others the corona spectrum, are clearly seen, and also on plates exposed during partial phase the Fraunhofer dark spectrum bordered with dark lines. On some of the plates the flash-spectrum lines in the ultra-violet are beautifully defined, and can be traced as far as wave length 3242. In this region from H more than 218 lines can be counted, and the wave lengths of all measured. A great many of the lines were due to iron, calcium, and magnesium. Three of the strongest lines have been identified by Mr. Jewell, at Johns Hopkins University, as due to the rare element titanium, which, instead of being confined to the flash layer, extended as high in the chromosphere as hydrogen, and also in the prominences, which are eruptions from the chromosphere, extending to a height of 100,000 miles, and were plainly visible to the naked eye during the totality of the eclipse of 1869. The coronium line, to produce which no substance has yet been found on the Earth, was traced to a height of 160,000 miles. This eclipse has confirmed what several previous ones have shownthat the corona, chromosphere, prominences, etc., belong to the Sun, and not to the Moon.

The grandest problem in astronomy is to measure the Sun's distance from the Earth. It was formerly thought that the problem was solved over one hundred years ago, and that the distance was 95,000,000 miles, but is now thought to be about 93,000,000. Millions of dollars were spent to observe the transits of Venus of 1874 and 1878 for this purpose, but the discussion of the observations still left a possible error of 200,000 miles. Now, thanks to the discovery of an insignificant asteroid, by the first day of the twentieth century (Jan. 1, 1901) the doubt will be reduced 75 per cent., as described under Asteroids.

The month of September, 1898, was rendered memorable to solar physicists by the sudden appearance of one of the largest Sun spots on record. As it appeared during the period of minimum Sun-spot activity, it created far greater interest than if it had occurred during the maximum period, and has created a distrust as to the existence of the eleven-year period of Sun spots. It first appeared on the east limb of the Sun on Sept. 2, and on the following day it assumed gigantic proportions, equal to 1,400,000,000 square miles. On the 10th the spot covered an area of only 24,000,000 square miles. During its passage across the central meridian of the solar disk the northern regions of the Earth were treated to one of the most magnificent auroral displays seen for many years. The simultaneousness of the two phenomena goes far to estab

lish the truth of the theory long entertained that there is a connection between them. At the same time there was a sharp disturbance of the magnetic needle in various countries, and of the telegraph wires, lasting four hours. The movement of the needle in declination extended through an are of more than a degree. When it is considered that Sun spots last many days, and often weeks, it seems to militate against the truth of the above-mentioned theory that the aurora should last but a day, and often much less, and magnetic intensity but four hours.

Photographic Astronomy.-Dr. E. E. Barnard, of the Yerkes Observatory, Williams Bay, Wisconsin, has published two papers, the first being a description of one of his photographs of the Milky Way, near Theta Ophiuchi, accompanied by a print of it, which reveals much of the intricate structure of that portion of the starry girdle. Certain appearances in the photograph appear to justify the belief that in this portion of the galaxy a substratum of a dual nebulosity exists, while huge dark rifts and black lines suggest the idea that the photograph actually pierced through the luminous girdle into the blackness and starless space beyond. These peculiarities, he says, strongly remind one of the appearances often seen in the umbra of Sun spots, where a dark halo lies in the dark central spot, as if the cavity was partly veiled with some sort of medium, with apertures in it. His second paper can be found in the March number of the AstroPhysical Journal.

Prof. E. C. Pickering, of Harvard Observatory, has lately received from its station at Arequipa, Peru, a series of the most successful photographs of the heavens yet taken. One plate especially, 14 X 18 inches, taken with the Bruce photographic telescope, shows with marvelous clearness and exactness as to magnitudes and position the enormous number of 400,000 stars, all depicted by a single exposure of probably several hours' duration. Miss Catharine Bruce, of New York, gave the professor $50,000 for the construction of this celebrated photographic telescope of unique construction. The object glass corrected for actinism (thus being useless for visual work) is -24 inches in diameter, and has only a 12-foot focus. The professor is now constructing a telescope, going to the other extreme as to focal length, to be about 175 feet, to lie horizontal and immovable. The light from objects to be observed is to be reflected from a plane mirror driven by clockwork, equatorially mounted, and regulated to sidereal time; or the photographic plate itself may be moved by clockwork, to counteract the rotational velocity of the Earth, that a star may be held during exposure on the meridional wire in the eyepiece. The great Yerkes telescope, with a 40-inch object glass, is 67 feet long, while this new instrument, with an objective only 13 inches in diameter, will be more than 100 feet longer. One advantage possessed by the long telescope will be the immense size of the photographed Moon and planets; that of the former will be about 15 inches in diameter, while with ordinary telescopes 3 inches is about the limit. The great telescope building in Paris for the Exposition is to have an object glass 50 inches in diameter, and to be about 100 feet in length. Enlarging photographs, especially of the Moon, is often done, but always at the expense of distinctness; but as the Moon taken with the long telescope will be 15 inches in diameter, no further details of value would be gained by enlarging.

