A musical machine, on the principle of the organ, which, by peculiar modification of the pipes, produces an excellent imitation of the tones of all the most admired wind instruments; the combined effect of the whole being similar to that of a numerous and well-chosen orchestra. This magnificent contrivance, unrivalled in this or any other country, is the invention of Messrs. Flight and Robson, who spent five years in its completion; and as a popular description of it has not yet appeared, and cannot fail to be acceptable to the amateurs both of musical and mechanical science, we propose to give such an account of the instrument as may serve to convey a general idea of its construction. In the apollonicon, as in the organ, the sound is produced by a current of air, urged by bellows, through several series of vertical pipes. In the apollonicon there are two pair of bellows, placed below the floor of the apartment in which the instrument stands; the wind from which passes through a reservoir and a tube, called a wind trunk, into an air-tight compartment, called a wind chest.

The pipes which, by various modifications of their construction, produce the sounds of the different instruments, are ranged in rows one behind the other, parallel to the front of the machine, in the order of the gamut, each note and half note having its separate pipe, and each parallel row representing a different instrument; the pipes producing the same note in every instrument lying in a straight line from front to back of the instrument, or parallel to its sides. Thus the pipes producing the note A on the flute, clarionet, bassoon, etc, all lie in a line parallel to the sides of the instrument. From the upper part of the wind chest proceeds a horizontal platform, termed the bottom board, having a series of channels cut in its upper surface, corresponding to each note of the different scales, and extending longitudinally from front to rear of the machine. Above the bottom board, and at right angles to the channels, are a series of grooves, corresponding to the transverse ranges of pipes, or the number of the different instruments in each groove, are three slides, placed one over the other, and through all three are cut narrow passages, opening into each of the wind channels in the bottom board.

Over the slides is placed the top board, into which the pipes are inserted, communicating with the wind channels through the apertures in the slides. The use of these slides is to cut off occasionally the communication of any particular instrument with the wind chest, so as to cause that instrument to cease playing, which is effected as follows: - the space between each aperture in the slides is somewhat greater than the width of the wind channels, so as to cover the channels completely, and thereby cutting off the communication with the instrument to which the slide belongs. Only one slide in each set of slides is in operation at one time; the apertures in the other two sets being over the wind channels, and below the apertures of the instruments. One set of slides being used when the instrument is played by the mechanical action of the machine, another set is moved by pedals, and the third set by hand, when it is played by the keys. At that end of each wind groove that opens into the wind chest, are two hanging valves, called pallets, which admit the air into, or exclude it from, the wind grooves; and the art of performing upon the machine consists in the management of the pallets and stops before described; the air or tune being produced by the pallets, and the stops regulating the instruments, upon which the air is played.

We shall now proceed to describe the means by which this is effected. - The machine may be played in two ways, either by performers seated at ranges of keys, as in other organs, or by mechanical means: and as *his latter method is the distinguishing character of the machine, and has called forth so much ingenuity in its execution, we shall describe it first. The principle is as follows: - to one set of the pallets is attached a series of wires (one to each pallet) passing through holes in a brass plate in the bottom of the wind chest, which are just sufficiently large to allow the wires to move easily, without allowing the air to escape from the wind chest. These wires (60 in number, being one to each note of the scale of the machine,) are connected to one end of a series of small steel levers, set in a frame below the wind chest, the outer end of the levers resting upon the surface of a cylinder somewhat longer than the key-frame; a number of small pins and bent wires or brackets project a short distance beyond the circumference of the cylinder, ranged in lines across the axis, and by the revolution of the cylinder, one or more of these pins or brackets are brought in contact with the outer end of the keys, which are thus raised, whilst the other end of the keys, and the pallets corresponding, are proportionably depressed; the wind passes from the wind chest into the wind passages.

The length of time the pallets continue open is regulated by the length of the brackets; and when, by the revolution of the cylinder, the brackets come clear of the keys, the outer end of the key falls upon the cylinder, the pallet is closed by a spiral spring, and the communication with the wind grooves is cut off. Beyond the keys, and towards the end of the key-frame, is a set of similar keys, moved by brackets on the surface of the cylinder, similar to the former, only projecting somewhat more; these keys (called shifting keys,) by an ingenious arrangement (which we shall afterwards describe at length), give motion to an equal number of levers, each one of which moves in or out one or more of the set of stops which are governed by the cylinder, and thus opens or cuts off the communication of the corresponding instrument or set of pipes. For the sake of simplicity, we describe the brackets as ranged in hues standing right across the axis, which is not quite correct, as, in this case, the same keys would be moved at the corresponding part of each revolution of the cylinder, and consequently only very short pieces could be performed, or the cylinder must be of an inconveniently large diameter.