M U S 
the end 5, which thrufts up the end x of the lever, by the 
wire 5 x; this deprefl’es the end y of the lever, which pulls 
down the wire y V, and opens the valve V. 
A third way of opening the valve is this : At the end of 
the key b, is a lever 8, 9, moving in the centre 7. This 
makes, with the key, a compound lever. From the end 9, 
a wire goes to the valve. Now, the putting down the 
end 6 of the key raifes the end 8, which deprefles the 
end 9 of the lever 8, 9, pulls down the wire, and opens 
the valve. There is only one of thefe drawn in the 
fcheme, and but a few of the others, to avoid confufion. 
R, R, are the rollers, to move the Aiders, by help of 
the arms cf, cf, which are fixed horizontally in thefe 
rollers : he, he, are all'o levers fixed in the rollers; le, le, 
are the handles, which lie horizontally, and pals through 
the holes ll; they are fattened to the lever he, being mo¬ 
vable about a joint at e. 
Now, any handle Ip, being drawn out, pulls the end e 
towards l, which turns about R/c, along with the arm cf; 
and the end /pulls out the Aider fg; and, when p is thrull 
in, the arm cf likewife thrufts in the flider/g. 
Upon the feveral rows of holes which appear on the 
top of the upper board, there are fet up an equal number 
of rows of pipes. The pipes of an organ are of four 
kinds, flopped, half-flopped (with a funnel or chimney 
at the top), open, and reed, pipes. Various materials 
have been ufed for their conftru&ion ; but the moft com¬ 
mon practice is to make the flopped pipes of wood, and 
the open and reed pipes of a metal compoled of tin and 
lead. 
Figs. 3 and 4.. reprefent the front and feftion of a flop¬ 
ped wooden pipe. In fig. 4. a is a fquare block of umod, 
correfponding with the interior diameter of the pipe, 
upon which the back and two fides are glued. In this a 
channel is cut, in the direction of the flraded line, for the 
paflage of the wind, which, entering at the foot cl, paftes 
through the channel in the block, and the cavity of the 
lip or top piece b, and ftrikes upon the lharp edge of the 
front at e, the mouth : c is a movable wooden tompion, 
covered with leather to make it air-tight. When this is 
drawn outwards, the tone of the pipe is flattened, and, 
when puttied inwards, fliarpened. Figs. 5 and 6. repre- 
fent the front and feCtion of an open metal pipe. Fig. 6. 
cl is the foot, which is a hollow' cone, and is feparated 
from the cylindrical body of the pipe c, by a partition 
called the lenigue, or tongue, «, which anfwers the pur- 
pole of the block in the wooden pipe. The wind pafles 
through a narrow aperture at b, and ftrikes upon the up¬ 
per fide of the mouth at e. A fmall ear is ufually affixed 
on each fide of the mouth, for the purpofes of enriching 
the tone, and to tune fuch pipes as ftand in the ornamen¬ 
tal front of the organ. Metal open pipes are tuned by 
opening the tops with a brafs cone, to lharpen them ; and 
by doling them with the infide of the cone, to flatten 
them. Figs. 7 and 8. are the front and feCtion of an half- 
flopped pipe, or pipe a la cheminee. Thefe pipes are tuned 
by opening or doling the ears, which are made very large 
for this purpofe. Fig. 9. is the exterior of a reed-pipe, 
confifting of two parts ; the foot, a, and the tube or body 
of the pipe, b. The tube is foldered to a block of me¬ 
tal, c, (figs. 10 and 11.) which exaCtly fits into the upper 
end of the foot. In this is fixed a hollow demi-cylinder, 
cl, of brals, called the reed, flopped at the lower ex¬ 
tremity, and communicating at the other with the body 
of the pipe. The open fide of the reed (the edges of 
which are filed perfectly flat and parallel) is covered with 
a thin plate of hard brafs, called the tongue; one end of 
which is kept in its poiition by a fmall wooden wedge f, 
and the other left at liberty to vibrate with the aCtion of 
the wind. The degree of acutenefs or gravity of a reed- 
pipe, depends jointly on the length of the tongue and 
that of the pipe, meafured from the extremity of the reed 
to the extremity of the tube. It is, therefore, neceflary 
to have fome method of altering the length of the reed, 
Vol. XVI. No. 1118. 
lie. 369 
in order to tune the pipe. This is effefited by pulling up, 
or pulhing down, the wire-fpring g; which, preffing the 
tongue clofely againft the reed, ihortens or lengthens the 
vibrating portion of it. The degree of gravity, or acute¬ 
nefs, of any pipe, depends upon the length; mealured, in 
an open pipe, from the edge of the mouth to the extremity 
of the tube ; and, in a flopped pipe, from the edge of the 
mouth to the interior furface of the tompion. A flopped 
pipe is half the length of an open pipe of the fame pitch. 