It has been known for many years that in

order to deal most effectively with stellar phenomena a field of much greater width was necessary than from 10 to 15 degrees, as formerly practiced. But not until the publication of Mr. Dallmeyer's stigmatic lens, in 1897, was one able to chart wide sky areas without great distortion near the margin of the field. A photograph taken by Mrs. Maunder, of England, with a stigmatic lens only 1 inch in diameter and 9 inches in focal length, has been published. The field shown is 37 degrees on a side and 50 degrees diagonally. A set of 40 plates of the same angular aperture as the foregoing, but of larger scale, would provide a more complete chart of the heavens than any that we now possess in a small compass and at very little expense. The work lies very easily within the powers of many small private observatories.

The Planets. No remarkable advance in our knowledge of the planets was made during the year. Prof. Schiaparelli has published his fifth memoir on the planet Mars, without increasing our knowledge of the cause of its surface markings, which has excited the world during the past two decades. The true explanation of the changes visible on his surface at different seasons, the duplication of the so-called canals, which some astronomers, with indifferent optical appliances, profess to see easily, while others with far superior means can not see them, seems as far off as ever. The gemination of the canals is believed by the majority of astronomers to be an optical illusion, inherent in some eyes, especially if wearied by overwork, the defect being in the eye, and not in the telescope. Some observers say they see markings on Mercury and Venus, and thence deduce conclusions as to their rotation periods. Herr Leo Brenner says he has conclusive evidence that Mercury rotates on its axis once in thirty-three days and forty-five minutes. The general opinion that this period is but about twenty-four hours has long held sway. A day on Venus has been supposed to be about the same as ours, yet some observers now assert that her period of rotation is 224.7 days. In the presence of such discrepant conclusions it must be held that nothing is positively known as to the period of either planet, and the same remark applies to the periods of Uranus and Neptune, and all satellites except our own.

Satellites of Mars.-No. 7, Vol. IX, of the Transactions of the British Astronomical Association contains some new and interesting facts regarding the satellites of Mars, and, as they are totally unlike anything known elsewhere in the solar system, a few are briefly noticed:

Phobos. This little speck of a world is only 10 or 15 miles in diameter (some estimate it at 7 miles), revolves around Mars in 7h 39m, and therefore must move across the sky at the rate of 47° an hour. But, as it rises in the west and sets in the east, its apparent motion across the sky will be the difference between its own and the rotational velocity of Mars, which is 14° 30' an hour, or 32° 30'. Owing to the satellite's rapid motion, combined with its large parallax, it is above the horizon at the equator for 4h 15m, and below it for 6h 45m. Owing to the combined motion of both satellite and planet, it requires 11h 6m for Phobos to return to the same meridian, during which time it goes through all the phases, from new Moon to full, and from full to new, that our Moon does in twenty-nine and a half days. As the length of a night on Mars is 12h 18m, Phobos can be seen by the same observer twice full and once new, or once full and twice new. The eclipses of both the Sun and the satellite

occur with great frequency. So rapid is the phase change of Phobos that at a zenithal central eclipse, which lasts 54m, the satellite may be seen to enter the shadow in a phase a little short of full and emerge a little past full, each phase being 0.937. When Phobos is in the zenith it appears more than twice as large as on the horizon. If Phobos and Deimos are exactly in the plane of the planet's equator, Deimos will be occulted by Phobos about every ten hours, the moons approaching each other from opposite directions. The average distance of Phobos from the surface of Mars is only 3,730 miles. Assuming that the satellite turns to Mars the same phase as does our Moon to the Earth, the planet will appear immovably fixed in the sky, with a disk one thousand times larger than is shown by our Moon. A Martian astronomer (if there is one) could with a powerful telescope bring the satellite within one mile.

