scend the ether in these qualities in even a greater degree than that excels ponderable matter with respect to them—that is, succinctly, that pure solar matter is still more transcendently and intensely solid and elastic because its particles are in still more transcendent activity. This inference is considered to harmonise with the obvious peculiarity of the sun, that in it alone, of all the bodies and localities of the solar system, enormous force of gravity and an immeasurable intensity of heat are united.

In the recorded facts of telescopic observation the author finds an “entire absence of evidence or indication that anything exists in the sensible universe which is of greater antiquity than the stars, or prior to them in its origin ;" which, "considered together with the primary induction from the uniqueness and peculiarity of their position and functions as suns," is regarded as tending strongly "to prove that, as a class, the stars are the most ancient objects in the creation, and also (each in its own sphere of action) the origins of the series of physical agencies and processes by which the planets and other classes of heavenly bodies were finally produced and are maintained.” *

This being admitted, it follows that the original production of ponderable matter takes place in the stars, and in our sun as one of them—a conception to which the author had been led by the preceding and other considerations long before the application of prismatic chemistry to the sun.

The energy set free in the condensation within the sun, of the highest imponderable matter essential to it into ponderable matter (an expression which is shown not to be a solecism), and eventually into the metallic vapours which the observations of Kirchhoff and other spectroscopists have discovered in the sun and other stars, is inferred by the author to be at once the exclusive proximate source of the heat and light and other energies of the sun, and (in our solar system) the only and universal origin of ponderable or ordinary matter, the absolute synthesis of which from its imponderable elements is thus believed to take place in the sun.

It will follow that the distribution of heat in the sun, as already inferred by the author,† is from within to without, in the order * Syllabus of Lectures on Astronomical Physics; Lecture VIII. † Companion to the Almanac for 1864, p. 51.

of decreasing intensity-an inference which he conceives to be not contradicted, but supported, by the apparently inferior calorific and luminous condition of the sun's nucleus, as disclosed in the true nuclei or inner umbræ of the spots, compared to that of every other visible part of the sun, and especially of the photosphere, because the exterior regions of the sun are composed entirely of that order of matter-ponderable matter, such as that of which the planets consist-which is alone capable of communicating to the ether of space those vibrations which we know as heat and light.

To be continued.

ASTRONOMICAL WORKS.-Perhaps some, like myself, not in the way of seeing many books, may be glad to have brought to their notice a work, doubtless well known to many, but with which I have only recently become acquainted-Grant's History of Physical Astronomy. I had often seen it referred to, but had no idea, till I read it, of the amount of interesting matter it contains. It should be found in every astronomer's library.

I observe noticed in the Athenæum of June 10, in favourable terms, La Pluralité des Mondes Habités, by Camille Flammarion. (Paris, Didier & Cie.) The reviewer says "This is the second edition of a work which has excited the attention of our neighbours, and worthily. We should like to see it translated." G. J. W.

AIRY'S LECTURES.-A new edition of this well-known manual is in the press, and will shortly be published by Macmillan & Co. We trust that it will be better printed than previous editions.

NEW CELESTIAL ATLAS-An important work has just made its appearance at Paris (Gauthier-Villars, publisher), entitled, Atlas Céleste, contenant plus de 100,000 étoiles et nébuleuses, d'après les Catalogues les plus exacts des astronomes français et étrangers, par Ch. Dien (avec une introduction par M. Babinet). It has occupied 30 years in its preparation, and contains 30 celestial charts, calculated, designed, and engraved by the author himself. The mythological figures of the constellations are excluded-a matter which is to be regretted, because an outline of each would have facilitated reference. The projection of the charts is the development of a sphere 65 centimètres in diametera size which is adequate, yet not unmanageable. By the division of the charts, the surface presents a network of degrees sufficiently extended to receive, without confusion, all stars down to the 9th magnitude, as well as double and multiple stars and nebulæ and clusters. The stars are reduced to the epoch of January 1, 1860, and are placed on the copper-plates with scrupulous exactitude. The stars inserted include also the known variables; and prefixed to the work is a comprehensive catalogue of these objects. M. Dien has been assisted in his labours by MM. Le Verrier et Faye, and the finished result may be pronounced a most important addition to astronomical lite

rature.

ROYAL ASTRONOMICAL SOCIETY.

Eighth Meeting-June 9, 1865.

Warren De la Rue, Esq., President, in the Chair. Secretaries:-Rev. C. Pritchard and R. Hodgson, Esq. Among the presents, of which 37 were announced, the attention of the Society was directed to four as worthy of comment: 1st, A translation of Gauss's Theoria, from Latin into German; 2, A work by Mr. Todhunter, on the History of the Theory of Probabilities; 3, Saturn and its System, by Mr. Proctor, which apparently exhausted the subject; and, 4, A Course of Astronomy, by Dubois. The second edition of Le Ciel had also been received, showing what interest was taken by our neighbours in astronomical science. With regard to the two latter works, however, it was pointed out that as in Le Ciel the labours of Adams, connected with the discovery of Neptune, were passed over in silence; so in the work by Dubois, Mr. De la Rue's observations of the last great eclipse of the sun were entirely ignored, although crowned with the medals of the Royal and the Royal Astronomical Societies. G. G. G. F. Piggott, Esq.,

was balloted for, and duly elected a Fellow of the Society.

