THE ORGAN IN THE NINETEENTH CENTURY.
Before proceeding further we propose to give a brief description of the
construction of the organ at the beginning of the last century and
explain the technical terms we shall use later.
As everybody knows, the tone comes from the pipes, some of which are to
be seen in the front of the instrument. The pipes are of various
shapes and sizes and are arranged in ranks or rows upon the
_wind-chest_. Each of these ranks is called a _stop_ or _register_.
It should be borne in mind that this word _stop_ refers to the row of
pipes, and _not_ to the _stop-knobs_ by the keyboard which operate the
mechanism bringing the row of pipes into play. Much confusion of ideas
prevails on this point, and cheap builders used to take advantage of it
by providing two stop-knobs for each row of pipes, thereby making their
instruments appear to contain more pipes than were actually there.
This practice was at one time very prevalent in the United States.
The early organ-builders to obtain variety of tone divided the pipes
into groups placed in various positions, each playable from a separate
keyboard, and this practice prevails to this day. An average church
organ will contain three or four wind-chests, each with its quota of
pipes and designated as follows:
1. The Great organ, consisting of the front pipes and other
loud-speaking stops. Back of this and usually elevated above the level
of the Great organ pipes is
2. The Swell organ, all the pipes of which are contained in a wooden
box with Venetian shutters in front, the opening or closing of which
modifies the tone; below the Swell box is placed
3. The Choir organ, containing soft speaking pipes suitable for
accompanying the human voice; and back of all or on the sides is
4. The Pedal organ, containing the large pipes played by the pedals.
Larger instruments have still another wind-chest called the Solo organ,
the pipes of which are very loud and are usually placed high above the
Great organ.
In some large English organs, notably that in the Town Hall of Leeds, a
further division was effected, the pipes of the Great organ being
placed on two wind-chests, one behind the other. They were known as
Front Great and Back Great.
The original reason for dividing a church organ in this manner seems to
have been the impossibility of supplying a large number of stops with
wind from a single wind-chest.
It will thus be seen that our average church organ is really made up of
three or four smaller organs combined.
The _wind-chest_ is an oblong box supplied with air under pressure from
the bellows and containing the valves (called _pallets_) controlling
the access of the wind to the pipes. Between the pallet and the foot
of the pipe comes another valve called the _slider_, which controls the
access of the wind to the whole row of pipes or stop. The pallet is
operated from the keyboard by the _key action_. Every key on the
keyboard has a corresponding pallet in the wind-chest, and every
stop-knob operates a slider under the pipes, so that both a slider must
be drawn and a pallet depressed before any sound can be got from the
pipes. The drawings will make this plain.
Fig. 1 is a front view and Fig. 2 a side view of the wind-chest. A is
the wind-chest into which compressed atmospheric air has been
introduced, either through the side or bottom, from the end of the
wind-trunk B. The pallets, C C C, are held against the openings, D D
D, leading from the wind-chest to the mouth of the pipes, by springs
underneath them.
[Illustration: Fig. 1. The Wind-chest. Front View]
The spring S (Fig. 2) keeps the pallet C against the opening into D.
The wires called _pull-downs_ (P, P, P), which pass through small holes
in the bottom of the wind-chest and are in connection with the
keyboard, are attached to a loop of wire called the _pallet-eye_,
fastened to the movable end of the pallet. A piece of wire is placed
on each side of every pallet to steady it and keep it in the
perpendicular during its ascent and descent, and every pallet is
covered at top with soft leather, to make it fit closely and work
quietly. When P is pulled down (Fig. 1) the pallet C descends, and air
from the wind-chest A rushes through D into the pipe over it. But the
slider _f_ is a narrow strip of wood, so placed between the woodwork
_g_ and _h_ that it may be moved backwards and forwards from right to
left, and is pierced with holes corresponding throughout to those just
under the pipes. If the apertures in the slider are under the pipes,
the opening of a pallet will make a pipe speak; if, however, the slider
has been moved so that the apertures do not correspond, even if the
pallet be opened and the chest full of air from the trunks, no sound
will be produced.
[Illustration: Fig. 2. The Wind-chest. Side View]
When the apertures in the slider are under those below the pipe, the
"stop," the handle of which controls the position of the slider, is
said to be _out_, or _drawn_. When the apertures do not correspond,
the stop is said to be _in_. Thus it is that when no stops are drawn
no sound is produced, even although the wind-chest be full of air and
the keys played upon.
This wind-chest with the slider stop control is about all that is left
to us of the old form of key action. The pallets were connected to the
keys by a series of levers, known as the tracker action.
There were usually six joints or sources of friction, between the key
and the pallet. To overcome this resistance and close the pallet
required a strong spring. Inasmuch as it would never do to put all the
large pipes (because of their weight) at one end of the wind-chest,
they were usually divided between the two ends and it became necessary
to transfer the pull of the keys sideways, which was done by a series
of _rollers_ called the _roller-board_. This, of course, increased the
friction and necessitated the use of a still stronger spring. That
with the increased area of the pallet is why the lower notes of the
organ were so hard to play. And to the resistance of the spring must
also be added the resistance of the wind-pressure, which increased with
every stop drawn. When the organ was a large one with many stops, and
the keyboards were coupled together, it required considerable exertion
to bring out the full power of the instrument; sometimes the organist
had to stand on the pedals and throw the weight of his body on the keys
to get a big chord. All kinds of schemes were tried to lighten the
"touch," as the required pressure on the keys is called, the most
successful of which was dividing the pallet into two parts which
admitted a small quantity of wind to enter the groove and release the
pressure before the pallet was fully opened; but even on the best of
organs the performance of music played with ease upon modern
instruments was absolutely impossible.