ably broader than the streak, and, what is very remarkable, portions of blue streak appeared on the north and south sides of the square patch, as though the light patch had been formed from material drawn away from the general covering of the surface, thus leaving vacant spaces both above and below it."

In "The Observatory" for April, 1883, W. F. Denning gives some results of his own observations of Jupiter's equatorial white spot, and also of the great red spot now no longer visible. Mr. Denning has found that while the white spot was completing 2,064 revolutions, the red spot performed only 2,045; in other words, the white spot gained 19 revolutions. The former, therefore, moves 260 miles an bour more rapidly in a direction from west to east around the planet. The average period of the red spot from July, 1881, to March, 1883, was 9 55 37-7; that of the white spot, 9 50 8.7". These results are very nearly identical with those found by Prof. Hough.

Researches on the Saturnian System.-During the past three years Dr. Wilhelm Meyer, of Geneva, has been engaged in an elaborate investigation of the Saturnian system.* His observations of 1881 give the following:

Dimensions of Saturn and its rings for the distance.. 9-5389 Exterior diameter of the bright ring.... 40-35"

Diameter of the ring in the middle of Cassini's division..

84.48 26.05

21-13

11.84

11-80

17.77 16.12

The interior edge of the bright ring was not sharply defined, and hence the interior diameter could not be determined with accuracy.

Orbits of the Satellites and Mass of the Primary.— Dr. Meyer's observations of Mimas and Hype

rion were insufficient for a determination of

their orbits. The others were satisfactorily observed, and the resulting distances and periods are given below:

SATELLITES.

Enceladus..

Tethys..

Dione

Rhea...
Titan

34-3501 18 58 6.92 42 7514 1 21 18 25.62 54 7574 2 17 41 9-29

76 4883 4 12 25 11:57 176 9102 15 22 41 23-16 Iapetus... .514 7103 79 7 49 24-84 The mass of Saturn obtained from these periods is a value somewhat greater than that found by Bessel. The mass of the ring, that of Saturn being 1, is

The Divisions in the Ring. The London "Observatory" for September, 1883, gives the following abstract of Dr. Meyer's researches on the divisions of Saturn's ring, and the disturbing influence of the satellites:

"Prof. Kirkwood showed, some twenty years ago, that Jupiter exercised a peculiar influence

Astr. Nach, Nos. 2,517, 2.527; London Obs., July and September, 1688; Payne's Sid. Mess., September, 1888.

over the minor planets, tending to produce well-marked gaps among them at certain welldefined distances. For if the period of any minor planet were commensurable with that of Jupiter, the latter would exercise a perturbing influence upon it, which would eventually result in a complete change of orbit. Later on, in 1868, Prof. Kirkwood employed the same principle to account for the great division (Cassini's) in Saturn's rings. Maxwell had shown that the rings must be formed of separate particles moving round the planet to a certain extent as independent satellites. But a body moving round Saturn at the distance of Cassini's division would have a period that was very closely commensurable with those of each of the six inner satellites, and it would, therefore, be especially exposed to perturbation. Dr. Meyer has carried the principle yet further, and has investigated every possible combination of the commensurabilities of the revolution periods of the satellites, and he finds that, including the division of Cassini, there are seven places where the satellites would unite to exercise a perturbing influence on the members of the ring system. The first position is where the period would be one fourth of that of Mimas, and marks the inner boundary of the dark ring. Particles moving at almost precisely the same distances would have their times commensurable with each of the other five inner satellites: thus, for a period of one fourth of that of Mimas, we have a distance of 10.56" from the center of Saturn; for one sixth of that of Enceladus, 10-43", and for one eighth of that of Tethys, 10-66". Dr. Meyer sees a consequence of this close agreement in the well-defined character of the inner edge of the the dark ring. One fifth the period of Encedark ring. Next comes Struve's division in ladus corresponds to a distance of 11.79", one satellites give a closely similar result. The seventh that of Tethys, 11-66"; the next three position of Struve's division is not very exactly distance, being the mean between the posiknown, and Dr. Meyer adopts 11-79" as its tions of the inner boundaries of rings C and B. One third of the period of Mimas introduces a new series of commensurabilities in which all the six satellites take part, but the agreement is by no means so close as in the first two cases; and Dr. Meyer regards the indistinct character of the inner boundary of the bright ring B, which would about correspond to the mean of the distances indicated, as connected with this less perfect coincidence. The period of Enceladus is four times, that of Tethys six times, that belonging to a particle at this distance. Cassini's division corresponds, as already stated, to a period commensurable with each of the six inner satellites, the period of Mimas being twice as long, Enceladus three times, Tethys four, Dione six, Rhea nine, Titan thirty-three. The commensurabilities in the case of the four nearest satellites are of the simplest possible character; and we find

