ORGAN. 



not to be treated in the above manner, 

 and require to be distilled with inflam- 

 mable matters in an earthen retort. See 

 Kirwan's Mineralogy. 



ORGAN. Having 1 , under the article 

 MUSICAL instruments, given a pretty full 

 account of this instrument, we shall here 

 only give a description, with figures, of 

 the barrel-organ. See Plate I. Barrel 

 Organ, and Plate II. parts of ditto. 



The barrel-organ is generally portable, 

 and is so contrived, that the same action 

 of the hand, which turns the barrel, sup- 

 plies the wind, by giving motion to the 

 bellows : it consists of three principal 

 parts : 1. The pipes, by which the sound 

 is produced. 2. The bellows, supplying 

 them with air. 3. The barrel and keys, 

 by which the pipes are sounded at pro- 

 per intervals. The pipes are of two 

 kinds, of metal and of wood : the wood- 

 en oaes are a square trunk of deal wood, 

 A B, (fig, 5) closed at one end by a plug 

 of wood, D, and at the other by a piece 

 of wood, E, containing a crooked pas- 

 sage to bring air to the pipe, through the 

 short tube, F ; a is a piece of oak board, 

 glued to the block E, and hollowed out to 

 communicate with the crooked passage 

 in it, and leaving a small crack, between 

 it and the edge of the block, E, through 

 which the air issues in one continued 

 stream ; in its passage it is divided by 

 the edge of one side of the trunk, A, 

 which is cut as sharp as possible for that 

 purpose, and which is exactly in the same 

 line with the orifice whence the air is 

 emitted. 



The sound is produced by the vibra- 

 tion of the air which is contained in the 

 trunk, A, and by increasing or diminish- 

 ing the length of the pipe, the tone is 

 altered at pleasure, to bring it to the pro- 

 per note it is to perform when placed in 

 the instrument : this is done by sliding 

 the plug, D, up or down in the pipe. 



A metal pipe, a section of which is 

 shown in fig. 6, is nearly the same in its 

 operation, though different in its con- 

 struction. It is a cylindric tube, of a 

 mixture of lead and tin ; A B, (fig. 6) 

 open at one end, and nearly closed at 

 the other by a lump of the same meta], 

 E, which is circular for about two-thirds 

 round, and fits the end of the pipe ; the 

 other third is a straightedge : the upper 

 edge of the conical pipe, F, is bent to 

 be parallel to this, and thus forms a small 

 cleft similar to the wooden one, for the 

 passage of the air, the lower edge of the 

 cylindrical pipe, A B, is bent into the 

 line of the cleft and cut sharp, to divide 

 the current of air; these pipes are open 



at top, and are brought to tune by bend 

 ing the pipe at the top, and thus altering 

 its bulk : a is a piece of metal, called the 

 ear, soldered upon the pipe at each end 

 of the cleft, to prevent the stream of air 

 being dispersed before it meets the sharp 

 edge of the pipe, B A ; in the small pipes 

 this is not applied. 



The bellows of the organ are double, 

 as shewn in fig. 1, Plate I ; that is, they 

 are two distinct pairs, E, F, connected: 

 together at their hinge ; so that when 

 one is opening, and filling with air, the 

 other is forcing its air out into the regu- 

 lator, D ; the bellows receive their mo- 

 tion by a rod, d, from a crank, a, on a 

 spindle which comes through the box, in 

 which the machine is enclosed, And hat 

 a handle on it by which it is turned. The 

 regulator, D, is exactly similar to another 

 pair of bellows, and "is filled with air 

 from the bellows, E F, below it, through 

 two valves in the bottom board over the 

 bellows ; from this regulator the air pro- 

 ceeds through the passage, b ef, (seen 

 better in the section), fig. 2, &c. 



Fig. 2, Plate I, to a long trunk, ,-, go- 

 ing under the pipes called the air-chest, 

 which communicates with them by a small 

 valve, A, under each, it is kept shut by a 

 small wire spring, and is opened by a 

 wire fixed to the end of a rod, G ; above 

 the valve, the passage enlarges, and 

 goes under two small wooden sliders or 

 stops, n m, and from thence in two dis- 

 tinct passages to the wooden and metal 

 pipes, N M. 



The air-chest, g, is common to all the 

 pipes, and each pair (of wooden and me- 

 tal pipes) has a valve, A, and spring to 

 themselves; the small passage above 

 each valve belongs to each pair of pipes, 

 and has no connection with the other; 

 the two stops belong to all the pipes ; m, 

 to the metal, and n, to the wooden ones ; 

 they are long slips of wood drilled with so 

 many holes as there are pipes, and at the 

 same intervals, (the disposition of the 

 pipes is shown in fig. 3, which is a plan of 

 the whole instrument put together) ; so 

 that when the holes are over the pas- 

 sages, the air has free communication 

 from the valve to the pipes ; but when 

 the stops are drawn out, the interval be- 

 tween each hole applies itself to the holes 

 under the pipes, and thus stops the pas- 

 sages. 



We now come to describe the appara- 

 tus which opens the valves, h, at the pro- 

 per time, to perform the note of a piece 

 of music. 



The axle, on which the crank, a, (fig. 

 1, 2, and 3) is formed, has an endless 



