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The board which serves as a stand, represents a plane parallel to the ecliptic. The cylindrical block a has its upper surface cut obliquely, so that its plane may form an angle of 5° 9 with the ecliptic; that being the inclination of the moon's orbit to it. This oblique surface is covered with paper, and a graduated circle described on it, through which a diameter must be drawn, correctly parallel to the intersection of the two planes, to represent the line of the moon's nodes; the ends of this diameter must be the 0°, and 180° of the division on the circle. The block a turns round in, and concentric with, the ring B, on the surface of which a graduated circle is also drawn on paper: this lower piece B is made with a pivot to fit into a hole in the board, to admit of A and B being turned round together on their centres. The pillar c is screwed fast into A; it has an oblique shoulder to carry the wire axis of the earth at the proper inclination of 66° to the ecliptic; this shoulder turns on c to allow of the earth’s axis being set to point to the proper sign of the Zodiac in the circle on B.

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A is a light frame to carry the moon, m; the opening is contracted to the thickness of c at one end, by two ivory (or brass or wood) slips fixed on its under-side and flush with that face; when y, therefore, is turned round, resting on the oblique face of A, these slips prevent any lateral motion. At the other end of h a square plate of ivory (wood or brass) is screwed on the under-side also, the upper face of this plate, therefore, coincides with the plane of the surface of A: on this plate a graduated circle is described concentric with the moon's axis. The moon is carried on a double pedestal, the lower piece having a pivot to turn in the central hole of the plate, the under-face of the pedestal is cut bevelled to form an angle of 5° 9' with its axis, so that by turning the pedestal round, the axis of the moon may be made to stand perpendicular to the ecliptic in every position of n, instead of being perpendicular to that frame, as it would be without this contrivance.

The length of the frame, n, being decided on at pleasure, (the one before us is ten inches, but the larger the better,) divide the length of the opening, from the centre of the circle on the plate, into thirty-two parts, (thirty being the moon's mean distance in earth's diameters.) Then, making the centre of the circle zero, mark the 30th division on the ivory slips, and subdivide a division or two on each side into tenths, to serve as a scale for setting the moon at her true distance from the earth. The ball E, to represent the earth, must be made accurately equal to one division in diameter, or one thirtieth of the mean distance, and it must have an equatorial line drawn on it: the moon, m, is to be made •36 of the earth's diameter, and may be measured from the scale on the slips. In the instrument we are describing, the moon is made in one piece with the upper part of its stand, which turns round on the lower pedestal, before mentioned, to allow of the unblackened half of the surface being turned in the direction of the sun, as indicated by the line BK, without altering the adjustment of the pedestal. But if a larger scale be adopted, the moon may be made to slide on a fine needle stuck perpendicularly into the pedestal; in either case there must be contrived means by which the moon may be set correctly at the same height above the surface of the plate, when the moon is in her node, that the earth is raised above the centre of the surface of a; or in short, that the line joining the centres of the two balls may, in that position, be parallel to the board, and consequently represent one in the true ecliptic.

The dial, D, is intended to supply the place of meridians on the earth, and should be drawn on paper with care, for the latitude of the place, and being then mounted on a conical piece of wood, cut to have its flat surface truly to represent the horizon of that place: a hemispherical hole must be cut out, so that when the earth is sunk in it the radiating lines of the dial may tend to its centre*.

The pillar, K, is to indicate the direction in which the sun is, a piece of card with a hole to represent the apparent diameter of the sun is stuck upright on its top, the centre of this hole must be made exactly as high above the board as the centre of the earth. The diameter of the hole is of course to be made the chord of the angle, subtended by the sun from the earth, the arc being described with the radius equal to the distance of K from E.

There must be a counterpoise put on the end of the frame, H, to keep its under-side close down on the top of A, and to steady it while it is moved.