Deimos.-This satellite completes a revolution round the planet in 30h 15m, rising, as does our Moon, in the east and setting in the west, traveling across the sky at the slow rate of 2° 45', equal to the difference between its own hourly velocity of 11° 53′ among the stars and the hourly rotational velocity of the planet of 14° 37'. If the satellite is supposed to rise when full, it can be seen twice full and twice new before it sets. In the zenith Deimos from the surface of Mars will appear about one third larger than when in the horizon. Its diameter is uncertain, but is considered to be from 10 to 15 miles, too small ever to eclipse the Sun totally, though it will cross the solar disk about 130 times during a Martian year. Of course, it must occasionally happen that both satellites will transit the Sun at the same time, both passing across the sky from west to east, Deimos slowly and Phobos rapidly. If it be assumed that Deimos turns the same face to Mars, which is probable, the planet would appear fixed in the sky, the stars sailing by in regular order. As Deimos is more distant from the surface of Mars than is Phobos, it will appear somewhat smaller, but would still appear vastly larger than our Moon appears to us.

The

Of Jupiter little is known that was not previously recorded. Mr. Denning, of England, has examined his rotation period as given by dark and bright spots in the region of the equator, which furnishes a mean period of 9h 50m 23s, against 9h 50m 30s as previously adopted. period of the famous red spot, which is still faintly visible, from 17,414 revolutions, is 9h 55m 39.4s, but is not uniform. The variation is not great-perhaps not greater than might be expected from the nature of the observations.

Nothing but ordinary routine observations have been made on the planets Uranus and Neptune to determine their periods of rotation, but Dr. E. E. Barnard, of the Yerkes Observatory, has made a series of elaborate observations with the mammoth telescope on Neptune's satellite, the measures of which have enabled Prof. Hall to improve the elements of its orbit. He finds the mass of Neptune to be 1997, that of the Sun being 1.

Asteroids. Since the last report the following asteroids have received numbers to replace the provisional letters given in the last volume:

DT 436, discovered by Wolf.

DU 438, discovered by Charlois, Nov. 8, 1898. EB 439, discovered by Coddington, Oct. 14, 1898. EC 440, discovered by Coddington, Oct. 14, 1898. ED 441, discovered by Charlois, Dec. 9, 1898. EE 442, discovered by Wolf, Feb. 15, 1899. EF 443, discovered by Wolf, Feb. 17, 1899. EL 444, discovered by Coggia, March 31, 1899. Nearly a dozen others were found and received provisional letters, but they proved to be those discovered several years ago. The following asteroids have received names: No. 420, Bertholda; No. 421, Zähringia; No. 422, Berdina; No. 428, Monathia; No. 433, Eros; No. 439, Ohio.

An asteroid discovered six years ago, No. 366, which has had only a provisional number, has lately been named Vincentina.

Asteroid 433 (DQ), about which so much interest is taken on account of its anomalous orbit and the value it will have for astronomy, has been named Eros. A brief notice of its discovery was given in the last volume of the Annual Cyclopædia, before the great value of the discov ery was fully appreciated or its orbit accurately computed. The number of asteroids now known is about 450, all between the orbits of Mars and Jupiter except the one under discussion. The labor of keeping track of so many is great, and the announcement of the discovery of another is treated with indifference bordering on disgust; but the discovery of Eros has opened a broad field for speculation, as it may be the forerunner of others moving in the same or similar orbits. It was discovered by photography; its trail, a long one, was found on the plate with two short ones, which immediately indicated that if it was not that of a comet then there must be an asteroid with an orbit unlike any of the others. A few observations showed that two thirds of its orbit lies between the orbits of the Earth and Mars, instead of between Mars and Jupiter. At certain times it can approach nearer the Earth than any heavenly body except the Moon, and be just visible to the naked eye. It makes one of these nearest approaches only once in about thirty-one years, when its parallax will amount to almost a minute; and of all the means that can be used for the ascertainment of the Sun's distance from the Earth, including the transits of Venus, this little insignificant world is worth the most. We have always considered Mars as our nearest outside and Venus the nearest inside neighbor, but now it is Eros and Venus. At its least distance from the Earth Eros is only 0.15, in terms of the Earth's distance from the Sun, as compared with 0.27 for Venus in transit, equal to 25,650,000 miles, and 0.38 for Mars in perihelion, equal to 35,300,000 miles, or only 14.000.000 for Eros.

The Earth passes the longitude of the asteroid's perihelion (nearest the Sun) on Jan. 22, and in order that the Earth and the asteroid be nearest together the asteroid must pass perihelion on or near that date, which it will not do till 1931. But, fortunately, quite a near approach will take place in December, 1900, the distance being 0.33, at which the little planet will be between the eighth and ninth magnitude. When discovered it was of the eleventh magnitude, and three and a half years previous it must have been of the sixth and a half. The diameter of the little world is about 17 miles.

