“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,[[11]] ought, undoubtedly, to be regarded as evidences of their mechanical resources. But let us reserve these literary questions for the better judgment of 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.”
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, papa?”
“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 repetitions of the same changes, it is quite evident that the figures must continue to descend as long as any steps remain for their reception.”