that the inner edge of Cassini's division, which is situated at the distance thus indicated, is especially distinctly marked. The outer edge is very indistinct, the influence of Rhea and Titan being much feebler, on account of their great distance.

"One fifth the period of Dione corresponds to about the distance of Encke's division. One eighth of Rhea's period and one half of Titan's approximate roughly to the same distance. The division is faint and ill-defined. One third the period of Tethys, the simplest relation now remaining, indicates the outer boundary of the ring system, and one seventh that of Rhea, and one twenty-sixth that of Titan, correspond to distances of nearly the same amount.

"The only simple relation omitted is that of one fifth the period of Tethys, and this closely corresponds to integral parts of the periods of the three next outer planets. There should, therefore, be another division at about 14-7". Dr. Meyer does not seem aware of the fact; but several observers of Saturn have noticed that ring B begins to shade off a little nearer Saturn than the center of the ring, which would correspond to a distance of about 14.7" or 14.8". Prof. Holden speaks of the point where this shading off begins as 'a definite point.' The correspondence between calculation and observation as to the divisions of Saturn's rings would, therefore, seem to be complete."

At a meeting of the Philosophical Society of Washington, Oct. 13, 1883, William B. Taylor recalled attention to M. Struve's conclusion, announced in 1851, that the rings of Saturn are increasing in breadth, while the interval between the inner bright ring and the planet is gradually decreasing. This conclusion, according to Mr. Taylor, is confirmed by later observations; although the change is probably less rapid than was inferred by Struve, from a comparison of the measures up to 1850. This process of convergence, it was shown, is a necessary consequence of the modern discovery that the rings consist of dense streams of indefinitely small satellites. All parts of the ring are subject to perturbations by the exterior members of the Saturnian system. The bodies composing the ring can not, therefore, revolve in circular orbits. Hence the friction or collision of the different parts must frequently occur, resulting in a degradation of motion," a convergence of orbits, and a shortening of the periods. In this theory of their constitution Mr. Taylor foresees the ultimate precipitation of the rings upon the surface of the planet.

Uranus. The question whether Uranus has any measurable ellipticity seems to have been definitely settled by the recent observations of Profs. Safarik, of Prague; Schiaparelli, of Milan; and Young, of Princeton. The polar compression, according to these astronomers, is about T This is greater than that of Jupiter, and nearly equal to that of Saturn-a fact indicative of a rapid rotation. Prof. Young

has also observed certain spots or markings on the surface of the planet, similar to those on Jupiter and Saturn, by the continued examination of which the rotation period may possibly be determined.

Comets. On the evening of February 23, 1883, a comet was discovered by W. R. Brooks, of Red House Observatory, Phelps, N. Y. The same body was independently detected only a few minutes later on the same evening by Dr. Swift, of the Warner Observatory, Rochester. About the first of March the comet was described as nearly round, and with a very condensed nucleus. According to some observers, it had a granular appearance, somewhat resembling a resolvable nebula. It had a faint tail, about 18' in length. From observations made at Cambridge, Mass., on February 24th, March 5th, and March 17th, and one at Albany, N. Y., on March 5th, Messrs. Chandler and Wendell, of Cambridge, computed the following elements: Perihelion passage = 1888, Feb. 18 9857, G. M. T. Longitude of perihelion... Longitude of ascending node. Inclination...

