FULTON'S ORRERY.
Titus Orrery conveys a more perfect idea of our solar system than any one that we have seen, whether scenic or solid. It is constructed on a similar principle to the small mechanical orreries sold by opticians, but its movements are far more various and complicated, and its size very much greater—the orbit of Herschel describing a circle of nine feet diameter. The true inclination of the axis of each planet and of the plane of its orbit is shown, and the due relative distances of the planets from the Sun and each other ; and each performs its rotatory or diurnal motion on its axis, and its annual revolution round the sun in the proper relative space of time—the annual revolution of our Earth being mode in a minute, and the others in proportion. The motions of the satellites are equally exact in point of position and time. The eccentricity as well as the inclination of the orbit of Mercury, and the inclinations of the orbits of the secondary planets, Ceres and Pallas, are likewise given. Dials 'milking this hour, the day, the month, and the year, enable the exhibiter to anticipate the course of nature, and to show the precise relative position of every planet and satellite hitherto discovered in our system at any given point of time for a century to come. Thus the visiter, seated comfortably on a tench, may watch the motions of this universe in miniature, and take in at one view the various revolutions of the bodies composing it, as if he were a spirit floating in the realms of space. Allowance must, however, he made for the small size of the Sun and of the three largest planets, as it was found impracticable to make them of proportionate dimensions to our Earth and the rest, so as to show the lesser planets and the satellites. The Sun, for instance, would, if represented to the scale of the Earth, have been nineteen feet in diameter. Jupiter, Saturn, and Herschel, are therefore seven times smaller than their proper dimensions. The mechanism of this Orrery, though apparently complex, combin- ing upwards of two hundred movements, effected by means of one hundred and seventy-five wheels and pinions, is of the most simple construction. As an ingenious and beautiful contrivance, it is alone worthy of admiration ; but representing as it does so completely our solar system, it is a most interesting object to all who desire clearly to comprehend the vastness and order of that portion of the universe of which our globe forms a part. The Orrery being opaque, is exhibited during the day, at :28, Old Bond Street.
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