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The following recorded observations were made in 1861, May 18, 7. 0, the moon's age being 8.87 days.

In the present month, May 1878, the moon's age at noon on the 11th will be 90 days; during the evening of that day, should it be clear, the objects specified below may be observed. A notice of whatever may be

seen if sent to Buckhurst Hill will meet with due attention.

Tycho half in shadow; terminator some little distance from it to the east. Gamicus and Pitatus, both west of the terminator, very distinct. The central mountain in Tycho very magnificent, its shadow touching the base of the interior eastern rim; it then passes through Copernicus, the floor of which is in shadow and the interior of the eastern rim beautifully illuminated. The group Parry, Bonpland and Fra Mauro between Pitatus and Copernicus well brought out, being west of the terminator as well as Le Verrier, Pytheas and Lambert.

The short lateral mountain range on the north-west of Plato has two well defined peaks on the east side casting well defined shadows, the land rises a little on the west, inclosing between it and the east range a somewhat narrow shallow valley which occasions the break in the northwest rim so very frequently observed.

[The Rev. R. S. Hutchings, of Salisbury, observed the two peaks mentioned above in March, 1878, viz., on the 13, 14 and 16, he also observed the western boundary of the crateriform depression north of Plato. W. R. B.]

Western rim interior shadow well marked, irregular with three projecting points corresponding to B. and M.'s 7, 8 and a very distinct. On the south-west the shadow is a mere line inclosing two bright spots which appears as two small mountains within the rim.

South-west exterior. The ravine Z in my key-plan very distinctly marked, the south-west slope of the rim east of the ravine very luminous, indicating its greater altitude. Note.-The sun is shining very obliquely on the highest parts of this ridge. Query, Are the two bright mountains, mentioned above, on the interior ledge or terrace observed at later epochs of illumination?

[Miss Ashley, of Bath, observed the ravine between March 13 and 24, 1878. She says, "there is a sort of ridge or double line of the wall of Plato, beginning just south of the crater G, and going to a point northeast of B. and M.'s y. W. R. B.]

Floor tint a greenish grey. The second of B. and M.'s stripes from the east rim distinct but very faint.

At 8 p.m. of the same evening, May 11, 1878, moon's age 9'33 days, the following objects observed, 1861, March 20, 10. 25, moon's age 9*34, may be seen.

Terminator a little eastward of the eastern edge of Copernicus, which is a very magnificent object and grazing the eastern edge of Clavius. North interior brightly illuminated from the mountain chain on the north-west.

East the rock very brilliant, its shadow being eastward of Plato, and being exceedingly well marked.

South interior well illuminated.

South-west exterior. The ruggedness of the exterior slope well seen with the ravine Z running nearly parallel with the summit. The rock A south-west of Plato very distinct.

North-west. The ruggedness of the exterior slope very distinct, also the rocky, north-west of the crater Plato.

South-west, west and north-west interior in shadow, the shadows

short.

Floor a nearly uniform tint, bluish grey, the dash of blue faint but decided, the colour of the floor darker than that of the Mare Imbrium.

As the observations of the surroundings of Plato in connection with the Selenographical Society are proceeding vigorously, notices of any of the above or any other objects near Plato will be valuable. Buckhurst Hill: April 16, 1878.

Books received.-Ueber Schmidt's Neuen Stern im Schwan. Von Dr. Osw. Lohse. Berlin. 1878.-Popular Astronomy. By S. Newcombe, LL.D., &c., &c. London: Macmillan & Co. 1878.

ASTRONOMICAL REGISTER-Subscriptions received by the Editor.

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The Astronomical Register is intended to appear at the commencement of each month; the Subscription (including Postage to all parts of Great Britain and Ireland) is fixed at Three Shillings per Quarter, payable in advance, by Penny postage stamps or otherwise.

The pages of the Astronomical Register are open to all suitable communications. Letters, Articles for insertion, &c., must be sent to the Rev. J. C. JACKSON, 11, Angel Court, Throgmorton Street, E.C., not later than the 15th of the Month.

The Astronomical Begister.

No. 186.

JUNE.

1878.

ROYAL ASTRONOMICAL SOCIETY.

Session 1878-79.

The Third Meeting of the Session, May 10th, 1878.
Lord Lindsay, M.P., President, in the Chair.
Secretaries-Mr. Glaisher and Mr. Ranyard.

The minutes of the preceding meeting were read and confirmed.
Maxwell Hall, Esq., M.A., Jamaica.

James L. McCance, Esq., Rathfern, Rayner's Road, Putney
Hill, S.W.,

were balloted for and duly elected Fellows of the Society.

Mr. Glaisher announced that 64 presents had been received since the last meeting. Amongst these he drew special attention to several valuable books presented to the Society by Dr. Radford, and also to several volumes of the works of M. Flammarion, which had been presented to the library by the author on his election to the fellowship of the Society.

