only were seen. The broad one, lying a little south of the equator, had no longer its sides parallel, as on the 28th of January, but a deep hollow on its southern edge, reaching nearly across on the preceding side. The principal northern belt was much broken and diversified with dark spots and inequalities. But the most remarkable feature was a curdling appearance of the whole intervals between the belts, and also of the entire region about the south pole.

"On the morning of the 2d of February, we had a good view of nebulæ Herschel Nos. 1357 and 1376. Sir John Herschel's drawings, given in the Philosophical Transactions of 1833, are faithful representations of the wonderful phenomenon which they present. The great nebula in Andromeda shows a similar structure, but on a much larger scale. A fourth, which we find to possess the same peculiarity, is h 859, A. R. 11h 11m, Dec. +14° 30'; it resembles h 1357, but is fainter.

เ

"We find the great nebula of Orion to be connected with those about C and Orionis. Sir John Herschel's No. 75 in his Cape Catalogue of the stars in the nebula of Orion, which has heretofore been recorded as a single star of the eighteenth magnitude, is a double star. The direction of a line joining the components passes near 1; the distance is estimated at two seconds. No. 91 of the same catalogue has been hitherto taken for a single star of the seventeenth magnitude. This likewise is double, and the direction towards ' of the Trapezium, and the distance estimated at two seconds. The following one of this pair is as precisely as possible on the following edge of the bright part of the nebula, at the bottom of the Sinus Magnus."

A communication was read from Mr. G. P. Bond, respecting the great nebula in Andromeda; the object of which was to direct the attention of astronomers to a remarkable peculiarity in its structure, which appears to have hitherto escaped notice. The paper was accompanied by a drawing, taken from repeated examination with the twenty-three-foot refractor of the Cambridge Observatory. Among the results of the employment of increased optical power upon this nebula has been the union with it of several neighbouring nebulæ, which have hitherto been regarded as distinct bodies. This paper was referred for detailed publication in the current volume of the Memoirs.

Mr. Bond communicated a farther notice respecting the third satellite of Jupiter, as follows:

"In my communication of the 5th of February, I gave some account of a remarkable change which took place in the appearance of the third satellite of Jupiter, while transiting his disk on the evening of January 28th. I am now enabled, from subsequent observation, to confirm in a more detailed manner the account then given.

"During the evening of March 11th, this satellite was again seen as a black spot upon the disk of the primary; but as several visitors were present at the Observatory, the observations were discontinued. It was remarked, however, that the spot was of less magnitude than the shadow which subsequently passed the disk.

"On the 18th of March, we were more fortunate. The state of the atmosphere proving favorable, I watched, with my son, the entire transit. The following are the results of our observations.

"At 8h 15m sidereal time of the Observatory, we commenced, by estimating independently the relative order of brightness of the satellites; it was, first, third, second, fourth.

"The third satellite, when close to the limb of Jupiter, suffered no diminution of its brightness or apparent magnitude.

"At the first contact with the primary, the latter seemed to recede from the satellite.

"At 8h 51m, the contact of the centre of the satellite with the limb of Jupiter took place.

"8h. 55. First internal contact; the satellite was then seen distinctly on the disk, brighter than Jupiter, although it had entered on a bright channel between the great belt and a smaller one south of it. The satellite was thought to be less bright on its southern limb.

"At 9h. 15m, it had decreased in brightness so as to become hardly perceptible.

"At 9h 18m. 15, my son, who was now observing, exclaimed quickly, 'The dark spot is coming on; I now see the satellite; the dark spot is on the right hand, perhaps a little above!' On examination, I found the spot was quite distinct.

"9h. 21m.. The dark spot increases, and is now seen on the satellite. 9h. 33m. The spot has become conspicuous.

"At 9h 40m, the diameter of it was measured with the spider-line micrometer, in the direction of the belts of Jupiter, and was found to be 0."50 by B, immediately after the angle of position of what was considered to be the longer axis

170°.

"The following diameters were then measured in the first position :

"10 5m. It appears perfectly black and nearly round; tried different powers; it is best seen with 400; there are doubts of the spot being round, but could not decide on any other form.

10h. 32m. B, thinks it is not so black as it was.

"10 35.

nel.

Satellite past the middle, and keeps in the bright chan

11h 7m. The satellite now appears black; it has accomplished three quarters of its journey across the disk.

"11h 17m.. Spot dark as ever, perhaps darker. B2 thinks it inclines to the south-following limb of the satellite.

"11h 37m. The satellite is seen broad, but not so dark; it is getting near the edge.

