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.

CHAPTER III.

THE DAWN OF A NEW ERA--THE PNEUMATIC LEVER.

Just as we no longer see four men tugging at the steering wheel of an
ocean steamer, the intervention of the steam steering gear rendering
the use of so much physical force unnecessary, so it now occurred to an
organ-builder in the city of Bath, England, named Charles Spachman
Barker,[1] to enlist the force of the organ wind itself to overcome the
resistance of the pallets in the wind-chest. This contrivance is known
as the _pneumatic lever_, and consists of a toy bellows about nine
inches lon