If its parallax can be obtained, Kepler's third law gives at once the distance of the Earth from the Sun, which is the "yardstick" that "determines the distances of all the planets from the

orbital velocities." Prof. Pickering found the trail of Eros on 13 plates exposed during 1893-'96, the photo-magnitudes varying from 8.2 to 12.5. During the search for Eros on the plates Mrs. Fleming found images of two variable stars, one of which fails to appear on 10 plates. All the photographs on which Eros was found were taken with doublets. Had lenses of the usual form been used, with a field only 2 degrees in diameter, all the images of Eros would have fallen outside the plates.

Dr. S. C. Chandler, editor of the Astronomical Journal, has computed the following elements of Eros, using recent observations combined with positions found on Harvard plates in 1894:

EPOCH 1898, AUG. 31.5, GREENWICH MEAN TIME.
Mean anomaly.
Node to perihelion.
Longitude of node
Inclination of orbit

221° 35' 45.6" 177° 37' 56.0" 303° 31' 57.1" 10° 50' 11.8"

Angle of eccentricity... 12° 52′ 9.8"
Daily motion..

Logarithm of mean distance
Period of revolution...

1898.0

2015.2326" 0.1637876 643.10 days

Saturn's Ninth Satellite.-Attempts have been made to discover new satellites to the planets by photography, but they have failed, from the low rapidity of the lenses employed. On Aug. 16, 17, 18, 1898, four plates were exposed for two hours each, with the lens presented to Harvard College Observatory by Miss Catharine Bruce, of New York, which has 24-inch aperture and only 13 feet 4 inches focal length. One hundred thousand stars appeared on each plate. The photographs were examined two at a time, one superimposed on the other, and placed film to film, so that each star was represented by two contiguous dots, the satellite showing itself by a single dot, sharing in the motion of Saturn relatively to the stars. The position of the satellite is nearly the same on the two plates taken on Aug. 16. On Aug. 17 it followed this position 35" of arc, and was south 19". On Aug. 18 it followed 72", and south 43". Its motion was direct, but slower than that of Saturn, and nearly in the same direction. It therefore can not be an asteroid, but must be either a ninth satellite to Saturn or an ultra-Neptunian planet. Prof. Pickering, who has thoroughly investigated all the circumstances of this strange and unexpected discovery, thinks the latter supposition exceedingly improbable. It was at first identified with a faint object found on the plates taken in 1897, and the period of revolution around Saturn (seventeen months) was thence derived; but this is not confirmed, and the period is now in doubt. The position angle in May, 1899, was between 280° and 290°, and the distance between 20 and 30 minutes. The uncertainties will probably be diminished when plates taken at the Harvard Observatory station at Arequipa, Peru, on Sept. 15, 16, and 17, 1898, are received at Harvard College Observatory. The apparent orbit of the supposed satellite is a very elongated ellipse. From comparisons with Hyperion, the faintest of his satellites, the magnitude of the new one is estimated at 15.5. As seen from Saturn, it would appear of the sixth magnitude, or as faint as the faintest star visible to the naked eye. If its reflecting power is the same as his largest satellite, Titan, its diameter is estimated to be only about 200 miles. Prof. William H. Pickering, its discoverer, suggests the name Phoebe, sister of Saturn. It thus appears that this unique planet is adorned with 9 moons, environed in 3 rings, and sometimes 5.

Nebula.-In four years of the five that Dr. Lewis Swift has been director of the Lowe Observatory, at Echo Mountain, California, he has discovered and catalogued 350 new nebulæ. Some of these are very interesting, and deserve thorough investigation with the spectroscope and the largest telescopes. Special attention is drawn to a few, as follows:

One which he calls a nebulous nebula, in right ascension 23h 29m, declination south 36° 29′, has the appearance of a central elongated nebula, with sharp outline, centrally superimposed on another very much the larger and of unimagined faintness. It is probably the only one in the heavens that bears any resemblance to it, and raises the question whether there can be any connection between the two, if two there are. Astronomers are acquainted with several nebulous stars that is, a star in the center of a nebulous atmosphere but a nebula in the center of a nebulous atmosphere is a novelty. One in right ascension Oh 46m 458, declination south 35° 0.5', presents the curious aspect of a double nebulous Uranus. Two others, which he calls hair-line nebulæ, resembles, except in color, a short piece of horsehair. They are doubtless disk nebulæ, their thin edges being presented exactly to our line of sight. Their places for A. D. 1900 are right ascension 3h 31m, declination south 34° 47', and right ascension 5h 29m 20s, declination south 36° 28'.

Prof. Herbert A. Howe, director of the Chamberlain Observatory, University Park, Colorado, has recently discovered 22 new ones while obtaining micrometrical places of some previously discovered.

