De Vico's comet of short period has not been seen since 1844. This body is regarded by Leverrier as identical with the comet discovered by Lahire in 1678. It is situated most favorably for observation when the perihelion passage occurs about September 4th, and it is remarkable that those of 1678 and 1844 took place within a few days of the most favorable date. A possible reason for the non-recovery of the comet at any recent return was given in Nature for July 27, 1876. The orbit of De Vico's comet approaches very near to the orbit of Mars at two points falling near 42° and 287° heliocentric longitude. At the former point the distance between the two orbits is about 2,000,000 miles, and at the latter somewhat less than 1,000,000; "and it is to be borne in mind that these distances, small as they are, may have been diminished very sensibly by the effect of accumulated perturbation since 1855, beyond which we have no calculation of the effects of planetary attraction. If the mean diurnal motion in 1855 were as large as 652.05", a value considerably within Brünnow's suggested limits, the comet might have come into extremely close proximity to Mars at the end of August, 1866, in about 42.3° heliocentric longitude."

Meteors.-Between ten and twelve o'clock on the night of April 18, 1876, meteors were seen in unusual numbers near Ellettsville, Ind. A large majority of those whose tracks were well observed were conformable to the radiant in Lyra. Several were remarkably brilliant, apparently equal to stars of the first or second magnitude. The meteors of this epoch are supposed to be derived from the first comet of 1861, and to move in the same orbit.

Watch was kept for meteors at York, England, on the nights of August 10th, 11th, 12th, and 14th. Several nights preceding the 10th were cloudy, and the 11th was very hazy. The brightness of the moonlight also interfered with the observations, except on the 14th, which may be regarded as the close of the August epoch. The hourly numbers radiating from Perseus, seen by a single observer,

on the four nights were 18, 6, 9, 7. There was, therefore, a regular decrease from the 10th, the apparent exception on the 11th being due to the haze. Making all allowance for unfavorable circumstances, Prof. Herschel thinks the shower of 1876 indicates a minimum.

On the evening of October 18, 1876, from about half-past seven to nine o'clock, meteors were seen in greater numbers than usual at Bloomington, Ind. The maximum number for one observer was eleven per hour. They all diverged from the vicinity of a point between Taurus and Auriga. Most of the meteors were small, though two were seen of At Newburyport, extraordinary magnitude. Mass., on the same night, at two o'clock A. M., a bolide was observed to start from the same part of the heavens.

It was half the apparent size of the moon, which it rivaled in brightness, the smallest objects being visible in the intense white light of about two seconds' duration. It left a train 10° long and visible over a quarter of an hour. While the train one-fourth of a degree wide, which remained was being observed a large number of smaller meteors passed, as often as one a minute, over the same field, one or two of them leaving a slight train.

The meteors of November 14th move in the orbit of Tempel's comet (1866), and are the débris resulting from its disintegration. The comet, together with the principal swarm of meteors which immediately follow it, is now approaching its aphelion near the orbit of Uranus. As the existence, however, of more than one cluster in the same orbit has been clearly indicated, a yearly watch will be necessary, while passing the node, in order to discover the law of meteoric distribution. "On the morning of November 14th" (according to Prof. Newton), "between twelve and one o'clock, the sky at New Haven was partly clear. Out of about twelve meteors seen, three might be called conformable to the radiant in Leo. Shortly after one o'clock the sky became wholly overcast."

Aerolites and Meteoric Fire-balls.--In the American Journal of Science for June, 1876, Prof. J. Lawrence Smith, of Louisville, Ky., describes a fire-ball seen by himself and many other observers to pass Louisville on the evening of January 31st, at half-past five o'clock. The meteor was first seen about 60° above the horizon: its direction was from northwest to southeast; duration of flight. two or three seconds; apparent size, one-sixteenth that of the moon's disk. The bolids exploded about 10° above the horizon, when all the fragments disappeared, except the largest, which continued its course very nearly to the horizon.

A fall of aerolites took place near Ställdalen, in Sweden, June 28, 1876, between the hours of eleven and twelve A. M. The fall of the stones was accompanied by a brilliant light, though the day was cloudless. Two or three loud detonations were heard, after which the

meteorites were seen to fall by eight or ten persons. Twelve fragments were found, the largest of which weighed four and a half pounds.

On the 25th of June, between nine and ten o'clock A. M., a small meteorite fell in Kansas City, Mo.

