employment of a system of mechanical notation invented by Mr. Babbage, which places distinctly in view at every instant the progress of motion through all the parts of this or any other ma chine; and by writing down in tables the times required for all the movements, this method renders it easy to avoid all risk of two opposite actions arriving at the same instant at any part of the engine.

In the printing part of the machine less progress has been made in the actual execution than in the calculating part. The cause of this is the greater difficulty of its contrivance, not for transferring the computations from the calculating part to the copper or other plate destined to receive it, but for giving to the plate itself that number and variety of movements which the forms adopted in printed tables may call for in practice.

The practical object of the calculating engine is to compute and print a great variety and extent of astronomical and navigation tables, which could not be done without enormous intellectual and manual labor, and which, even if executed by such labor, could not be calculated with the requisite accuracy. Mathematicians, astronomers, and navigators do not require to be informed of the real value of such tables; but it may be proper to state, for the information of others, that seventeen large folio volumes of logarithmic tables alone were calculated at an enormous expense by the French government; and that the British government regarded these tables to be of such national value, that they proposed to the French Board of Longitude to print an abridgment of them at the joint expense of the two nations, and offered to advance £5000 for that purpose. Besides logarithmic tables, Mr. Babbage's machine will calculate tables of the powers and products of numbers, and all astronomical tables for determining the positions of the sun, moon, and planets; and the same mechanical principles have enabled him to integrate innumerable equations of finite differences, that is, when the equation of differences is given, he can, by setting an engine, produce at the end of a given time any distant term which may be required, or any succession of terms commencing at a distant point.

Besides the cheapness and celerity with which this machine will perform its work, the absolute accuracy of the printed results deserves especial notice. By peculiar contrivances, any small error produced by accidental dust or by any slight inaccuracy in one of the wheels, is corrected as soon as it is transmitted to the next, and this is done in such a manner as effectually to prevent any accumulation of small errors from producing an erroneous figure in the result.

Description of the Automaton Chess-player.

The Chess Automaton was the sole invention of Wolffgang de Kempelen, a Hungarian gentleman, Aulic counsellor to the royal chamber of the domains of the emperor in Hungary, and celebrated for great genius in every department of mechanics. From a boy, he had trod in the path of science, and was incontestably of first-rate capabilities as a mechanician and engineer. Invention was his hobby, and he rode it furiously, even to the partial impov. erishment of his means. M. de Kempelen, being at Vienna in the year 1796, was invited by the empress Maria Theresa to be present at the representation of certain magnetic games, or experiments, about to be shown in public at the imperial court by M. Pelletier, a Frenchman. During the exhibition, De Kempelen, being honored by a long conversation with his sovereign, was induced casually to mention that he thought he could construct a machine, the powers of which should be far more surprising, and the deception more complete, than all the wonders of magnetism just displayed by Pelletier. At this declaration, the curiosity of the empress was naturally excited; and, with true female eagerness for novelty, she drew from De Kempelen a promise to gratify her wishes, by preparing an early and practical proof of his bold assertion. The artist returned to his modest dwelling at Presburg, and girded up his loins to the task. He kept his word with his imperial mistress; and in the following year presented himself once more at the court of Vienna, accompanied by the Automaton Chess-player. Need we say that its success was triumphantly complete?

The Chess-player was a figure as large as life, clothed in a Turkish dress, sitting behind a large square chest or box, three feet and a half long, two feet deep, and two and a half high. The machine ran on castors, and was either seen on the floor when the doors of the apartment were thrown open, or was wheeled into the room previous to the commencement of the exhibition. The Turkish Chess-player sat on a chair fixed to the square chest; his right arm rested on the table, and in the left he held a pipe, which was removed during the game, as it was with that he made the moves. A chess-board eighteen inches square, and bearing the usual number of pieces, was placed before the figure. The exhibiter then announced to the spectators his intention of showing the mechan ism and after having unlocked the doors and shown every part of the machine, to prove that it was impossible for any one to be concealed within, the Automaton was ready for play. An opponent having been found among the company, the figure took the

first move. At every move made by the Automaton, the wheels of the machine were heard in action; the figure moved its head, and seemed to look over every part of the chess-board. When it gave its check to its opponent, it shook its head thrice, and only twice when it checked the queen. It likewise shook its head when a false move was made, replaced the adversary's piece on the square from which it was taken, and took the next move itself. In general, though not always, it won the game.

During the progress of the game the exhibiter often stood near the machine, and wound it up like a clock after it had made ten or twelve moves. At other times he went to a corner of the room, as if it were to consult a small square box, which stood open for

this purpose.

The chess-playing machine, as thus described, was exhibited after its completion in Presburg, Vienna, and Paris, to thousands, and in 1783 and 1784 it was exhibited in London and different parts of England, without the secret of its movements having been discovered. Its ingenious inventor, who was a gentleman and a man of education, never pretended that the Automaton itself really played the game. On the contrary, he distinctly stated "that the machine was a bagatelle, which was not without merit in point of mechanism, but that the effects of it appeared so marvellous only from the boldness of the conception, and the fortunate choice of the methods adopted for promoting the illusion."

