May 23, 1511. The Pope went to Rome June 27. In July he succeeded in forming a secret league with England, Spain and Venice to attack France. On the 17th of August the Pope was taken seriously ill, became unconscious on the 21st, and recovered consciousness on the 22d. On the 1st of September the schismatic council of Pisa was organized. The Crema stones fell into the French territory September 4th. The league between Spain, Venice and the Pope was published October 5th, and in November England, and subsequently MAXIMILIAN, joined the League. For a time success was with the French. On the 11th of April, 1512, the battle of Ra venna was lost by the papal forces and the Roman territory was seriously threatened. But, in spite of such temporary success, the French were forced to withdraw in June altogether from Milan and northern Italy. What would be more natural to RAPHAEL, under such circumstances, than to unite, in the altarpiece that he was painting, the fireball with the rainbow, in order to symbolize at once Divine reconciliation and assistance?

So far as I know no specimens of the Crema aerolites have been preserved. The accounts say nothing about the direction of motion of the fireball. It seems more probable, however, that the motion was from the south or west than from the north or east. The earth's quit was then about S. 35° W., 15° or 20° high. I have elsewhere shown that aerolites in general follow the earth in its orbit, and this makes a motion of this stone from the S. or W. quite probable. If it was moving from the east of south it would be more strikingly visible in Rome, and its appearance in RAPHAEL'S painting may be due to a brilliant course across the Roman skies.

ON THE SIMILARITY OF CERTAIN ORBITS IN THE ZONE OF ASTEROIDS.

By Professor DANIEL KIRKWOOD, LL. D.

[SECOND PAPER.]

In the Publications of the Astronomical Society of the Pacific, No. 7, March, 1890, the present writer named three pairs of minor planets whose orbits are characterized by remarkable similarity. Those given were selected from a larger number, so that only the most marked might first receive the attention of astronomers.

Further study has but strengthened the writer's opinion in regard to the origin of such relations in perturbative action, and the subject is now resumed in the table below:

Groups of Asteroids.

NOTE.-a represents the mean distance, e, the eccentricity, i, the inclination, , the longitude of the perihelion, and , the longitude of the ascending node.

Besides the similarity of orbits given in my former paper, I had, in 1887, specified several others, and in the Annuaire for 1891, M. TISSERAND has independently pointed out three cases of decided correspondence. Twenty-four asteroids are included in the foregoing table, and the number will probably increase with future discoveries.

*The Asteroids, p. 48.

2.7376 0.0588

313

42 51

348 37

2.7379 0.1335

6 56

46 38

325 26

2.7575 0.1331

7 50

199 52

62 28

2.7669 0.1433

335

152 47

64 26

2.7673 0.0763

10 37

149 38

So 47

The explanation of these facts was referred by the writer to the sun's divellent force.† The disturbing influence of Jupiter, however, may alone have been sufficient. The mean density of the solar

nebula when its radius was 300,000,000 miles was

I

340,000,000,

the

present mean density of the sun being unity. The surface attraction of a primitive or nebulous asteriod was therefore almost nil. No exact calculations seem necessary to show that the separated masses might have been dismembered by the unequal attraction of Jupiter on the different parts. In other words, this influence was sufficient not only to detach the matter of asteroids from the central body, but also to subdivide the newly-formed nebulous planets until the fragments finally resulted in the existing asteroids. Evidence is not wanting of the actual occurrence of such division in the case of comets.‡

astronomers.

The study is not unworthy the careful attention of

ASTRONOMICAL OBSERVATIONS.

Made by TORVALD KÖHL at Odder, Denmark, in the year 1890.

Although the following notes do not claim any importance in regard to the progress of Astronomy, I yet venture to publish these few contributions to our astronomical knowledge in the hope that they, perhaps, will be of some interest to the members of the A. S. P.

January 21, 101 A. M. (Time of Copenhagen): A group of sunspots consisting of three larger and some smaller spots is situated near the western limb of the sun's disc.

February 9, 7-91 P. M.: The Zodiacal light appears pretty plain. Northern limb: 347°+3°, 357° +6°, 7°+9°, 14°+12°, 21° 14°, 28° 17°.