Perihelion distance

29° 00′ 00′′ 278 7 41 78 4 40 0.7599

On the night of September 1st, W. R. Brooks observed a small object, which he at once suspected to be a comet. Cloudy weather prevented satisfactory observations till the night of the 3d, when his suspicions were fully confirmed. The comet was circular, more than a minute in diameter, had a well-defined starlike nucleus, and was without a tail. From about two weeks' observations at the Dudley Observatory, Albany, N. Y., Prof. Lewis Boss found the elements of the comet's orbit so nearly coincident with those of the comet discovered by Pons on the 20th of July, 1812, as to leave no doubt of their identity. This fact was announced on the evening of September 19th. The sameness of the two bodies, however, had been independently shown one day earlier by the Rev. George M. Searle, of New York. Mr. Searle's conclusion-reached by a method different from that employed by Prof. Boss-was at once forwarded to Harvard College, where it was received on the morning of September 20th. Marked changes of structure in approaching the sun were observed within three weeks from the date of its discovery. Indications of a nucleus were seen at Harvard on the night of September 21st. The next night its appearance was greatly changed; the brightness being nearly equal to that of an eighthmagnitude star. On the night of the 23d it had lost its stellar aspect, had become blurred, had a rather distinct nucleus, and was beginning to develop traces of a tail. The perihelion passage will occur about 1884, January 25th.

Attention has been called to the fact that the elements of this comet strikingly resemble those of De Vico's comet of 1846, with the exception that the ascending node of the one coincides with the descending node of the other. This close coincidence of orbits has been thought to indicate a common origin.

Periodicity of Comets.-At the session of the Paris Academy of Sciences on January 8, 1883, M. Zenger read a paper on the periodicity of comets. The theory proposed includes the following propositions:

1. Comets have originated in the sun. 2. Their origin has been in some way connected with the sun's rotation.

3. Portions of the matter forming the solar protuberances have been thrown out into space by enormous explosive force. From the matter thus ejected large meteorites might gather about them such quantities of the coronal substance as to constitute comets.

4. The periods of comets are multiples of half the rotation period of the sun.

M. Zenger has collected a number of facts which he regards as evidence in favor of his hypothesis.

The Great Comet of 1882, and the Spectroscopic Method of determining Motions in the Line of Sight. -This comet afforded an excellent opportunity for testing the accuracy of the spectroscopic method of finding the rate of approach or recession of the heavenly bodies. M. Thollon, observing the comet's spectrum on September 18th, found the bright lines of sodium displaced by an amount indicating a recession at the rate of forty-seven miles a second. After the comet had been observed for a sufficient length of time to determine its orbit, its true rate of motion in the line of sight was found to have been fortyfive miles a second. As the amount of displacement was only estimated by M. Thollon, not accurately measured, the agreement between the observed and calculated rates is quite satisfactory. The comet's rate of recession, September 18, 1882, was about equal to that of Vega as determined by the spectroscope.

Meteors. The following large meteors were observed during the year ending December 1, 1883 :

On December 12, 1882, a large meteor was seen from the United States steamer Alaska, westward from San Francisco, latitude 38° 21', longitude 134° 7′ west; when about 10° above the horizon it exploded with a loud detonation, the glowing fragments plunging into the

ocean.

At Concord, N. H., one of the largest and most brilliant meteors ever observed there was seen on the afternoon of December 20, 1882, between four and five o'clock. It passed from west to east, and was as plainly visible as meteors usually are after dark.

