the ground; you will, however, perceive that there is a stiff wire attached to a weight which is connected with the body of the horse, and by means of such an addition, the horse prances with perfect security at the edge of the precipice; so that the figure which was incapable of supporting itself is actually prevented from falling, by adding a weight to its unsupported end!"

The children admitted the truth of this statement, and were not immediately prepared to explain it.

"The weight, indeed, appears to be added on that side; but, in reality, it is on the opposite side," said the vicar.

"In order to produce the desired effect," observed Mr. Seymour, "the wire must be bent, so as to throw the weight far back, under the table; by which contrivance, since the centre of gravity of the whole compound figure is thrown into the leaden weight, the hind legs of the horse thus become the point of suspension, on which the ball may be made to vibrate with perfect security."

Now I understand it," cried Tom; "instead of the weight supporting the horse, the horse supports the weight."

"Exactly so. You perceive, therefore, from these few examples, that the balancer, by availing himself of such deceptions, and combining with them a considerable degree of manual dexterity, may perform feats, which, at first sight, will appear in direct opposition to the laws of gravity. There is also another expedient of which the balancer avails himself, to increase the wonder of his performances, and that is the influence of rotatory motion, which, you will presently see, may be made to counteract the force of gravity."

"I remember that the most surprising of all the tricks I witnessed was one, in which a sword was suspended on a key, which turned round on the end of a tobacco-pipe; on the top of the sword a pewter-plate was, at the same time, made to revolve with great velocity."

"I well remember the trick to which you allude. The rotatory motion prevented the sword from falling, just as you will hereafter find the spinning of the top will preserve it in an erect position. There is also another effect pro

duced by rotatory motion, with which it is essential that you should become acquainted. You no doubt remember that momentum, or the velocity of a body, will compensate for its want of matter. A number of bodies, therefore, although incapable of balancing each other when in a state. of rest, may be made to do so, by imparting to them dif ferent degrees of motion. I believe that you are now acquainted with all the principles upon which the art of balancing depends; and I have little doubt, should we again witness a performance of this kind, that you will be able to explain the tricks which formerly appeared to you

miraculous."

SO

THE CHINESE TUMBLERS, ILLUSTRATING THE JOINT EFFECTS OF CHANGE IN THE CENTRE OF GRAVITY OF A BODY, AND OF MOMENTUM.-MR. TWADDLETON'S ARRIVAL AFTER A SERIES OF ADVENTURES.-THE DANCING BALLS.-THE PEA-SHOOTER.-A FIGURE THAT DANCES ON A FOUNTAIN. THE FLYING WITCH.-ELASTICITY. SPRINGS. THE GAME OF "RICOCHET," OR DUCK AND DRAKE.-THE REBOUNDING BALL.AMIMALS THAT LEAP BY MEANS OF AN ELASTIC APPARATUS.-THE INDUSTRIOUS FLEAS. A NEW SPECIES OF PUFFING, BY WHICH THE VICAR IS MADE TO CHANGE COUNTENANCE.

EARLY on Monday morning did the young group assemble in the library: they had been told by Mrs. Seymour that their father had received a new toy of a very interesting and instructive nature, and we can easily imagine the eagerness with which they anticipated the sight of it.

"I trust," said Mr. Seymour, "that after our late discussion, the subject of the centre of gravity is thoroughly understood by you all. I have also reason to think that the nature and effects of what is termed momentum have been rendered intelligible to you."

"I certainly understand both those subjects," answered. Tom: and so thought the rest of the party.

"Well, then, I will put your knowledge to the test," observed Mr. Seymour, "for you shall explain to me the mechanism of these Chinese Tumblers." Upon which he produced an oblong box, which, by opening, formed a series of stairs or steps, and took from a drawer at its end two grotesque figures (Clown and Pantaloon), which were connected with each other by two poles, which they appeared. in the attitude of carrying, pretty much in the way that the porters carry the poles of a sedan-chair. The foremost figure was then placed upon the top step, when, to the great astonishment of the whole party, the figures very deliberately descended the several stairs, each turning over the other in succession.

"There was a period in our history," observed Mrs. Seymour, "when so marvellous an exhibition would have subjected the inventor to the penalties of sorcery."

"That," remarked Mr. Seymour, "may be said of most of the other inventions which I have yet in store to illustrate the powers conferred upon us by a knowledge of natural philosophy; but, as far as mechanical skill is concerned, I doubt whether the ancients did not even surpass us, especially in the art of constructing automata; and as quicksilver was known in the remotest ages, I think it not improbable that it was one of the agents employed by them on such occasions. If I remember right, Aristotle describes a wooden Venus, which moved by means of 'liquid silver;' then, again, the moving tripods which Apollonius saw in the Indian temples-the walking statues at Antium, and in the temple of Hierapolis, and the wooden pigeon of Archytas,* ought, undoubtedly, to be regarded as evidences of their mechanical resources. But let us reserve these literary questions for the better judgment or our worthy friend the vicar, and proceed to consider the mechanism of the toy before us. Tom," continued he, "take the figures in your hand and examine them."

Upon this subject, Sir David Brewster's Introductory Letter on Natural Magic will be read with interest and advantage. It has also been very ably investigated by M. C. Magnin, in successive numbers of Revue des Deux Mondes.'

No sooner had the young philosopher received the figures. from the hand of his father than he declared that the tubes were hollow, and that he felt some liquid running backwards and forwards in them.

"You are quite right, my boy," said Mr. Seymour," they contain quicksilver."

"Now then I understand it," cried Tom; "the quicksilver runs down the tubes and alters the centre of gravity of the figures, and so makes them tumble over each other." Well, I acknowledge that is no bad guess as a beginning, and will certainly explain the first movement; but you will be pleased to recollect that the instant a new centre of gravity is thus produced the figures must remain at rest,how, then, will you explain their continued motion ?"

"You said something, I think, about momentum; did you not ?"

"Certainly; and to its agency the continuance of the motions is to be ascribed; but I will explain the operation more fully."

Mr. Seymour then proceeded to point out the mechanism and movements of the toy in a manner which we shall endeavour to convey to our readers by the aid of the annexed engraving.

"As soon as the figure A is placed upon the step D, in the position A B, the quicksilver, by running down the inclined tubes, swings the figure B round to C; and the centre of gravity having been thus adjusted, the whole would remain at rest but for the contrivance to be next described. Besides their connexion with the poles by means of pivots, the figures are connected with each other by silken strings, which keep the figure B steadily in its position, while it traverses the arc until it arrives at C, when their increased tension has the effect of capsizing it, and of thus producing a momentum, which, by carrying its centre of gravity beyond the line of direction, causes it to descend upon the step E, when the quicksilver, by again flowing to the lowest part of the tubes, places the figures in the same position, only one step lower, as they were at the commencement of their action; and thus, by successive repeti