ORGAN. 
altered at pleafure, to bring it to the proper note it is 
perform when placed in the inftrument. This puioeaie of 
the cee is made by fliding the plug, D, up or dow 
the pipe 
A feétion of a metal pipe is fhewn in fig. 43 it is nearly 
the fame in operation as the wood pipe, though different in 
its conftruGion. Itisa cylindric tube, A B, formed of a 
mixture of lead and tin, caft in thin fheets and foldered up ; 
e pipe ; ne other third i is a Araigh edge, 
rather hae on the angle. F i nical pipe conveying 
the air to the pipe: eile upper ai “of this conical pipe 
bent to be parallel to the edge of the languid E, and a 
forms a {mall cleft, fimilar to the mouth of the — pipe 
for the paflage of the air. The lower end, B the cy- 
lindrical pipe is bent into the line of the cleft, to nae the 
current 0 e metal pipes are open at top, and are 
brought aun by enlarging or diminifhing the pipe at the 
top, and thus oe bulk ; a isa piece of — called 
the ear, foldere singer e pipe at eac cleft, 
he ftrea 
ipes this is not aprlied, and in the wood pipes its place 
1s fupplied by the edge OF the wood board forming the 
fide of the pipe, which is cut away. 
- There is another kind of organ pipes, which have a reed 
in the mouth; they are called trumpet ftops. One of thefe 
the found i 
r paffes into the tube D, thro oul a ae 
tube or mor a, which 3 is ftopped at the iowee end, but has 
an opening down the front, where it is made flat. It is fur- 
nifhed with a tengue, or flender brafs {pring b, which ap- 
plies to this flat fide and covers the opening. When the 
wind is impelled into the pipe A, it enters through the reed, 
againft the reed, determines the es th of the tongue, whic 
fhall have bert of free vibration ; ae by fliding 
this wire up or down ought to tu a 
e inftrument, 
eal o 
tuned in unifon with the diapafons, it 
ftrengthens the foundation, and fubdues the diffonances of 
the thirds and fifths of the fefquialtera, imparting to the 
ompound a richnefs and grandeur of effe‘t, adequate to 
the fublimeft fubjeds. 
he names 7 a ftops or fyftems of pipes ufed in this 
— are as 
Twelfth, a mecile ftop, fo oo from its being 
tuned twelve notes above the open diapafon, which will be 
merece hereafter. This ee on account . i pa or 
tuning, can never properly be ufed alone. n diapa- 
fon, {top diapafon, ae - cee on the be 
qualified to accommo t to the 
Stop oe a fto os ie Pipes oe which are A Sadie!) 
made of wood, and its bafe, up to middle C, always o 
They ‘are only half as long as thofe si he open 
diapafon, and are ftopped at the upper end with wooden 
ftoppers or plugs, which render the tone more foft and 
mellow than that of the open diapafon. AAs the pipes of 
rhe 
an) 
Sg: 2. atr: 
this ftop are of large fize, they cannot be contained in one 
row on the found board, they are therefore difpefed in two 
rows, and have two fliders, one for the bafs the other for the 
treble. 
Open diapafon, a oo ftop, which commands the 
whole fcale of the and which is fo called in contra- 
diftin@tion to the fo 
clofed at the top; 
aaa 
rives from the Goa of He pipes, being longer and {maller 
than thofe of other ftops. It is tuned in unifon with the 
diapafon, and equals them in compafs upward. 
Fifteenth, a ftop which derives its name from its pitch 
or {cale, being fifteen notes higher than that of the diapafon. 
This ftop and the twelfth, mellowed and em pores by the 
two diapafons and principal, form a proper compound for 
accompanying cheral parts in common choirs a parochial 
churches ve divided into two rows on the found board 
for bee and t eble. 
being thruft in m 
ach fide of the pupal 
keys, though ah two on each fide are hewn i in the on 
to avoid confufion: there being ten handles one is oeach 
of the fliders in the lower fet, as fhewn in fig. 1s ad their 
and properties have before been mentioned. The 
middie a of a fr is drawn by bent levers, as fhewn in 
m the _ horizontal arm o 
The finger-keys, O, P, are all baal fitted in a kind of fi 
or box, which flides in a a . 1.they are reprefented 
as drawn out to the full ae admit of being thruft 
i 
o, cf each key comes immediately beneath the end ef each 
of the rods Q, which are retained in their pofitions th pafling 
through holes in.a fixed rail extended acrofs the ke The 
parts of the organ being now fo fully explained, us is need- 
lefs to fay much of their mode of a@tion. ‘fhe wind cheft and 
foee cin are kept conftantly full ef air by the bellows, - 