Payne's "Sidereal Messenger" for March, 1883, contains an account of a very brilliant meteor which passed over Central Indiana on the evening of January 3d. From observations at numerous points in Indiana and Illinois it is concluded that the meteor first became visible over Grant county, Indiana, at a height of about 85 miles, that it passed very nearly over Kokomo and Lafayette, its height at the latter place being 53 miles; that its course was south

78° west, and that the length of its visible track was about 140 miles.

About six o'clock on the evening of February 5th a meteor three or four times as large as Venus was seen at several points in Indiana. At Bloomington, when first noticed, it was a few degrees east of south, 18° or 20° above the horizon. It disappeared behind a building, the length of its visible track having been nearly 20°. At Martinsville, Morgan county, it was first seen 5° west of south at an apparent elevation of 18°.

On the 16th of February a large meteoric stone fell, a little before three o'clock in the afternoon, between Cremona and Brescia, sinking more than three feet into the earth. The explosion was heard at a distance of 12 or 13 miles.

At Norwich, Conn., a meteor of great magnitude was seen on the evening of February 27th. Its path was from the northeast to the northwest.

Early on the morning of March 4th an immense fire-ball darted across the heavens at Petersburg, Va., brilliantly illuminating the city. Its course was northwest, and an explosion was heard shortly after its passage.

At the meeting of the Royal Academy of Vienna, on the 14th of June, 1883, Prof. G. von Niessl read an elaborate discussion of the observations of a meteoric fire-ball seen at Brünn and elsewhere, at about 7 30m on the evening of March 13, 1883. Dr. von Niessl finds the radiant point of this meteor to have been in right ascension 148° 30′ and in south declination 9°. Its mean altitude was about 61 English miles, and its heliocentric velocity was estimated at 50 miles a second. The meteor's orbit about the sun was, therefore, an hyperbola. If it belong, then, to a meteoric cluster, no member of the group can be expected to return. Several other large meteors are known to have appeared at nearly the same epoch.

On the evening of April 14th, at 7h 30m, a remarkably fine meteor was seen at Wooster, O. When first noticed, its direction from the point of observation was east-southeast, about 45° above the horizon. It had at least twice the apparent magnitude of Venus, and the line of its motion would have cut the horizon a little north of east. After a brief visible flight as a single body, it suddenly burst into fragmentstwenty or more-all brilliant and pursuing the same direction, but more slowly, and falling somewhat below the line which the meteor seemed at first to pursue.

At about 10 45m on the evening of June 3d, a meteor whose apparent magnitude was several times that of Venus was seen at several points in England. At Ripon its length of path while visible was about 120°, with the middle point due east; direction of motion, parallel to the horizon; elevation, 20°; length of train, 25°. Another large meteor was seen later in the same evening.

A splendid meteor was seen in the evening

twilight, in England, on the 6th of July, at 8" 50. Its course was from northeast to east, at an altitude of 27° when first seen, and 22° when it disappeared. Its motion was slow; the duration of visibility being six or seven seconds. When first seen, its form was globular, but in a second or two it became elongated as though the change were produced by the resistance of the atmosphere. Its color was at first a deep red, afterward a golden hue, and just before disappearance, a brilliant white.

A meteor of intense brilliance was seen at many points in New Zealand at 446m. P. M., on July 12th. At Ohinitahi it was seen moving slowly from the west in an easterly direction, at an altitude of about 45°. Its appearance was in broad daylight.

A meteoric fire-ball was seen in England at 8h 25m on the evening of August 11th. It moved easterly, and its color was a deep amethyst.

A beautiful meteor, considerably brighter than Venus, was seen in different parts of England about ten o'clock on the evening of August 19th. As seen near London by A. J. Mott, "it passed along the eastern sky and vanished over the summit of the Little Orme. The path was northward, nearly horizontal, apparently much foreshortened, for the motion was very slow-not faster than that of balls falling from a rocket; white light, slightly tinged with blue. The meteor divided, and left one large and several smaller portions behind it, all vanishing together." According to Mr. Mott, the meteor did not reach the earth, but after skimming through the upper atmosphere at an altitude of about seventy miles passed onward in its orbit.