Southern limb: 7°+ 19°, 11°+9°, 13°+0°, 20° +6°, 32° 13°. +

At 8h the star ẞ Ceti was seen in the southern limb. The summit of the Zodiacal light seems to reach the middle of Aries.

Corresponding observations had been projected between Dorset, England, and Odder, Denmark, but the cloudy weather did not favor the undertaking. Nevertheless the Rev. S. J. JOHNSON, M. A.,

* The Asteroids, p. 48.

† See the Annuaire for 1891, p. 301. Compare also the elements of the comets of 1668, 1843, 1880, and 1882.

F. R. A. S., in Dorset, succeeded in making good observations on the 7th, 8th, 9th, 10th, 11th and 17th of February, but on the 9th he has only the following remarks:

"Well seen to-night. I could not perceive any red tint such as has often been mentioned. But it was inferior to the Milky Way, inasmuch as it had none of the milky whiteness of the latter."

On

February 23, March 2 and 3: The sun without any spots. the last day a little facula (German: "Fackel") was seen near the eastern limb.

h

March 9, 42" P. M.: A little group of three sun-spots is situated in the northwestern part of the sun's disc.

March 15, April 1, 3, 4, 5, 6, 7, 8, 9, 14, 20, 27: The sun had no spots on its surface.

April 29, 51 P. M.: A group of more than fifteen sun-spots is situated in a south heliographic latitude.

April 30, 8h A. M. and 3 P. M.: The group is now a little more contracted on two places.

111

At 8 30 P. M.: One hour past sunset the planet Mercury is plainly seen with the naked eye about three degrees northwards from Venus near the horizon in the northwestern sky. Then the planets were observed by aid of the telescope and drawings were made (3-inch telescope, power 168).

May 2, 3, 4: No sun-spots visible.

h

May 13, 3 P. M.: In the south part of the sun's surface two spots were perceived.

May 15, 16: No sun-spots.

May 18, 8 A. M.: A group consisting of three sun-spots is situated on the southern hemisphere.

May 19, 8h A. M.:

The sun-spot has grown less.

May 20, 4" P. M.:

The sun-spot near the sun's limb is exceedingly

faint.

May 22, 23, 31, June 1: No sun-spots.

June 8, 8 A. M.: A little sun-spot is situated near the southwestern limb.

June 9, 9 A. M.: In the place where the spot should be situated, only an exceedingly small black point is now visible, but surrounded with very bright faculæ.

June 10, 12, 14, 15, 16: No sun-spots visible.

June 17: The partial solar eclipse. In spite of the cloudy weather, I succeeded in getting a series of drawings of this beautiful

phenomenon, which took place here from 9h 30m to 11h 37m A. M. When the eclipse had reached its maximum, 0.36 of the sun's diameter was covered by the moon. In order to make the eclipse visible to several spectators, the image of the sun was enlarged to the size of one foot in diameter and projected upon a plate of white paper behind. the telescope, and thus a number of visitors (about seventy) could witness the interesting sight.

July 5, 8 A. M.: A group of small sun-spots is seen at the eastern limb.

July 7, 8 A. M.: A group of three larger and several little spots westwards are visible.

July 9, 8 A. M.: The group has still not changed very much in general characteristics, but a new circular spot has appeared westwards near the group, and this very dark spot consists apparently only of the umbra and seems to be quite without any penumbra and is so distinct and limited that it has great likeness to a planet (as Mercury) on the sun's disc.

July 10, 72 A. M.: While the first group has decreased, the mentioned circular spot has grown larger and has been provided with a narrow penumbra, and in the neighborhood five faint black points are visible, but already at 111⁄2" A. M. these points have contracted and formed a greater spot.

July 11, 8h A. M.: The group has not changed very much since the foregoing day.

July 12, 7 A. M.: The former chief group is now disappearing, but near the circular spot two smaller spots are visible.

h

July 13, 7 A. M.: No great change has taken place in the group of sun-spots.

July 16, 8 A. M.: No spots. A large facula is situated near the

western limb.

July 17, 21 P. M.: The sun without spots and faculæ.

August 8, 9: No spots. Facula at the northwestern limb.