A large fire-ball, moving in a westerly direction, passed over the States of Michigan and Wisconsin, on Saturday evening, July 8th, about fifteen minutes before nine o'clock (Chicago time). It was seen by Mr. E. L. Linsley, at Stratford, Conn.; Mr. Benjamin Vail, at Henryville, Clarke County, Ind.; Mr. William L. Taylor, at Wolcottville, La Grange County, Ind.; Rev. Robert Beer, at Valparaiso, Ind., and by many others in various parts of the Western and Northwestern States. From the observations of the persons named, with those of others who witnessed the phenomenon, it has been found that the course of the meteor was a few degrees north of west; that its height when first observed was certainly over 100 miles; that it passed vertically over the counties of Branch, St. Joseph, Cass, and Berrien, Mich.; that it did not reach the earth's surface, but passed out of the atmosphere in its cometary orbit about the sun; and that its nearest approach to the earth could not have been less than 70 miles.

The meteor was apparently one of great magnitude, as its brilliancy was compared by observers to "the glare of a calcium-light." The body left a luminous track in the atmosphere, which continued visible at least thirty minutes.

On Saturday morning, December 16th, at 12h 45m, an immense ball of fire was seen from San Francisco, Cal. When first observed it was descending rapidly, and, a few moments afterward, it fell into the sea at apparently no great distance from the shore. The fall was followed by a loud explosion.

On Thursday evening, December 21st, at 8 45, Cincinnati time, a meteor of extraordinary magnitude passed over the States of Kansas, Missouri, Illinois, Indiana, Ohio, and Pennsylvania. Its course was 17° or 18° north of east, and it passed almost vertically over Fort Riley, Kan.; Weston, Mo.; Peoria, Ill.; Rochester, Ind.; Toledo, Ohio, and Erie, Pa., somewhat south, however, of the place last named. At Bloomington, Ind., the meteor was first seen at a point about 10° south of west, and less than 5° above the horizon. It appeared as a single globe of light, surpass ing the moon in magnitude and brightness. When northwest of Bloomington, Ind., or soon after it had passed the zenith of Peoria, Ill., the body was seen to separate into numerous fragments. The apparent size, however, of the principal mass, was not sensibly diminished. The explosion was followed by a violent detonation, resembling a heavy clap of thunder. The height of the meteor when the explosion occurred was estimated at from 45 to 48 miles.

The fragments thrown off by the explosion were more retarded than the principal mass by the resistance of the atmosphere, so that, in the last part of the course, the appearance was that of an elongated cluster about 3° in breadth and 20° in length. The height of the meteor when first seen was probably 70 or 75 miles; length of the visible track, 1,000 miles; time of flight, two minutes; velocity with reference to the earth's surface, 8 miles per second; true orbital velocity, between 22 and 25 miles per second. The interval between the disappearance of the meteor and the violent detonation as observed at Bloomington, Ind., was fifteen minutes, indicating a distance of about 180 miles. A fragment of the meteoric mass, weighing about a pound, was found three miles northwest of Rochester, Fulton County, Ind., on the following morning, December 22d.

Star Systems.-Polaris has long been known as a double star, its companion being of the ninth magnitude, and at a distance of eighteen seconds from the larger component. In 1869, M. de Boë, at Antwerp, detected two other companions, much nearer and fainter than that previously known. The observer sought, subsequently, to confirm his discovery, but his efforts, until recently, were without success. In 1876, using a six-inch equatorial, he rediscovered the two new stars, and the observation has been lately confirmed by that of Baron von Eithorn. The light of the new members of the system is probably variable.

The Binary Star Omega Leonis. - In the "Transactions" of the Royal Irish Academy, vol. xxvi., Dr. Doberck, of Markree Observatory, Ireland, has given the details of his elaborate determination of the elements of this binary system. The period is 111 years—considerably greater than that of Uranus; the eccentricity, 0.536.

Gamma Corona Australis.-Prof. Schiaparelli has recently measured this binary star with the eight-inch Merz equatorial of the Observatory of Brera, Milan, and, by comparing his own observations with those of Poweil, Sir John Herschel, and Jacob, has calculated its orbit. The periastron passage will take place in 1882; the orbital eccentricity is 0.6989, and the period of revolution 55.582 years-somewhat greater than that of Sirius.

Eta Cassiopeia.-During the past year, Dr. Doberck has rediscussed the observations of this star and obtained new elements differing considerably from those previously computed. The periastron passage will occur in the spring of 1909; the eccentricity is 0.5763; the period, 222.4 years; and the semi-axis major, 9.83". The parallax of Eta Cassiopeiæ, according to Struve, is of a second. It results from these data that the mean distance of the companion from the principal star is about 64 times the radius of the earth's orbit, and the mass of the system 5.25 times that of the sun. The distance and apparent magnitude of this binary

system are very nearly identical with those of 70 Ophiuchi, while the mass of the latter is less than that of the former in the ratio of three to five.