To adjust the Lunarium. Turn B round on its axis till the line AK of the sun's direction is opposite the degree on the graduated circle, corresponding to the sun's longitude for the time. Then turn a round in B, to bring the moon's ascending node into its proper degree on the same circle. Turn the earth’s axis round on c till it lies in the plane of the solstices, perpendicular to the ecliptic. Raise or lower the dial and earth till the centre is perpendicularly over that of the pillar c, or over the centre of the ring B: set the dial in the meridian, as indicated by the earth’s axis. Turn a round till the line of the nodes on a coincides with

* This dial is, of course, not essential, | tion, even in the latter case : the nicety and may be dispensed with if the earth be required to construct it properly is a good large enough to admit of meridians being exercise, and it materially adds to the drawn on it, but we would advise its adop- | merits of the Lunarium.

that joining the axis of the earth and moon ; when in this position, raise or depress the moon on its pedestal till its centre is at the same height as the earth's above the surface of the board ; that is, the moon must be put really in the ecliptic when she is in her node ; and the corresponding adjustment for the sun's centre may be made at the same time. Then move the frame, H, till its axis, or the line parallel to the radius vector of the moon, point to the degree of longitude on a, in which the moon is at the time of adjustment; in this new position, turn the lower pedestal of the moon round on its axis, till that axis is perpendicular to the ecliptic; a small index stuck in the pedestal to point to the right degree on the divided circle, will allow of this adjustment being made with facility and accuracy at once *. Lastly, move the frame, n, backwards or forwards till the moon be brought to her true distance from the earth at the time of adjustment, by means of the scale on the slips ; and set the enlightened half of the moon towards the sun, that is, make the plane of the line separating the light dark halves perpendicular to the sun's direction. The board

may

be made to slide between fillets of wood nailed down on one much larger. These fillets being struck out, arcs of concentric circles of such radii, that the path of the earth, when moving between them, may be the circle described by the earth at its true proportionate mean distance, deduced from that originally assumed for the earth and moon: these fillets may be spaced out into days: this addition to the Lunarium will enable it to show that the curve described in space by the moon, is not a nodated cycloid, as common orreries show it, but one slightly undulatory, and always concave to the sun.

The young learner must be impressed with the characteristic of this instrument, in which, indeed, its great merit consists; it is only true for one fixed position, and will not admit of the moon's being made to revolve round her whole orbit, for before she has moved through one twentieth part, her mean distance and the place of her node has altered, but by the simple and easy adjustments which a common ephemeris will enable him to make in as short time as is requisite to read these instructions, he has the earth and moon in their real positions, and by moving the moon for a short arc in her orbit, he sees the direction of her motion and its results. But if he look through the hole on k, he must bear in mind that he is no longer an observer from the earth, he must transport himself in imagination to the sun, or at least to the point in the earth's radius vector, represented by the aperture on K.

He will see an eclipse of the earth when to an inhabitant of it the sun is eclipsed, and he will observe an eclipse of the moon by the body of the earth, instead of its being obscured only by passing through the shadow of our planet. By

a

* The degrees on that circle must be 180°, no description can make these nicenumbered accordingly, but the means of ties intelligible to the dull, and they are ascertaining where they are to commence not needed by the acute : all that can will be best understood by looking at the be said is, that the moon's axis must be instrument; it should be contrived that perpendicular to the ecliptic, and not to the small index should point when the the plane of h, otherwise there will be adjustment is made to the degree of the a discrepancy between the moon's real circle on A, seen in the axis of h: when, position and that which it ought to have, therefore, the moon is in her nodes, the as given by the horizontal circle on B. index on the pedestal must point to 0° or

turning the dial and earth round on the axis, and keeping his eye in the plane of the former, he may observe the moon's rising and setting, and the hour at which it happens, and, in short, with care and skill he may acquire correct notions of the cause of all the lunar phenomena.

In conclusion we would observe, in answer to those who might consider the subject and our mode of treating it too elementary for our Magazine, that although it may not interest them personally, yet as no child could make or adjust such an instrument without assistance, and as every one is directly or indirectly interested in the instruction of young people, the paper and the toy it describes are not so inconsiderable as they might at first appear.

THE PROGRESS AND STATE OF SCIENCE IN BELGIUM. In our opening number we announced our intention of specially devoting a portion of our Journal to the communication of whatever might appear most generally interesting in Foreign Science, and especially from time to time to give such abstracts as we might be able to obtain of its general condition in the several countries of Europe.

