noticed that in small instruments the determination of the Nadir point on opposite sides of the circle will differ, but that with the Greenwich circle this does not happen. The fact is, the temperature of the observer's body does not affect the large telescope. The author therefore proposed as large a telescope as is compatible with portability. This transit has a 5-inch object-glass and 5-foot focal length, which is shorter in proportion than any before attempted. The adjustments which have been shown and described are not absolutely new, though the combination may be. In fixed instruments in Observatories, the axis is brought into position by the filing and scraping of the engineer; but in travelling we cannot take such a person with us, and the adjustment has hitherto been made by a slide. In this case there will either be looseness or a strain. The pieces which carry the bearings of the pivots are parts of spheres moving in spherical cups. As to the levelling, we want to know, not the position of the axis, but of the optical centre of the axis of the telescope. Masses of metal are liable at every instant to change their form. The tube and axis may have different flexures at different elevations. The idea of the mode of levelling is due to Mr. Cooke. There are four levels attached to the central cube; they are suspended on pivots, which can be rotated and reversed, so that the instrument cannot undergo unsymmetrical change without detection. At Greenwich, levelling is dispensed with, reflection from mercury being used for this adjustment; but this mode can only be adopted when the collimation is performed by two fixed telescopes, as at that Observatory. It is doubtful whether collimators could be worked in the field, and it is therefore proposed to collimate by reflection from mercury, and level in the way described, although the central cube is perforated to admit of employing collimating telescopes if desired.

The Society then adjourned for the summer recess.

CORRESPONDENCE.

N.B. We do not hold ourselves answerable for any opinions expressed by our correspondents.

DOUBLE STAR NEAR ARCTURUS.

TO THE EDITOR OF THE ASTRONOMICAL REGISTER. Sir, I have lately noticed near Arcturus a pretty double star, which is not mentioned in Webb's Celestial Objects nor in Darby's Handbook, and is not marked in the last edition (by Dayman) of the smaller maps of the S. D. U. K. It is also, I presume, not included in Smyth's Cycle, as these

maps are said to contain every object in that delightful but, unfortunately, almost unattainable book. It is situated, with reference to Arcturus, about 1° N., and a little f. Mags. about 7 and 9; position about 180°; and distance +4"-by estimation merely, as I have no micrometer. The strong twilight has not been favourable for judging of colour, but to my eye the components appear pale orange and faint blue.

Doubtless this object is well known to astronomers, but to many amateurs it may be new, as it has been to me; and as it is easily found, and well suited to small telescopes, you may perhaps think it worth while to allow this communication to appear in the Astronomical Register.

If any of your readers who may be possessed of the means of reference will inform me where this elegant little pair is catalogued, and would correct my rough guesses at its position and distance, I should be very much obliged.

I first noticed it with a power of 73 on a 44 object-glass by Cooke.
I am, Sir, yours faithfully,

June 12, 1866.

R. C. H.

PARASELENE-COMETS, &c.

TO THE EDITOR OF THE ASTRONOMICAL REGISTER. Sir,-Allow me to offer a few remarks on three points noticed in your June number. First, -It is not unlikely that Mr. Barkas witnessed a portion of a "Paraselene." Second,-It appears that " A Norrible Tail" was not long enough to reach a paragraph in a eurious book entitled Cometomantia, published in 1684, by an anonymous author, who dedicates the work to "Seth Lord Bishop of Salisbury," and signs himself his "dutifull son and obedient servant." The copy from which I make the following extract bears the arms of the late Sir George Shuckburgh, Bart., and has on the fly-leaf facing the title this inscription, "By Boyle." On page 40, the author thus writes:-"It was soon seen that this thrusting and shoving of sunbeams was a very precarious notion; and therefore the most judicious astronomers go another way to work. They abandon their opinion who think the tail belongs to the substance of the comet, and is a flame issuing from it; and instead of that they defend this for truth, that the tail or beard is no other than the beams of the sun transmitted through the diaphanous head of the comet. This is embraced by Cardan, Longomontanus, Scaliger, and that famous triumvirate of astronomers, Tycho, Kepler, Galilæus. If these say true, the transparent body of the comet is illuminated by the solar rays, and the sun thus shining through it and causing a various refraction and repercussion of light, makes that splendour which we call the tail or tresses of a comet. In order to this, they fancy the body of the comet to be like a globe or ball of glass, which by its diaphanousness imbibes the beams received from the sun, and those beams passing through it appear on the reverse of it. Such a kind of trajection or striking of the sun's rays through the head or body of a comet is the cause of its beard or tail. But this will not clear the point, for then the tail should not be of that figure it appears, but of a Comick one, as the rays appear behind a glass ball, viz., broad towards the glass, but narrower and sharper the other way. * * * Thus the laws of Opticks and the Rules of Perspective will be endangered if we tie ourselves to this hypothesis.