Sirius. From a discussion of the observations of the companion of Sirius, Dr. Auwers has found the period of revolution to be 49 years and 146 days; the semi-axis of the orbit, 37 times the distance of the earth from the sun; and the eccentricity, 0.6148-somewhat greater than that of Faye's comet. The mass of the companion is half that of the principal star; or, more exactly, the mass of Sirius is 13.76, and that of the telescopic star 6.71, the mass of the sun being unity. As the light of Sirius, according to Sir John Herschel, is 324 times that of an average star of the sixth magnitude, and as the satellite discovered by Clarke is of the ninth or tenth magnitude, the light of the latter must be much less than onethousandth part of that received from the principal star. The facts seem to indicate a remarkable difference between the physical constitution of Sirius and its satellite.

Procyon. It was stated, in our volume for 1874, that M. Otto Struve had discovered a small companion of Procyon, by which it was believed the anomalous motion of that star might be satisfactorily explained. Strangely enough, however, the most diligent search for this new star with the twenty-six-inch refractor of the Washington Observatory has been hitherto unsuccessful, although three other companions have been distinctly recognized by Profs. Newcomb and Holden; their distances from Procyon being 6", 9", and 10", respectively. The difference of atmospheric circumstances could scarcely explain the contradictory character of the observations at Pulkowa and Washington. We must conclude, therefore, that the observations of Struve were somehow erroneous, or that the light of the new star is variable.

Cincinnati Catalogue of New Double Stars. -The search for new double stars has been recently prosecuted with eminent success at the Cincinnati Observatory. As a first result of these labors, the director, Mr. Ormond Stone, has distributed a catalogue of fifty, all included in the zone between 8° and 40° south declination. They vary in distance between 0.8" and 8". The estimated magnitudes of the components are given, together with their distances asunder, and their angles of position. Variable Stars.-Dr. Gonld, Director of the Cordova Observatory, has found the period of a variable star in Musca to be less than that of any other variable hitherto determined. This star, at minimum, is entirely beyond the reach of unassisted vision even in the sky of Cordova, though at maximum it is distinctly visible. The period of variation is about thirty hours.

In February, 1876, M. Tisserand, Director of the Observatory of Toulouse, undertook a series of observations on the small stars near VOL. XVI.-4 A

the trapezium in Orion. The instrument used was the Foucault telescope of 31 inches aperture, then recently mounted. Especial attention was given to those stars which M. O. Struve had designated as variable, and not only were the suspicions of the Pulkowa observer for the most part confirmed, but in the case of several other stars in which he had detected no change variations of magnitude were clearly indicated. The existence of so many variable stars in this remarkable nebula will be regarded by astronomers as a fact of no ordinary interest and significance.

The Pleiades.-The report of the Council of the Royal Astronomical Society to the fifty-sixth annual meeting (1876) contains the following statements in regard to the Pleiades group, several members of which are found to be variable:

M. Wolf, of the Paris Observatory, has made a series of measurements of this interesting group of stars, including all visible through an object-glass of 0.31 millimetre aperture. The exact positions of the 53 stars observed by Bessel, referred to Eta distance, are given in a table containing the measTauri by differences of right ascension and polar surements of M. Wolf, compared with those of Bessel reduced to January 1, 1874. The relative magnitudes of these 53 principal stars have been determined with very great care, in order to detect any possible variation of brightness since Bessel's observations. M. Wolf has been able to detect no less than 499 stars around Eta Tauri, contained within a rectangle of 135 minutes of are in length and 90 minutes' breadth. These vary from the third to the fourteenth magnitude. The observed magnitudes have been compared with those in the catalogues of Jeauret, Lalande, Piazzi, Bessel, and Argelander; from which M. Wolf concludes that among the eight principal stars of the group, Merope and Atlas are decidedly variable, and Maia appears also to have increased in magnitude since the observations of Piazzi and Bessel. The five others show no evidence of variability, but some of the smaller stars have certainly changed their relative brightness since the former observations.

He concludes, from a comparison of the differences between his and Bessel's measurements of the 53 principal stars, that the Pleiades form a group whose members are physically connected one with the other; and, moreover, there appears to exist in the group a relative displacement of the stars, which direction to the diurnal motion, slightly diminishcarries the greater number of them in a contrary ing their polar distance. M. Wolf hopes that his two years' observations may serve as a certain basis, at a future period, for the determination of the proper motion of the separate components forming the Pleiades group.