Upon considering the operations of this Automaton, it must have been obvious that the game of chess was performed either by a person enclosed in the chest or by the exhibiter himself. The first of these hypotheses was ingeniously excluded by the display of the interior of the machine; for as every part contained more or less machinery, the spectator invariably concluded that the smallest dwarf could not be accommodated within, and this idea was strengthened by the circumstance that no person of this descrip. tion could be discovered in the suite of the exhibiter. Hence the conclusion was drawn that the exhibiter actuated the machine either by mechanical means conveyed through its feet, or by a magnet concealed in the body of the exhibiter. That mechanical com. munication was not formed between the exhibiter and the figure was obvious from the fact that no such communication was visible, and that it was not necessary to place the machine on any partic. ular part of the floor. Hence the opinion became very prevalent that the agent was a magnet; but even this supposition was exclu ded, for the exhibiter allowed a strong and well-armed loadstone to be placed upon the machine during the progress of the game: had the moving power been a magnet, the whole action of the ma

chine would have been deranged by the approximation of a loadstone concealed in the pockets of any of the spectators.

The Chess-player continued the wonder of all Europe for a period of over sixty years, without the secret of its movement being divulged, though many were the attempts to unravel the mystery. It was exhibited in all the courts of Europe, and even kings condescended to try a game. Among other monarchs whose curiosity was excited was Eugene Beauharnois, then king of Bavaria, who bought the machine in order to ascertain the secret. Dismissing his courtiers from the room, the king then locked the door, and every precaution was taken to ensure his acquiring a sole knowledge of the hidden enigma. The prince was left alone with the demonstrator: the latter then unhesitatingly and in silence flung open simultaneously all the doors of the chest; and prince Eugene saw-what he saw!

Napoleon, himself a chess-player, honored the Automaton by playing a game in person against it. The contest was marked by an interesting circumstance. Half a dozen moves had barely been made, when Bonaparte, purposely, to test the powers of the machine, committed a false move; the Automaton bowed, replaced the offending piece, and motioned to Napoleon that he should move correctly. Highly amused, after a few minutes the French chief again played an illegal move. This time the Automaton without hesitation snatched off the piece which had moved falsely, confiscated it, and made his own move. Bonaparte laughed, and for the third time, as if to put the patience of his antagonist to a severe trial, played a false move. The Automaton raised his arm, swept the whole of the pieces from the board, and declined continuing the game!

While the machine was exhibiting in England, in 1785, a Mr. Philip Thicknesse printed a pamphlet in which he denounced the Automaton as a piece of imposture in no measured terms. He assumed that a child was confined in the chest, from ten to fourteen years of age, who played the game; but added, absurdly enough, that Master Johnny saw the state of the board reflected from a looking-glass in the ceiling. He had previously discovered a case of curious imposture worth quoting:

Forty years since," writes Thicknesse, "I found three hundred people assembled to see, at a shilling each, a coach go with. out horses. Mr. Quin, the Duke of Athol, and many persons present, were angry with me for saying that it was trod round by a man within the hinder wheel; but a small paper of snuff put into the wheel, soon convinced all around that it could not only move, but sneeze, too, like a Christian!" We wonder how De Kempelen

would have met a proposition to throw an ounce or two of snuff upon speculation among his springs and levers?

Notwithstanding all the attempts, the secret of the Automaton Chess-player was never solved, until one of the persons implicated in the fraud turned king's evidence. Several persons almost hit the mark; but none fairly planted his arrow in the gold. The man who really played the Chess-Automaton was concealed in the chest. Such, in half a dozen words, is the sum and substance of the whole truth of the contrivance; but the manner in which his concealment was managed is as curious as it is ingenious.

He sat on a low species of stool, moving on castors, or wheels, and had every facility afforded him of changing and shifting his position, like an eel. While one part of the machine was shown to the public, he took refuge in another; now lying down, now kneeling; placing his body in all sorts of positions, studied beforehand, and all assumed in regular rotation, like the A B C of a catechism. The interior pieces of clock-work-the wheels and make-weight apparatus, were all equally moveable; and additional assistance was thus yielded to the fraud. Even the trunk of the Automaton was used as a hiding-place, in its turn, for part of the player's body. A very short amount of practice, by way of rehearsal, was found sufficient to meet the purposes of the occasion; and one regular order being observed by the two confederates as to the opening the machine, a mistake rarely or never occurred. Should any thing go radically wrong, the prisoner had the means of telegraphing his jailer, and the performance could be sus. pended.

"But," says the reader, "what becomes of the vast apparatus of wheels, springs, levers, and caskets? Why did Maelzel require to wind up his man of wood and brass?" The answer is short. These things were the dust thrown in the eyes of the public. The mind of the gaping spectator dwelt on the sound of the springs and wheels, and was thus diverted from the main question. Every adjunct that intellect could devise was skilfully superadded, to enhance the marvel. The machine was railed off, for a now tolerably clear reason; and a lighted candle having been first introduced into the body of the Automaton, to show the interior, at a moment nothing could be seen, was purposely left burning close at hand, in order to prevent any inopportune rays of light flashing from the interior, where a second candle was necessarily in process of ignition.

The director of the Automaton was quietly seated, then, in the interior. All public inspection over, and the doors being safely closed, he had only to make himself as comfortable as he could