A splendid meteor was seen near London, Eng., about nine o'clock on the evening of October 6th. It passed from the northeast, beneath the pole-star, to the west, where it vanished instantaneously without bursting. The nucleus measured at least five minutes of arc in breadth, and was extremely brilliant.

Meteoric Showers. So far as reported, no meteoric showers of any considerable note occurred during 1883. The numbers seen were small both in January and April; while the showers of August and November almost totally failed. At Great Badow, Eng., H. Corder kept watch on the nights of the 9th, 10th, and 11th of August, with the following results: On the 9th, in two hours and fortyfive minutes, 61 Perseids were counted, or 22 an hour. On the 10th, 113 were seen in two hours. On the 11th he watched the whole night, counting 157 Perseids in five hours; the highest number in an hour being 43. The radiant was in 46° R. A., and 56° N. declination.

Telescopic Meteors.-In March, 1883, W. F. Denning, of Bristol, Eng., observed a number of telescopic meteors of the eighth or ninth magnitude. These, as well as those seen during former observations, were generally remark

able for the slowness of their motion—a fact probably due to their distance.

Double Stars. In the "Sidereal Messenger" for November, 1883, S. W. Burnham has discussed the observations, by himself and others, of the double star Delta Equulei. The principal star of this wide pair is itself an excessively close binary system, the components of which are very nearly equal. Mr. Burnham finds the probable period a little less than eleven years-much shorter than that of any other binary star now known-shorter even than the period of Jupiter. Mr. Burnham remarks that "by reason of the rapid orbital motion of this close pair, and its movement through space, this is undoubtedly the most important and interesting of all the sidereal systems which have been investigated."

On the evening of October 5th, Prof. C. A. Young, of Princeton, discovered the duplicity of a star in right ascension 16h 29m. 26.3", declination N. 58° 00′ 49.9". The components are of magnitudes 8 and 94.

The last report of the Astronomer Royal, W. H. M. Christie, contains some interesting results derived from a discussion of the observations of Sirius from 1877 to 1883. A few years since, the spectroscope indicated a rapid recession of this star in the line of sight. A comparison of observations, however, has led to the conclusion that its rate of departure has progressively diminished during the past six years, and that the motion is now on the point of being converted into one of approach—a fact which seems incapable of any explanation except on the theory of orbital motion.

Parallax of Certain Stars.-Prof. Asaph Hall, Director of the Naval Observatory, Washington, D. C., has recently completed a series of observations for determining the annual parallax, and hence the distance, of Alpha Lyra and 61 Cygni. In his reduction of these observations, Dr. Hall was assisted by Prof. Edgar Frisby. The resulting value of the parallax of the former star is 0.1797", corresponding to a distance more than a million times greater than that of the sun from the earth. The parallax of 61 Cygni was found to be 0.4783", and hence its distance is about 380,000 times that of the sun. This value is very nearly identical with that deduced from a series of Dunsink observations extending over a much longer period. The probable error is small in each determination.

At the session of the Astronomical Congress in Vienna, September 14-16, 1883, Dr. Elkin reported the result of some parallax determinations at the Cape of Good Hope by Mr. Gill and himself; particularly of Sirius and Alpha Centauri. The observers found the annual parallax of the former four tenths of a second, and that of the latter three fourths.

Mean Parallax of Stars of the First Magnitude.— Dr. Gylden, of Stockholm, has been lately engaged in a series of observations for finding the annual parallax of the brightest stars. The reduction has not yet been completed, but Dr.

Gylden has reached the conclusion that the mean parallax of stars of the first inagnitude is about one tenth of a second. With this result, the average distance of these bodies would be two million times greater than that of the sun-a distance requiring more than thirty-one years for the transmission of their light to the earth.