Dr. De Lisle Stewart has 46 novæ on photograph plates, taken with the Bruce photographic telescope at the Harvard Observatory station, Peru, in the latter part of 1898. The group is between right ascension 3h 10m and 3h 50m, and declination south 49° 50′ and 55° 40′. Only two appear in Dreyer's New General Catalogue of Nebula viz., 1311 and 1356. There are several nebulous regions in the celestial vault that suggest the idea that they may be offshoots from one, or at least are connected together, the connecting links being invisible from faintness and distance. Isaac Roberts has lately reproduced a photograph of No. 2239, between right ascension 6h 24m and 6h 23m and north declination 4° 24.8′ and 5° 56.5′ in the constellation Monoceros, with an exposure of 2h 45m, a depiction of nebulosity, extending like a cloud, but broken up into wisps, streamers, and curdling masses densely dotted with stars on its surface and the surrounding region. Several remarkable black tortuous rifts meander through the nebulosity, their margins sharply delineated.

Hind's variable nebula is the only well-authenticated instance of a nebula varying in brightness, somewhat analogous to variable stars. It is in Taurus, and is No. 1555 of the catalogue of nebulæ. The following observations were made with the 40-inch telescope of the Yerkes Observatory by Dr. Barnard: When discovered by Prof. Hind, of England, many years ago this nebula was conspicuous in an ordinary telescope, but in 1868 it had vanished from the largest telescopes. Mr. Burnham saw it as a very faint nebula, in 1890, in the 36-inch telescope at the Lick Observatory. In February, 1895, it was an easy object, but it had vanished the following September. On Sept. 28, 1897, it could be detected at good intervals of seeing, but with extremest difficulty, with the great Yerkes telescope. Dr. Scheiner, with an exposure of seven and a

half hours, obtained a good photograph of the spectrum of the great nebula in Andromeda from to H. A comparison between this and the solar spectrum disclosed a surprising agreement between them. No trace of bright lines (a sure indication of the presence of gas) was present, so that the interstellar space in the nebula is not apparently occupied by gaseous matter. The doctor calls, attention to the analogy between the Andromeda nebula and the Milky Way. The streams and irregularities of the latter he regards as of special structure, instead of a ring system. The ground for this view is the fact that all ring nebulæ give gaseous spectra, in contrast with the spiral nebula.

HB

Dr. J. E. Keeler, director of the Lick Observatory, on the night of Dec. 12, 1898, observed the Orion nebula with the spectroscope attached to the 36-inch telescope. The slit was first placed on the nebulosity surrounding the star (Bond 734). The night being hazy, only a single line was visible, identified as HB. The slit was then placed on the Huyghenian region near the trapezium, which showed the usual spectrum. and the second nebular line (a) =4959 were about equally bright, but the chief line (a) = = 5007 was several times brighter than either. The intensity of the spectrum was then diminished by contracting the vertical aperture of the spectroscope, the resolving power remaining unchanged. When the brightness was sufficiently reduced HB and the second line disappeared, the chief nebular line alone being visible. In other words, with a sufficiently feeble spectrum the H8 line was alone visible in one part of the nebula, and the chief line alone in another part. The doctor pronounces the result inexplicable on physiological grounds, and thinks it can only be due to real difference in the spectrum of the nebula itself.

Recent observations of the star Mira (which varies from the second magnitude to invisibility in eleven months) by Prof. Campbell, with the Mills spectrograph attached to the 36-inch telescope at the Lick Observatory, show that the star is retrograding from us at the rate of 38.5 miles a second. This result was obtained from the dark lines only, as some of the bright lines show considerable displacement toward the violet. He was unable to perceive any trace of the green line of hydrogen, yet the two succeeding members glowed with unexpected intensity. The absence of the lower radiations constitutes an anomaly of the most pronounced kind, and is accounted for by the diverse character of the hydrogen spectrum in nebulæ and bright helium

stars.

Comets. In 1898 ten comets were observed, one more than ever before recorded, while up to Oct. 20 three only were discovered in 1899, and two of these were expected.

Comet I 1898 (Brooks).—This interesting comet was discovered by William R. Brooks at Smith Observatory, Geneva, N. Y., on Oct. 20, 1898, in the constellation Draco, in right ascension 14h 35m 10s, declination north 60° 26'. For a telescopic comet it was large and bright, being visible with a 3-inch telescope, in presence of a halfmoon. For a while after discovery it was supposed to be a return of Schaeberle's comet of 1881 IV, so similar were their orbital elements. Further observations, continued longer, afforded evidence that it was moving in a parabola, and therefore was a visitor to our system for the first and last time. Similarity of element, however, leads strongly to the supposition that they belong to the same family. The following are the latest, and presumably the most ac