"11h 52m.. Can just discern the spot, but the altitude is getting low; however, the seeing is remarkably good, at times, for so low an altitude. It is now doubtful whether the bright part of the satellite can be seen or not.

"11h. 58m. Neither spot nor satellite is visible, absolutely.

“12h. 6m.. One half the satellite is seen as it passes off the disk; it is bright.

12h. 12m.

The last external contact was observed by B, who noticed that the limb of Jupiter appeared flattened.

66 12h 21m.. The third satellite is now seen at a considerable distance from Jupiter, and the order of brightness is, first, second, third. The fourth satellite is under eclipse.

"It is evident that the third satellite is not now one half the brightness of the second, which it far surpassed before the transit took place.

It has also diminished in apparent magnitude, and the light has changed from a strong yellowish-white to a dull bluish-gray color.

"The tabular order of the mean relative magnitudes of the satellites is, third, fourth, first, second.

"One of the most remarkable features attending the progress of this phenomenon was the rapidity with which the change from bright to dark took place. At 9h 15m there was no indication of change, unless the apparent gradual fading of the light of the satellite is so considered, but which I should rather attribute to the increased amount of light reflected from Jupiter nearer this centre. At 9h 18m. 30, when I again saw the satellite, the dark part had so increased as not to be mistaken for a moment, and my son represents the change as taking place almost instantaneously, not leaving a doubt from the first.

"The satellite was watched for some time after the transit, and it appeared to be gradually resuming its pristine brilliancy."

Mr. Mitchell read the subjoined account of a remarkable meteor, which was seen from Nantucket, on the 6th of March last.

"On the 7th of last month (March), 1848, while in Boston, I received a letter from my daughter, at Nantucket, stating that on the previous morning, at about half past two o'clock, a meteor of surpassing magnitude and brilliancy was seen by several persons, and its report was so loud that many individuals were awakened by it. With a view of eliciting information from other quarters, I requested the editor of the Evening Transcript to giye publicity to the fact, simply as I have now stated it.

"On returning to Nantucket, so much was said of the magnitude and extreme brightness of the meteor, and of the loudness of the report, that I was induced to make a systematic investigation of the circumstances attending it, in view of the possibility that some of the fragments, or the undivided body itself, might have fallen upon the island.

"Among the witnesses of the phenomenon were two of the street watchmen, both intelligent men, who were situated, at the moment, 3,250 feet asunder, and in a direction from each other nearly at right. angles with the direction of the meteor as first seen. With each of these gentlemen I went to the spot which they respectively occupied when they first saw it, and by the aid of buildings in the vicinity I

was able to ascertain, to tolerable satisfaction, the apparent direction of its motion, and its position when earliest seen. Taking afterwards, by means of a circumferenter, the difference of its apparent position at these extreme points, and assuming that the eyes of both observers were directed to it at the same moment, which is the more likely to be true, from the fact, that they were both facing the region occupied by the meteor, I found its parallax with this base to be 60; its direction from one being south 5210 east, and from the other south 461° east, each at an estimated altitude of 30°.

"The report occurred ninety-two seconds after the entire extinction of the illumination, and after the meteor, without any appearance of separation, had reached the horizon.

"To obtain the measurement of this interval, I requested each watchman separately, and without the knowledge of the other, to move onward in his usual pace to the position at which he had arrived when the report was heard, and during this period, I noted the time by a chronometer; and it is certainly remarkable, that by this rude method. they differed from each other less than five seconds.

"All parties agree that the illumination was quite equal to that of a bright moon, giving to every visible object a frightful aspect; and also that the brilliancy of the meteor was extremely painful to the eye. Only two persons with whom I have conversed were so situated as to follow its course quite to the horizon, or near to the point of its contact with the earth. Those individuals testify, that it emitted no scintillations, but maintained a perfectly circular form through its whole course. The report is said to have been startling; the rattling of windows and jarring of the houses are spoken of by many witnesses, every one noticing that, unlike the discharge of cannon or a peal of thunder, it was without reverberation. Some persons who were roused by the extreme light, but did not see the illumination, supposed it to have been the jar of an earthquake.

"Observers differ widely in estimating its apparent diameter, though they were requested to observe the moon as the standard of measure. ment. Some supposed it exceeded the moon; others, and quite the greatest number, thought it less than the moon in apparent diameter, the lowest estimate being two thirds the disk of that luminary. I take twenty minutes to be the optical apparent diameter of the meteor; stripping this of all possible illusion arising from its dazzling brightness, I am persuaded that it subtended an angle of at least twelve minutes.