Spectroscopic Observations.-Sir George B. Airy, the astronomer royal, has recently published the results of spectroscopic observations made at Greenwich for determining the motions of stars in the line of sight. The velocity of approach or recession of the stars observed is found by the displacements of the lines of known elements in their spectra; the estimated rates of motion being corrected for the earth's velocity resolved in the direction of the star. The rate of recession assigned to Sirius by these observations is 27 miles per second, or about 852,000,000 miles per annum

with Merope, but extending slightly toward the east; the other, more luminous, was about seven seconds of are from the star, on the same parallel, the diameter being about one second. From the month of November, 1874, to the end of February, 1875, the nebula was invisible, although it was looked for on many occasions when the sky was very favorable for the purpose. M. Wolf, therefore, considers that this nebula is certainly variable, with a moderately short period.

Knobel's Reference Catalogue of Astronomical Papers and Researches.-The thirty-sixth volume of the "Monthly Notices" of the Royal Astronomical Society contains, in its supplementary number, an elaborate and ex

It will be noticed that Alpha and Beta of the Great Bear (the two stars known as "the pointers") are moving in different directions. The former, which is nearer the pole, is approaching the sun; the latter is receding from it.

Nebula.-M. Stephan, Director of the Marseilles Observatory, has been recently devoting special attention to the search for new nebula. The result has been the discovery of 400 of these bodies, all of which had escaped the notice of former observers. The fact that they are generally small is favorable to the accurate determination of their positions-a point of great importance for the future investigation of their proper motions.

Supposed Changes in Messier's Nebula No. 17. -This nebula, which was discovered by Messier nearly a century since, has lately been the subject of critical study by Prof. Edward S. Holden, of the Washington Observatory. It was the object of these researches to determine whether the nebula has undergone any sensible changes since the date of the earliest trustworthy descriptions. The conclusion derived from an elaborate discussion is that, while the stars in and about the nebula have retained their relative positions, the part of the nebula known as the "Horseshoe" has moved with reference to the stars, and that, therefore, we have evidence of a change going on in this nebula." This may be a change in the nebula's internal structure, or it may be "the bodily shifting of the whole nebula in space in some plane inclined to the line of sight."

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Variable Nebula in the Pleiades.-Of this interesting object the "Monthly Notices" of the Royal Astronomical Society for February, 1876, says:

The most remarkable object of the group is the nebula around Merope. Discovered by M. Tempel in 1859, it has also been seen by Profs. D'Arrest and Schmidt, who were of opinion that the nebulosity must be variable. On March 7, 1874, it consisted of two portions, one of which was nearly concentric

astronomy. This catalogue, prepared by E. B. Knobel, Esq., consists of a list of references to all books, papers, and notes, relating to the following subjects:

1. Double Stars, including the Mathematical Investigation of the Orbits of Binary Systems. 2. Variable Stars.

3. Red Stars.

4. Nebula and Clusters.

5. Proper Motions of Stars.

6. Parallax and Distance of Stars. 7. Star Spectra.

The list of references is derived mainly from a systematic examination of the libraries of the Royal Society and the Royal Astronomical Society, the first of which is said to be peculiarly rich and complete in the transactions of scientific societies. The work was prepared, the compiler informs us, "in the hope that these references may be found useful to astronomers in guiding them to the particular literature giving information on the abovementioned branches of stellar astronomy, and thereby reducing their labors in reading up the subject to a minimum.”

Gold Medal of the Royal Astronomical Society.-The gold medal of the Royal Astronomical Society was awarded, in 1876, to M. Leverrier, Director of the Paris Observatory, for his theories of the four great planets, Jupiter, Saturn, Uranus, and Neptune. Leverrier's theoretical investigations of the motions of all the principal planets have now been presented to the Académie des Sciences. His theories of the four inner planets were completed several years since, and for these, it will be remembered, the medal of the society was awarded him in 1868. At the annual meeting in February, 1876, the president, Prof. Adams, reviewed the labors of the distinguished mathematician, upon whom the highest honor of the association had been a second time conferred; explained the grounds on which the council had based their decision; and, in concluding, expressed to M. Leverrier the deep interest with which astronomers had followed him in his unwearied researches, and the admiration which they had felt "for the skill and perseverance by which he had succeeded in binding all the principal planets of our system, from Mercury to Neptune, in the chains of his analysis.”