We now return to fig. 1. where X reprelents a ftopped- 
pipe of wood, Z a flute-pipe of metal, Y a trumpet-pipe 
of metal, (landing in their places in the rows we have 
mentioned. The pipes, to prevent them from falling, 
pafs through holes made in boards placed upon the up¬ 
per board. The pipes are made to communicate with the 
wind-cheft in the following manner: There are holes 
bored that go through the upper and lower boards, and 
through the Aider (when it is drawn out), into the parti¬ 
tion below ; lo that any pipes placed upon thofe holes 
will then communicate with the partition, which, by its 
valve, communicates with the wind-cheft. But, when the 
Aider is thruft in, its holes do not anfwer to thofe in the 
upper and lower boards ; therefore, the communication 
is flopped, fo that no wind can get to the pipe. 
To every large organ there muft be at leaft two pair of 
bellows, which are marked in fig. 1. by T U, T U. O, O, 
are the handles, moving upon the axis nn, nn. Each of 
thefe bellows confifts of two boards, the loweft of which 
is immovable ; and in this there is a valve r, opening in¬ 
wards, and a tube leading to it, called the conveying tube. 
There is alfo a hole in this under board, from which a 
tube leads to the port-vent, which is a fquare tube 
marked 4, rifing upward, and inferted into the under 
fide of the wind-cheft at 2. In the tube leading to the 
port-vent, there is a valve that opens towards the port- 
vent, and fulfers the air to go up the port-vent, but not 
to return. Now the handle O, being pulled down, raifes 
the tipper board T, and the air enters through the valve r; 
and, when the handle is let go, the weight of the upper 
board, which carries three or four pounds to every fquare 
foot, continually defeending, drives the air through the 
port-vent to the found-board ; and, as the bellows work 
alternately, one pair is conftantly defeending, which oc- 
^cafions a continual blatt through the port-vent. 
The bellows are fliowm feparately at figs. 12 and 13. 
Single-bellows, for a chamber-organ, conlift of two ob¬ 
long boards, a b, ccl, fig. 12. connected at b by a joint of 
leather or web, and at the other three fides by thin folds 
,of wood joined together with leather. The lower board 
is fixed, the upper movable. In the low r er board, at ef, is 
an aperture covered with a valve (called by the organ- 
builders a pallet) opening inwards. At g is another 
aperture, covered with a hollow boxgr/, communicatino- 
with the wind-trunk; upon the mouth of which is an¬ 
other pallet opening outwards. When the upper board, 
a b, is raifed by prefling down the handle of the lever hi, 
the air enters the bellows at the aperture cf, and, upon 
letting go the lever, is forced into the wind-trunk at d, 
by the prefiure of weights placed upon the upper board. 
The pallet at cl prevents the return of the wind from the 
wind-trunk, when the upper board is raifed. Double 
bellows are made wdth three boards; a b, (fig. 13.) the 
rifer; ccl, the middle; and ef, the feeder boards. -At % 
in the feeder, is an aperture, and pallet to receive the air; 
at h, in the middle board, is the pallet of communication • 
and at i, in the rifer, the watte pallet, which is contrived 
to open, when the bellows are fufticiently full. The rifer 
empties itfelf into the wind-trunk at c. In old bellows of 
this kind, the rifer is connected with the middle board, in 
a manner fimilar to the Angle bellows ; but it is now ufual 
to join them with folds of an equal breadth in all parts, 
fo that the upper board, in rifing, is always parallel to 
the middle board. Thefe are called horizontal bellows, in 
contradiftinction to thole which.rife diagonally. Their 
5 B action 
