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THE BEAUTY OF THE HEAVENS.

25,000 miles ; a distance equal, in extent, to the entire circumference of theearth. It is not difficult to imagine this voyage ; and, by considering thematter in this way, we can even make a tolerable estimate of its extent. Butto reach the sun from the earth, which, in approximate numbers, is ninety-sixmillions of miles, it would be necessary that we should travel at the same rate,without any intermission, and in a direct line, during more than 1100 years !

The instrument, or machine, called the orrery, is an ingeniously contrivedpiece of mechanism, intended to represent the planetary motions ; but, althoughgenerally of very accurate construction and workmanship, it fails to effect theintended purpose ;' namely, to give distinct ideas of the appearance and motionsof the planets. From what we have just seen of their motions and theirdistances from each other, it is evidently impracticable to represent faithfullyeither one or the other; but, to make a practical orrery, it is necessary to shewboth. As an accurately constructed toy, the orrery has merit; but, as a mediumof early instruction in the science, its pretensions seldom justify the costly cha-racter of the machine.

The impracticability of forming a piece of mechanism which shall exhibitany similitude to the relative distances and magnitudes of the planets, must,therefore, be evident; but there have been several arrangements of a mixednature, which perfectly succeed in giving correct first ideas of these movementsand distances, the cost of which is inconsiderable, the scale gigantic, yet per-fectly natural, and the effect more striking than any mechanical contrivancecould produce. We shall describe one of these arrangements, which has fre-quently been put in practice by the author, has been found extremely attractive,and to the perfect satisfaction both of the agents and the spectators, or audience,of the exhibition and lecture, for it partakes of both characters.

The Animated Orrery.

A few of the most active and intelligent boys of a school, previouslyinstructed in the simple elements of the planetary motions, are selected, andplaced on the most extensive level their usual play-ground affords, with a fewwords of admonition and advice on the fidelity and precision expected fromthose who, in their own persons, are to imitate the motions of the planets. Twelveboys are selected, and a card is delivered to each, on which is legibly writtenthe circumstances of one of the eleven planets, or of the sun : such as, in thecase of a planet, its distance from the sun ; its diameter ; the period of its revo-lution in its orbit; the period of its rotation on its own axis ; the inclination ofits orbit to the ecliptic, and the inclination of its axis of rotation to its orbit; itsbulk, or magnitude, compared with the sun ; and whatever other circumstancesmay particularly distinguish it, and which, from the scale of the exhibition, wemay be justified in introducing. A central point of the ground is then fixedon; and from that spot, as a centre, the cardinal points of east, west, north,and south, are represented by a distinguishing mark, or wand, on the borders of