Mr. Ranyard read a paper by Mr. Waterston On the heat of the stars, after which

The Astronomer-Royal said: I am anxious to express to the Society, partly in consequence of some papers which have appeared in the Monthly Notices, on what might be expected to be seen during the transit of Mercury, and partly in consequence of what has been observed, my opinion on the spots of light which are said to be seen on the disc of Mercury during the transit. The point I wish to call attention to is this: it is my belief that these things are to be looked upon with great suspicion; and I have been led to this conclusion by observations of various kinds, I

VOL. XVI.

cannot say exactly relating to this, but bearing some relation to it; and which lead me strongly to look, in the first instance, to such things as reflection from the various surfaces of the lenses of which the eyepiece is composed, to reflection from the cornea of the eye, and reflection from the tubes of the eyepieces. I may mention a matter that occurred to me a great many years ago. In a room in the Observatory where I was accompanied by my friends (scarcely known to many members of the Society now), Mr. F. Baily and Admiral Smyth, both very accurate men in their way, we were looking out of a western window in the afternoon and admiring the prospect, when Admiral Smyth broke out with, "Why, there is a double star!' Mr. Baily looked at the same place, and said, "Yes, there is a double star." I looked at it, and there I saw it without doubt. I do not know whether they were more satisfied with the evidence than I was, but I thought it incumbent upon me to look a little further, and after a time I found that the origin of this double star was a bright spot on the cornea caused by the sun which was shining at the time. The window through which we were looking was of plate glass, of which the two surfaces were not perfectly parallel, and one gave a reflection which was the cause of one star, and the other gave a reflection which was the cause of the other star. Since then, at the time when there was a controversy concerning the origin of the prominences in solar eclipses, an astronomer came to me and said he had found the prominences and could exhibit them at any time; he showed them to me, and I saw them and scrutinised them a little, and found they were entirely caused by reflections from the interior of the eyepiece tubes. On a third occasion an astronomer reported to me that he had discovered that one of the exterior planets was accompanied by a luminous atmosphere. I warned him to be a little cautious about it, and to examine everything very carefully. I do not think he was quite persuaded by my cautions at first. At last I took it into my own hands, and examined the appearance which he described. I drew the eyepiece out of the tube of the telescope, and put black paper and other papers along the eye tube, and found most indisputably that the appearance of an atmosphere resulted from reflections from the interior of the telescope. After these experiences I need not say that I distrust every observation which speaks of a bright spot on the surface of Mercury. I need scarcely add that in the various successive transits of Mercury at distant times, which, so far as we know, have no relation to its time of rotation, it is exceedingly improbable that the same spot should appear in the centre of the disk during the different transits; and altogether I think I may invite the

Society, when they receive accounts in which are recorded bright spots on the surface of Mercury during the transit, to regard those accounts with a little caution, and put their own interpretation upon them.

He

Mr. Christie said after the remarks of the Astronomer-Royal he must be cautious in bringing forward the observations he was enabled to make of the transit. The observations were made in a very limited time, through the intervals of cloud, and he simply recorded what he saw without trying to explain the causes. saw a minute bright spot in the middle of Mercury, which as far as he could make out did not depend on the motion of his eye. It remained apparently in the same position, but he had no opportunity of testing that point thoroughly. He also saw a ring of light around the planet. It might have been an effect of contrast. It seemed of irregular shape, not altogether circular, and in the interior of the larger ring (which was perhaps half the radius of Mercury in breadth) there was a brighter ring, perhaps a second in breadth, that seemed perfectly circular. The outer ring should perhaps rather be called a halo than anything else. He observed the transit with five different eyepieces, i.e., he used both positive and negative eyepieces in five different ways-first, an.ordinary negative eyepiece with and without a solar diagonal and Barlow lens, and then two forms of polarizing solar eyepiece. The light was consequently viewed after several reflections, from glass surfaces, and he used also a neutral-tint wedge. He could not pretend to have thoroughly investigated the phenomena, as he had only ten minutes at his disposal. Capt. Tupman was also engaged in viewing the transit, and he would read his account of it, which was something a little different from his own. Capt. Tupman reported that he scrutinised the planet with the powers of 110, 140, and 240, but he could not detect any permanent white spot within the disc; there was occasionally a diffused light over the planet's disc, and he could not detect any ring, luminous or shadowy, surrounding the limb; he was struck with the extreme sharpness of the planet's outline, but the clouds made further observations impossible. These observations, Mr. Christie remarked, were directly opposed to his own. There were, however, fourteen other observers within the grounds of the Observatory, and some of them saw the white spot while others did not, and some saw a bright ring and others did not.

The President said: We are favoured this evening with the presence of a distinguished American astronomer, Mr. Rutherfurd, of New York. The meeting will, I am sure, be glad to hear any observations he may have to make on the question raised by the Astronomer-Royal,

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