This pledge we have partially redeemed by the various notices we have inserted, referring to foreign discoveries and researches. We hope to fulfil the same promise to a greater extent in the present article. We have been kindly favoured with a copy of the Bulletin of the Royal Academy of Sciences at Brussels, containing the detailed proceedings of the public Séance of Dec. 16th, 1835; and shall present our readers with what has appeared to us the truly interesting Report, delivered on that occasion by the perpetual secretary, M. Quetelet.

In doing this, we have thought it best to adhere closely to the author's own words, and, instead of attempting any compilation of our own, to present his luminous and often eloquent views in a translation, if not always strictly literal, yet always following the tenour of his reflections. We think it right to apprize our readers of this, in order to account for an occasional style of expression which would not perhaps be adopted by an original English writer. This, however, we do not doubt, will rather be regarded by our readers as characteristic, and as only tending to bring more vividly to their minds the actual tone of scientific views at present prevailing in Belgium. Without further preface then we commence. Report of the Permanent Secretary on the Labours of the ANCIENT

IMPERIAL AND ROYAL ACADEMY OF BRUSSELS. In some introductory remarks, the distinguished author gives a rapid sketch of the progress of arts and sciences in Belgium in former centuries :-their flourishing condition under Charles V., and subsequent decline, and almost total extinction. The dawn of a better state of things, however, approached :

It was under the auspices of Maria Theresa, of glorious memory, that the Imperial and Royal Academy of Brussels was formed. The few

really well-instructed men that Belgium contained, united themselves with several foreigners of distinction, and the language of science was once more heard amongst us.

“ The labours of this learned body were crowned with a brilliant success, and obtained great favour with the nation, who well understood that the opinion that would be formed of her by foreigners, would henceforth depend on the esteem in which an assemblage of men would be held, who might be considered as her representatives of national intelligence. Unhappily, this success was of short duration.

“A revolution, which broke down the greater part of the props of the ancient social edifice, and renewed the political constitution of many states, also changed our destinies.

"The Academy of Brussels was suppressed; its members were dispersed ; and when, at a later period, we became a part of the great body of the French empire, of which the whole intellectual life appeared concentrated at Paris, it might be asked with reason, whether Belgium had not again fallen into its ancient state of torpor.

“ The Imperial and Royal Academy of Brussels, whose important services are to this day too little appreciated amongst us, appeared then but for an instant, and as a nrelude to a new era which was soon to open before us, and to restore to us, with our ancient liberties, our former taste for the arts, literature, and science. When in 1816 this learned body was re-organized, the few members who were yet living, were called upon to compose it; but some bad expatriated themselves, and others were for the most part too aged to be able a second time to co-operate in the intellectual regeneration of their country. At the present time these men of another age have successively become extinct.

“The new academy, in creating an annual public session, was desirous of consecrating the memory of the 16th of December, the day on which the ancient Academy of Brussels was founded, and which, by a happy coincidence, is also the birth-day of our august monarch; and they have deemed that they could not with more propriety usher in their public session, than by giving a rapid sketch of the labours of its predecessors, as constituting the finest eulogium that could be offered to their memory.

“ It is to me that has been intrusted the honour of paying this tribute of gratitude,—this sacred debt, which is indeed also that of the nation.

“I will not here stop to retrace the origin or the first labours of the Academy, the recital of these may be found detailed in the volumes which commence the former, and the new series of our memoirs.

“ I shall only speak of its foundation, with a view to make that character of grandeur and magnificence which was imprinted on it, and which would do honour to the most enlightened governments, duly appreciated. Its august foundress had well perceived, that in order to restore the sciences in a country where they had nearly fallen into complete oblivion, it was necessary to encircle with honours, and worthily to recompense those who cultivated them with success. She constituted the Prince of Stahremberg her minister plenipotentiary to represent her in the Academy, in the capacity of protector; and the chancellor of Brabant was invested with the presidency. The royal library was assigned as the ordinary place of assemblage. The Academy had moreover the enjoyment of that rich collection, which had formerly belonged to the duke of Burgundy: permission was granted it to use as its great seal the arms of that illustious house, and thus of associating its name with those of the brightest recollections of our national history. Funds were liberally accorded for the printing of the memoirs, for remunerating contributors, and

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