"Say that by the transparency of the head of the comet the sun's rays

are transmitted, and so the train is in a fair way to be made, yet there is required moreover an opacity to receive and turn back those rays to our eyes, that we may see them. This is done, if Tycho Brache's saying so will suffice. The rays of the sun (saith he) passing through the comet's head, meet with some matter in the Ethereal region which is darkish, and so reflects them back to us. Thus the blazing stream is produced. But this supposes thick and opake matter in the Æther, which ever before passed for Pure, Subtile, and Perspicuous."

Third, Sir John Herschel's Outlines of Astronomy, fourth edition, page 249, foot-note, says :-"The actual illumination of the lunar surface is not much superior to that of weathered sandstone rock in full sunshine. I have frequently compared the moon setting behind the grey perpendicular façade of the Table Mountain, illuminated by the sun just risen in the opposite quarter of the horizon, when it has been scarcely distinguishable in brightness from the rock in contact with it. The sun and moon being at equal altitudes, and the atmosphere perfectly free from cloud or vapour, its effect is alike on both luminaries."

The above extracts will show-first, that the idea broached by Mr. Lawrence is by no means new. Second, that the reflection from the moon's surface is very similar to that from the earth's. Its intense brightness, alluded to by J. W. Thomas, appears to arise from its being seen against a dark sky. If a small piece of paper be illuminated by a single ray of light from a lamp in a perfectly dark room, when none of the objects contained in it are visible, the paper will shine with much greater brilliancy than in ordinary daylight. Sir John Herschel's observation bears greatly on the nature of the lunar surface.

I am, Sir, your obedient servant,

42 Sewardstone Road West,

Victoria Park, London, N.E.: June 2, 1866.

W. R. BIRT.

LUNAR PHENOMENON.

TO THE EDITOR OF THE ASTRONOMICAL REGISTER. Sir,-Being in a railway train, between Berwick and Newcastle-uponTyne, on the night of the 2nd to the 3rd of May last, I saw the curious "lunar phenomenon" described in the last (42nd) number of the Astronomical Register, as seen by your correspondent, Mr. T. P. Barkas, at Newcastleupon-Tyne. The following was my rough note of its appearance :

"1866, May 3rd, 1h. A.M.-Shipton, N.B.-A remarkably straight vertical pillar of light through the moon,-three degrees in length above and below, of the same width as the moon. Thin cirrostratus cloud over all the sky." There were neither halo, horizontal beam, nor mock-moons seen near the moon, as in a lunar phenomenon of the same kind described by Hevelius, and figured in Lowe's Treatise on Atmospheric Phenomena, at p. 63. A vertical bar through the sun is figured at p. 35 of the B. A. Report for 1864, which projected in front of a dense bank of clouds near the horizon, to a distance at least equal to the apparent diameter of the sun. From this circumstance, the "vertical pillar" is probably the effect of a sort of mirage of the kind supposed by Mr. Barkas. I have also noticed that it is commonly seen only at low altitudes of the sun and moon. I am, Sir, your obedient servant,

Collingwood, Hawkshurst:

ALEXANDER S. HERSCHEL.

June 2, 1866.

THE MINOR PLANETS.

TO THE EDITOR OF THE ASTRONOMICAL REGISTER. Sir,-To judge by some of the names applied of late years to newlydiscovered minor planets, the discoverers are rather hard up for appropriate designations. Under these circumstances, I have ventured to draw up the following list of classical names at present unappropriated, in the hope that they and others similar may be taken up before we are presented with any more barbarisms like Angelina, Maximiliana, &c. Female classic names are undoubtedly the best, but no complaint need be raised against reasonable geographical names, such as Parthenope.

