ORGAN. 
tn a flate any bey being preffed down admits the air to the 
Th 
) forming the front of 
Thefe valves, 
being saduelly opened the preffure of the foot, give the 
power of increafing the found, as the wind does the found of a 
an of bells, or fuppreffing it in like manner, by clofing them 
The fwellis fituated immediately behind the ornamental 
ie of the inftrument, which is in part only thin filk, ftretched 
in a frame to admit the paflage of the found. Each of the 
boards turns on pivots at its ends, and having fhort levers, 
which are connected together by a rod 39, they all open or 
fhut together. At the lower end of the rod is a {pring to 
fhut them clofe, and they are opened by a lever 40 within- 
fide, from which 2 wire defcends to the treadle before-men- 
tioned. ‘The {well produced a moft delightful effe& in fome 
mufic, giving the piano and forte to the organ, in a greater 
perfeétion than any other inftrument admits of, not even ex- 
cepting the violin. 
The mechanifm of the barrel comes now to be defcribed, 
for we have hitherto fpoken only of the finger-key. The 
feGtion ( fig. 1.) fhews that there are two rows of valves in the 
wind chelt. The afe of the firft fet at A has been Fully ex- 
t » mar ked 
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more particularly explained by the en 
barrel at figs. 6, 7, and 8. of Plate IV., 
tached from the eal Soe with all its mechamim. in in per pective 
but as the parts w intercept each other, if rae in flee 
proper oe oe and 8 a es efented as removed 
of the bare though i in reality thele parts all 
it. This is explained igs. to and 
11, the former ee an end view of the barrel and all its 
ea and fig. 11. an elevation in front fhewing its whole 
en in 
s, 4, are in miniature, the fame as the levers at N, 
(fg. 1. os ‘but their oppofite ends are operated upon by pins 
f the bar rel S, havin ng beaks, 
as the figures 8 fhew, upon which the pins operate in pafling be- 
neath them, to lift up the points of the keys: the pins in the bar- 
rel are fo difpofed as to lift the keys in the fame order and time, 
as any piece of mufic for which the barrel has pai previoufly 
. The keys all turn upon one wire as a centre of mo- 
tion, which is fupported by a wooden rail T, peters acrofs 
fr 
the inftrument. ‘To prevent the keys fhifting fideways, and 
by that means miffing the pins in the barrel intended for 
them, they move in {mall notches cut by a faw in a piece of 
brafs plate, which is {crewed to the front edge of the piece 
of wood T, and projecting beneath it: the wire, which forms 
the centre for the keys, is alfo fixed to the piece of wood T, 
which is called the key frame ; it is fupported at its ends on 
centre points, on which it rifes and falls asa centre of mo- 
tion, to lift the points of the keys clear above the pins of 
the barrel. Thefe centre points are made in plates of brafs at 
n, {crewed to the ends of the frame, and projecting fo as to 
bring the centre of ice to coincide with the joints at the 
ends of the keys 4, w ires, m, proceeding to the valves 
i, (fg. 1.) Thefe brats ee carry projeCting arms 1, which 
have {crews tapped through oe extremities, and the points, 
of thefe coming in conta& with fixed ftuds pro jecting from 
the frame, form refts for the bey frame; but t by turning ase 
{crews the diftance of the points of the keys from the barrel 
can be regulated at pleafure, that the keys may be pee 
lifted by the pins cf the barrel. 
a handle w, app ied to the 
peer enone and fhewn in P/. II. 
it carries a broad pinion, 4, engaging the teeth oe a ae 
wheel, 5, fixed on the extremity of the barrel. By this means 
the fame movement which, as before enone. blows the 
bellows, by the crank ¥y (fig. 1.) caufes the barrel to revolve 
owly, ‘The manner in which the barrel is made to play a 
variety of different tunes in fucceflion is thus: the {paces be- 
tween the keys 4, as fhewn in figs. 6 and 11. are fufficiently 
wide to ie eight rows of pins difpofed in them, therefore 
only one-eighth of the circles of pins are at once engaged 
with the keys, and by moving the barrel lengthways a {mall 
quantity, an entire new fyftem o pins are prefented to the 
i ae thefe are arranged to produce a different tune. 
rrel is ee ona frame of wood, which is re- 
peas detached in fig. 6 and 2 is 
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being drawn out, for the purpofe of changing the “barrel, 
and putting in a different one, but when flid bac 
olts. 
rames, 
tached to the woodwork es centres, on which they move fide- 
ve a 75 (fig. 6. pie . ‘be each frame, and es 
ted by a wooden a behind the barrel, which ther 
axis, LY in ufe it is coufined by pieces 
of i +9, moving horizontally o ges fixed to the 
ivots of the 
frame ms and preffin of 
barrel. The piece g is preffed by a cin behind it ; the other 
piece, 8, at the oppofite eid of the barrel, is {upport ted againft 
the circumference of a wheel 10, ( fig.7.) which is formed like 
a {nail, by continual variations of its radius. On ame 
fpindle with this {nail-wheel is another wheel, 11, divided on 
its edge with eight large notches, into which a roller at the ex- 
tremity of a detent, 12, adapts itfelf: the detent peng 
pufhed down by a ftiff {pring, always obliges the haba 2 
different tunes are played in fucceffion. The wheel, 12, is 
turned about by means of eight pins prujeGting from its 
furface, one anfwering to each notch ; thefe are prefled down 
by a catch 13, joined to a fhort lever. 14, projecting from an 
axis g, which allio carries two other levers, marked 15 and - 
the former of thefe has at the upper end a wire, 15, coming 
throuzh the frame of the orga n, and furnifhed with a knob, 
by pulling which the lever, ee is pes ca and the catch, 13, 
turning the wheel, 11, round one notch, fhifts the tune of the 
barrel, as before explained, Bue rho fome contrivance to 
raife up the key-fram n the barrel is fhifted, its pins 
might, catch (ous of the pots of the keys, and break or 
bend 