Distribution of the Variable Stars.-In the "Observatory" for June, 1883, T. E. Espin, VicePresident of the Liverpool Astronomical Society, concludes his interesting paper on the distribution of the variable stars. (See "Annual Cyclopædia" for 1882.) The shortest period in his second class of variables is 135 days; the longest, 570. The variation in brightness is from one to nine magnitudes. The number of stars in relation to different periods is as follows:

"Class I. With short periods and small variation.

"Class II. Long period and great variation. "Class III. Period of several years and small variation.

"Class IV. Temporary stars."

The "Monthly Notices of the Royal Astronomical Society " for March, 1883, contains a note by the Rev. T. E. Espin, of Birkenhead, Eng., on the variability of Beta Cygni and 63 Cygni. The former is placed in the table of suspected variables in "Chambers's Astronomy,' and this suspicion has been confirmed by Mr. Espin. The change in brightness is not great about one magnitude while the period, though not well ascertained, is undoubtedly several years. The period of 63 Cygni is about five years, and the observed variation is from the sixth to the 4-7 magnitude.

Dr. Peters's Star-Charts.-Dr. C. H. F. Peters, of Hamilton College, N. Y., has recently published the first installment of a very elaborate series of star-charts. They are to contain all stars down to the 14th magnitude, as far as 30

From his examination of these tables Mr. Espin infers:

1. That the number of stars increases with the length of the period.

2. That the number of stars increases with the variation in magnitude.

3. That more than two thirds of the variable stars of class second vary more than four and less than six and a half magnitudes; and, 4. That nearly two thirds of the variable stars of class second have periods between 320 and 420 days.

Mr. Espin concludes as follows: "When, nearly eighteen months ago, I commenced the first of these papers, I believed that all cases of stellar variation might, with the exception of temporary stars, be included in classes first and second. Lately, however, I have become aware of the existence of a new class-stars which have a small fluctuation in magnitude once in several years. The observations of 63 Cygni first led me to this conclusion, and some of the stars suspected of variation now under observation go far to confirm it. For the greater part of the time the light of these stars is constant, but then it alters a magnitude or so; but, after a month or two, it returns to its ordinary magnitude. Many of the stars suspected of variation undoubtedly belong to this class third, and it is obvious that only long and careful determinations of magnitude during many years can determine the periods and variation of such stars.

"Summing up our results, then, we find four classes of variable stars:

out the whole of the twenty-four hours. Dr. Peters has himself done all of the observing as well as the draughting, and the charts are published at his own expense, for gratuitous distribution. The construction of these charts has occupied his time and attention for the past twenty years. In his laborious observations, he not only carefully marked the place of every one of the 60,000 stars or more already mapped, but, after receiving the proof, he again compared the positions with the actual condition of the heavens, so as to insure the utmost possible accuracy. It has been while engaged in this work that Dr. Peters has picked up so great a number of small planets; these interesting discoveries being merely incidents connected with his systematic observations for another and, perhaps, more important purpose.

Recent Papers on Astronomy.-The following astronomical papers were read at the Minneapolis meeting of the American Association for the Advancement of Science, August, 1883:

1. The Total Solar Eclipse of May 6, 1883; by Prof. E. S. Holden.

2. Internal Contacts in Transits of Inferior Plan

ets; by Prof. J. R. Eastman.

3. Physical Phenomena on the Planet Jupiter; by Prof. G. W. Hough.

4. Observations of the Total Solar Eclipse of May 6, 1888; by Dr. J. Janssen.

5. Orbit of the Great Comet of 1882; by Prof. Edgar Frisby. 6. Some Observations on Uranus; by Prof. C. A. Young. 7. Observations on the Transit of Venus made at Columbia College, New York city; by Mr. J. K. Rees.

Astronomical Prizes.-At the annual meeting of the Royal Astronomical Society, Feb. 9, 1883, the society's gold medal was awarded to Dr. B. A. Gould, Director of the Observatory at Córdoba, South America. "The work for