My list is as follows:

TO THE EDITOR OF THE ASTRONOMICAL REGISTER. Sir,-Having several years ago fancied that the position and markings of cirri assist in predicting the probable wind of the next day or two, I have amused myself, when opportunity served, by verifying my theory. Although the subject of Clouds and Winds does not, strictly speaking, suit the pages of an Astronomical periodical, yet, on the Nihil humani alienum principle, it may claim to be admitted alongside of Fireballs and similar meteoric phenomena. Indeed, it is an old remark, that the path of a shooting star indicates the quarter from which the wind may be expected. This may hold good once in three or four times, but it is difficult to imagine the coincidence to be more than accidental. It is different, however, as I apprehend, in the case of cirri, which I consider as due to electrical action bringing into sudden visibility the diluted vapours of the upper atmosphere, the filamentary fringes forming a quasi electroscope of a huge revolving cylinder of from 10,000 to 100,000 cubic miles of air.

That the solar heat with its resulting tropical and polar currents are sufficient to account for the rotation, no one can doubt; and it is perhaps equally certain that the friction of this cylinder must develope a large amount of electricity, and that its excess will exhibit itself in the diverged projection of those cirri, sometimes in the form of huge feathers, sometimes of palm trees with several years' successive foliage springing simultaneously from an imaginary trunk, and at other times like the arrows of the "far-shooting Apollo" hurtling in mid-heaven.

This revolving cylinder is perhaps seldom quite perpendicular to the surface of the earth. Indeed, the different velocity of translation of its upper and under discs, due to the earth's rotation, would alone cause it to assume an oblique position, independently of the momentum communicated by the downward polar current. This latter current may account for the rotation of cyclones in the N. hemisphere being contrary

to the motion of the hands of a watch; for, coming from the N. and E., the polar current must impinge first on the northern side of the cylinder, passing off on its NW. surface, and so giving it a motion from right to left, or retrograde. Similarly (mutatis mutandis), in the Southern hemisphere, the SE. polar current will cause the cylinder to rotate with the hands of a watch, or from left to right. The effect in both cases is aided by the SW. and NW. equatorial currents.

But to return to the cirri and their pre-indications. In all cases I regard the point or axis of convergence to show, first, the point towards which the cylinder rotates-that is, its tangential direction, as referred to the horizon; and, secondly, the point from which, as the cylinder revolves, we may expect its surface sweep to manifest itself, or produce what we denominate a gale.

The observer must be on the alert to localise these phases, as they often disappear in less than half an hour.

If these jottings be true, then every man may be ready to hoist his own storm-drum.

Portadown, Ireland:
May 7, 1866.

I am, yours obediently,

T. B.

LUNAR CRATERS.

TO THE EDITOR OF THE ASTRONOMICAL REGISTER. Sir,-In your number for November 1865, pp. 262 and 263, you did me the favour of inserting a table of Lunar Craters on and near the Mare Crisium. On the 4th of November 1865, my friend Mr. Knott added considerably to the number then recorded; and in preparing my Report to the British Association for the Advancement of Science for press, I included all at present known. On referring to Schröter's Records, I found figured in T. lxvii. fig. 13 of his Seleno-topographische Fragmente, a pair y and 8, near the W. border, which had not been detected either by Mr. Dawes, Mr. Knott, or myself, in our observations between 1862 and 1865. On the 19th of March 1866, I was gratified by seeing, exactly as figured, Schröter's pair apparently in the position of Beer and Mädler's group of mountains marked A. On the 18th of April I again saw them quite as readily as on the 19th of March, and I had the further pleasure of finding them on the 17th of May; and in addition, the little crater at the N. foot on the W. side of the mountain, on the border of the Mare Crisium, marked ẞ by B. & M., which is marked e in Schröter's figure. The three craters are absent on B. & M.'s map, and I suspect they never saw them, as it is not unlikely that changes of libration may conceal them from view. The pair has not yet been registered, as Mr. Dawes' ƒ 1c 72 lies near the locality. Schröter's was registered as IC 75. Probably some of your lunar observers may be able to determine if the pair be near ICT2. There are several craters on the NW. border that at present are neither symbolised nor registered. I append the continuation of the table, and remain, Sir, Your obedient servant,

Victoria Observatory, 42 Sewardstone Road West,

Victoria Park, London, N.E.: May 18, 1866.

W. R. BIRT,