which lengthens or contracts itself, according to the length of the semi-diameter of the ellipsis over which it moves.

A very curious clock, the work of Martinot, a celebrated clock-maker of the seventeenth century, was to be seen in the royal apartments at Versailles. Before it struck the hour, two cocks on the corners of a small edifice crowed alternately, clapping their wings; soon after two lateral doors of the edifice opened, at which appeared two figures bearing cymbals, beat upon by a kind of guards with clubs. When these figures had retired, the centre door was thrown open, and a pedestal, supporting an equestrian statue of Louis XIV, issued from it, while a group of clouds separating gave a passage to a figure of Fame, which came and hovered over the statue. An air was then performed by bells; after which the two figures re-entered; the two guards raised up their clubs, which they had lowered as if out of respect for the presence of the king, and the hour was then struck. Though all these things are easy for ingenious clock-makers of the present day, when we come to treat of Astronomy, we shall give an account of some machines of this kind, purely astronomical, which do honour to the inventive genius of those by whom they were constructed.

IV. Automaton machines of Father Truchet, M. Camus, and M. de Vaucanson.

TOWARDS the end of the seventeenth century, Father Truchet, of the royal Academy of Sciences, constructed, for the amusement of Louis XIV, moving pictures, which were considered as very

remarkable master pieces of mechanics. One of these pictures, which that monarch called his little opera, represented an opera of five acts, and changed the decorations at the commencement of each. The actors performed their parts in pantomime. The representation could be stopped at pleasure; this effect was produced by letting go a catch, and by means of another the scene could be made to re-commence at the place where it had been interrupted. This moving picture was sixteen inches and a half in breadth, thirteen inches four lines in height, and one inch three lines in thickness, for the play of the machinery. An account of this piece of mechanism may be found in the eulogy on Father Truchet, published in the Memoirs of the Academy of Sciences, for the year 1729.

Another very ingenious machine, and in our opinion much more difficult to be conceived, is that described by M. Camus, a gentleman of Lorrain, who says he constructed it for the amusement of Louis XIV, when a child. It consisted of a small coach drawn by two horses, in which was the figure of a lady, with a footman and page behind.

If we can give credit to what is stated in the work of M. Camus, this coach being placed at the extremity of a table of a determinate size, the coachman smacked his whip, and the horses immediately set out, moving their legs in the same manner as real horses do. When the carriage reached the edge of the table, it turned at a right angle, and proceeded along that edge. When it arrived opposite to the place where the king was seated, it stopped, and the page getting down opened the door, upon which the lady alighted, having in her hand a petition which she presented with a curtsey.

After waiting some time, she again curtsied, and re-entered the carriage; the page then resumed his place, the coachman whipped his horses, which began to move, and the footman, running after the carriage, jumped up behind it.

It is much to be regretted that. M. Camus, instead of confining himself to a general account of the mechanism, which he employed to produce these effects, did not enter into a more minute description; for, if they are true, it must have required a very singular artifice to produce them, and the same means might be applied to machines of greater utility.

About thirty or thirty-five years ago, three very curious machines were exhibited by M. de Vaucanson, viz, an automaton flute-player, a player on the flageolet and tambourine, and an artificial duck. The first played several airs on the flute, with a precision greater perhaps than was ever attained to by the best living player, and even executed the tonguing, which serves to distinguish the notes. According to M. de Vaucanson, this part of the machinery cost him the greatest trouble. In a word, the tones were really produced in the flute by the proper motion of the fingers.

The player on the flageolet and tambourine performed also some airs on the first of these instruments, and at the same time kept continually beating on the latter.

But the motion of the artificial duck, in our opinion, was still more astonishing; for it extended its neck, raised up its wings, and dressed its feathers with its bill; it picked up barley from a trough, and swallowed it; drank from another, and, after various other movements, voided some

matter resembling excrements. The first time I saw these machines I immediately discovered some of the artifices employed in regard to the two former, but I confess that the latter baffled my pene

tration.

We have also of late been amused, by M. Droz and M. Maillardet, &c, with the surprising performances of the chess-players, the small but sweet singing-bird, the writing figure, the musical lady, the conjurer, the tumbler, &c, &c.

§ V. Of the Machine at Marly.

It will doubtless be allowed, that the machines above mentioned are, in general, more curious than useful; but there are other two, the celebrity and utility of which require that we should here give them a place. These are the machine of Marly, and that known under the name of the steam engine. We shall begin with the former, of the construction and effects of which the following brief description will give some idea.

The machine of Marly consists of 14 wheels, each about 36 feet in diameter, moved by a stream of water, confined by an estacade, and received into so many separate channels. Each wheel has at the extremities of its axis, two cranks, and this forms 28 powers, distributed in the following manner.

It must however be first observed, that the water is raised, to the place to which it is to be conveyed, by three different stages; first from the river to a reservoir, at the elevation of 160 English feet above the level of the Seine; then to a second reservoir 346 feet higher; and from the latter to the

summit of a tower, somewhat more than 533 feet

above the river.

Of the 28 cranks, above mentioned, eight are employed to give motion to 64 pumps; which is done by means of working beams, having four pistons at each extremity of their arms: this makes eight to each working beam, which are drawn up and pushed down alternately. These 64 pumps force up the water to the first reservoir; and this reservoir furnishes water to the first well, on which is established the second set of pumps.

Eleven more cranks are employed to force the water from the first well to the second reservoir. This is done by means of long arms adapted to these cranks, which move large frames, to one of the arms of which are attached strong iron chains, that extend from the bottom of the mountain to the first well. These chains, called chevalets, are formed of parallel bars of iron, the extremities of which are bound together by iron bolts, and are supported at certain intervals by transversal pieces of wood, moveable on an axis, that passes through the middle of each; so that when the upper bar of iron, for example, is drawn down by the lower end, all these pieces of wood incline in one direction, and the lower bar moves backwards and pushes in a direction contrary to the upper one. These bars or

chains serve to put in motion the working beams, or squares, and the latter move the pistons of 80 sucking and forcing pumps, which raise the water from the first well to the second reservoir.

In the last place, nine other cranks, by a similar mechanism, put in motion those chains, called the grands chevalets, which move the pumps of the