Papers by Mr. Hooke and Mr. Tebbutt on Comets, and by Mr. Merrifield on the Artificial Horizon, designed by Col. Strange and Mr. Cooke, were read; also notes on the Lunar Eclipse of April 11, by Mr. A. D. Freeman.

The Rev. W. R. Dawes presented to the Society sixteen drawings of the planet Mars, with remarks upon the same.

The President observed that Mr. Dawes had made so many drawings that a globe of Mars might be constructed from them, and considered that there were enough to enable us to get rid of many discrepancies at present existing with regard to the markings on the planet. He had understood that Mr. Dawes, Professor Phillips, and Mr. Lockyer were to have co-operated in producing a complete series of drawings of Mars; but he thought we might

*We hope to present our readers with an abstract of this important paper in our next number, with illustrations, which Mr. Dawes has kindly prepared for us.

leave each observer to make his independent observations, while the whole series could be combined by others so as to produce a complete work on the subject.

Description of an Aperture-diminishing Eye-Piece, and of a Photometer of Neutral-tint Glass, by the Rev. R. W. Dawes.—The inconvenience attending the application of a variety of apertures to the object-glass of a large telescope, for the purpose of determining the relative brightness of stars, led the writer to the contrivance of an eye-piece by which the same effect can be produced without disturbing the telescope. It consists of a tube having within it a sliding diaphragm, in which are three small holes of different sizes, each of which is capable of being brought into the centre of the tube by the rotation of the diaphragm. An index connected with the diaphragm marks the distance of the hole in use from the zero point of the scale engraved on the edge of the slit in the tube along which the diaphragm is moved. The zero point for each of the holes is, of course, the place where the index stands when the cone of rays from the whole aperture of the object-glass exactly fills the hole. Then, as the diaphragm is moved towards the object-glass, the cone of rays is reduced in proportion to the divisions of the scale passed over.

The correctness of the apertures, calculated on this principle, was established by applying apertures to the object-glass. This contrivance has been in use about five years, and has been found to answer its purpose well.

per

Another photometric arrangement, which was brought into use about the same time, consists in adding to the solar eye-piece invented by the writer one or more sliding wedges of neutral-tint glass, the obscuration extending from the least possible to a pleasant shade for observing the sun. By means of the small forations in the rotating diaphragm plate, one component of a pretty close double star can be excluded from the field, while the brightness of the other is ascertained—an important matter where the difference of brightness is very great. The comparative light of small portions of the moon's surface may also be determined in the same manner. Also, the solar illumination of our atmosphere may be compared with the light of the photosphere itself, and the relative brightness of different parts of the photosphere. The objection urged by the late Mr. Dollond to such uses of the neutral-tint glass of that time (grounded on its imperfect uniformity

of texture and colour), when suggested to him by the writer some twenty-five years ago, seems now to be quite overcome by the improved manufacture of such glass.

The value of the scales, which are engraved on the sliding wedges attached to the solar eye-piece exhibited, was ascertained by comparison with the effect on the same stars of diminishing apertures applied to the object-glass.

Observations of d Cygni, by Mr. G. Knott, of Cuckfield.—The colour of the small star appeared to be No. 3 of Adm. Smyth's scale.

The President said his impression was that the small blue star of d Cygni was variable, and asked Mr. Knott if this was not the

case.

Mr. Knott said it was so, and mentioned that Baron Dumbowski confirmed this. Mr. Knott had seen the star very beautifully the evening before, with a power of 110, on his 74-in. object-glass.

The President said he would take the present opportunity of asking Mr. Dawes what difference he found between the objectglasses of Munich, Alvan Clarke, and Cooke: first, in regard to the definition and colour of planets; secondly, as to the smallness of the spurious disc of any given star.

Mr. Dawes replied that many object-glasses of Alvan Clarke had passed through his hands—in fact, he had, as it were, stood godfather to many of them—and he might say that he usually found the definition of these object-glasses to be almost, if not quite, perfect; but in colour they were not so uniformly correct as Cooke's, which he found extremely fine, both in definition and colour. In reply to a further question put by Mr. Pritchard, Mr. Dawes said that upon the whole, and with a vast number of opportunities of forming an opinion, he felt no hesitation in stating that he considered the object-glasses produced by Alvan Clarke and by Cooke decidedly superior to those he had examined from Munich. As to the diameters of the discs of stars, he found, by measurement, that these depended entirely upon the aperture of the telescope employed. From a considerable experience with telescopes of almost all makes and of all dimensions, he invariably found this to be the case.

Mr. Pritchard said it was very confortable to hear Mr. Dawes state this result of his numerous experiments, because it was entirely in accord with the result of mathematical investigations