ORGAN. 



screw, o, (fig. 3,) cut upon it to turn a 

 wheel, p, by the teeth cut in its circum- 

 ference ; this wheel is in the same piece 

 with a cylindric barrel, H H, shown se- 

 parately (in fig. 4, Plate II) ; it has a 

 great, number of short pins stuck in it, 

 which as it revolves upon its pivots, catch 

 the ends of a number of small levers call- 

 ed keys, r r r, and raise them ; this de- 

 presses the other, 1 1 1, ends, which are 

 attached to the rods, G, and consequent- 

 ly open the valves There are as many 

 of the levers, or keys, as there are 

 pipes, each answering to a different note 

 of the gamut ; the pins in the barrel are 

 so disposed, as to lift the keys in the 

 same order and time as any piece of mu- 

 sic for which the barrel has been previ- 

 ously made. The keys all turn upon one 

 wire, as a centre, and to prevent their 

 shifting sideways ; and by that means 

 missing the pins in the barrel intended 

 for them, they move in small notches, cut 

 by a saw in two pieces of brass plate, 

 which are screwed to the edge of a piece 

 of wood, K, and project below it ; the 

 wire which forms the centre for the keys 

 is also fixed to the piece of wood, K, 

 which is called the key-frame. A num- 

 ber of small pieces of mahogany are fix- 

 ed to the keys at t, and to these the rods, 

 G, are jointed by a piece of leather glued 

 to both : v v, are small screws going 

 through the key-frame, and touching the 

 piece of wood, t ; their use is to adjust 

 the levers, so that the ends, r r, shall 

 form one straight line. 



The key-frame is not fastened down to 

 the frame of the machine, but has a piece 

 of iron plate, w, fastened to each end, and 

 turning upon screws fixed to the frame 

 of the instrument, upon which the whole 

 key-frame can be fitted as a centre ; two 

 screws through its ends, resting their 

 points upon the frame, support it, and 

 by screwing these out, the whole frame 

 can be raised or lowered, to adjust the 

 ends of the keys the proper distance 

 from the centre of the barrel, H. 



By inspecting the plan and elevation, 

 (fig. 1 and J) it will be seen, that the 

 barrel is longer than the set of keys, by 

 the distance of one of the keys from the 

 other; the barrel can be moved along 

 endways this quantity, and for this pur- 

 puse it is mounted in a frame, (fig. 4) 

 which slides in a groove, shown in the 

 section (fig. 2) ; a small pin, P, (fig. 4) is 

 fastened to the frame, and comes through 

 the case of the instrument; it has notch- 

 es cut in it, which receive the sharp edge 



of a bolt, L, (fig. 7) fixed there, and 

 which holds the barrel in any place it is 

 set. By moving the barrel endways a 

 short distance, an entire new set of pins 

 is presented to the keys, r r, which pins 

 are disposed differently to the former 

 ones, and consequently play a different 

 tune ; there are often five different sets, 

 and as many notches, on the pin, P, (fig. 

 1.) Without some contrivance when the 

 barrel is moved endways, its pins might 

 catch some of the keys, and break or 

 bend them : to avoid this, the bolt, P, 

 which confines the barrel, and prevents it 

 being moved either way, is held down 

 by another bolt, R, (fig 7) sliding across 

 the end of it; this bolt has a pin fastened 

 to the back of it, which goes through 

 the case of the instrument, (marked x, 

 fig. 2 and 3) and when drawn back, 

 presses down the end of a lever y, 

 the other end of which lifts up the 

 key-frame, and thus raises the keys up 

 clear of the pins in the barrel, before 

 it can be moved endways to play another 

 tune. 



The regulator, D, is pressed down by 

 two wire springs, which equalize the 

 pressure upon the air contained in it, 

 when, by the bellows forcing in more 

 air than the pipes require, and conse- 

 quently it accumulates in the regula- 

 tor, it" lifts up its lid, ancl the handle 

 of a small valve, z, seen in the eleva- 

 tion, (fig. 1) is pushed against a part of 

 the frame ; this opens the valves, and 

 allows the air to escape, until the regula- 

 tor sinks by the action of the two wire 

 springs. 



From what we have said, a description 

 of the operation of the instrument will be 

 scarcely necessary. By turning the han- 

 dle, the crank, a, works the bellows, and 

 supplies the air to the pipes ; the end- 

 less screw turns the barrel, and its pins 

 lift up the keys at the proper time, opens 

 the valves, and admits the air into the 

 pipes. When soft music is to be played, 

 the stop, m, (fig. 2) which has a handle 

 coming through the case, is drawn out, 

 and the other shoved in ; this stops the 

 passages to the wooden pipes, and opens 

 the metal ones; for fuller music, the 

 stop, m t is pushed in, and n drawn out ; 

 the wooden pipes are then used, and, 

 for very grand and loud music, both 

 sets are used, by drawing out both 

 stops, and when both are in the sound- 

 cases, though the handle is still turned. 

 For changing the tune, the bolt, R, is 

 drawn back, this raises the key-frame , 



