_THE ACTION._
THIS important subject will be prefaced by a few definitions,
superfluous, perhaps, for some readers, necessary for others.
_Backfall_. A lever of any clean wood, 3/8 inch or less in thickness, 1
inch or 2 inches in width, and seldom more than 1 or 2 feet in length,
turning upon a wire as its axis or fulcrum.
[Illustration: Fig. 27.]
_Bridge_. Backfalls occur in sets, corresponding to the number of keys
in a manual or of pallets in a wind-chest. They are arranged side by
side in notches formed by taking out the wood between saw-cuts in a
balk of mahogany or oak 2, 3, or more inches square. This balk is
called a bridge. Fig. 27 shows part of a set of backfalls and their
bridge.
_Square._ Squares are now usually of metal, but may be easily made of
wood, and consist of two arms, 2 or 3 inches long, united at a right
angle to each other, or cut at once from a single piece, and turning
on a wire as an axis passing through a hole at the intersection of
the arms. Like the backfalls, they may be arranged side by side in a
bridge, but the modern metal squares are screwed separately in their
places (Fig. 28).
[Illustration: Fig. 28.]
_Sticker._ A slender rod of light wood, not larger than a common cedar
pencil, and from a few inches to a foot or two in length (Fig. 29).
[Illustration: Fig. 29.]
_Tracker._ A flat riband of pine, sometimes several feet in length,
about 3/8 inch in width, and less than 1/8 inch in thickness. Trackers,
however, are now frequently slender round rods, like the stickers (see
Fig. 30).
[Illustration: Fig. 30.]
_Tapped Wires._ Formerly of brass, afterwards of tinned iron, and now
generally of phosphor-bronze or some other alloy. These are pieces of
wire about 3-1/2 inches in length, from No. 16 to No. 18 in gauge, and
cut with a screw-thread upon about half their length, with a ring or
hook at the untapped end.
_Buttons_. Round nuts of old and thick leather, or latterly of a
composition into which gutta-percha enters, pierced at their centre to
receive the tapped part of the wire.
_Cloths._ Little discs of woollen cloth, mostly red, used as mufflers
to prevent the rattling noise of wood against wood, or metal against
metal.
[Illustration: Fig. 31.]
_Roller._ An axis or shaft of light wood (but in certain cases of
iron), turning easily on two wires as pivots, which enter holes in
studs fixed firmly. The roller has two (or more) arms, 2 or 3 inches
long, projecting from it, generally near its ends. It is plain that
any motion given to the roller by acting on one of these arms will
be transmitted to the other arm. Rollers are in sets, like backfalls
and squares, and are arranged symmetrically on a board called a
roller-board (Fig. 31).
The nine articles just described are all brought together in the action
of an organ, even of a simple kind. We shall endeavour in this chapter
to show how they are combined in ordinary circumstances, involving no
peculiar complications.
[Illustration: Fig. 32.]
A simple and rudimentary example of the principle underlying all
systems of organ-action may be seen in Fig. 32. _a b_ is the key-board,
in which each key (as always in England) is balanced on a pin-rail near
its centre, and has a pin, _c_, passing through a little mortice cut in
it, while another pin, _d_, out of sight, near its fore end, keeps it
in its place, parallel to its fellows. At the tail of the key, _e_ is
a sticker, having a wire thrust into each of its ends, and projecting
about 1 inch; one of these wires is inserted in a small hole drilled
in the key-tail, and conical beneath, or cut into a little mortice.
A "cloth" is slipped upon the wire to prevent the end of the sticker
from rattling upon the key-tail. The upper wire of the sticker slips
into a similar hole (a cloth interposed as before) in the end of _f_, a
backfall working in its bridge, _g_. The other end of _f_ is connected
at once to the pull-down of the pallet by a tapped wire and button.
Clearly, if a finger is placed upon the key, its hinder end will rise
and will push up the back end of the backfall, which will draw down the
pallet; and by simply reversing the position of the backfalls as shown
in the cut, we may pull down the pallets in the wind-chest when placed
under the back of the sound-board.
If, then, we have fifty-four keys in the manual, a repetition of this
simple apparatus fifty-four times will be requisite to bring every
pallet, with the pipes controlled by it, under the command of the
player.
But this is taking no account of the fact that the pipes are not
planted in an unbroken chromatic series from bass to treble. In the
arrangement shown in Fig. 5 (and in its reverse or opposite plan) it is
plain that our simple backfalls would fail us; while in Fig. 6 some of
the bass pipes are planted to the right of the player, equally out of
reach.
Here we resort, then, to rollers. Fig. 33 shows a single roller, in
which _i k_ is the roller, turning on pivots in studs, and having arms,
_l_, _m_, of wood or of iron, projecting from it. The sticker from the
key-tail pushes up the arm _l_ when the key is depressed; the roller
turns on its pivots, and the arm _m_ pushes up the tail of the backfall
by another sticker, the pallet being thus opened as before; and it is
plain that by arranging a set of rollers on a board, as in Fig. 31, we
may act with ease upon pallets to the right and left which could not be
reached in any other way.
[Illustration: Fig. 33.]
The roller-board as here described is placed above the key-board,
with action by stickers; but it might be as easily placed immediately
under the wind-chest, with action by trackers. In this latter case,
the key-tail will push up the end of the backfall, the other end of
which will draw down a roller arm by means of a tracker; the other arm
of the roller will be hooked to the pull-down of the pallet by means
of another tracker. If so placed, room must of course be left for the
roller-boards by fixing the wind-chest at a sufficient height above
the backfalls. Figs. 34 and 35 show, sufficiently for our purpose, but
without any pretension to exactness of detail, the two positions of the
roller-board, and it is easy to see that by reversing the backfalls,
and in Fig. 35 the roller-board also, we can act upon a back wind-chest.
[Illustration: Fig. 34.]
Probably the reader has already surmised that the notches in the bridge
are by no means necessarily parallel to each other, or, in other
words, that the backfalls themselves are not parallel. The left-hand
pipes, as shown in Fig. 6, are reached by cutting the notches in
the bridge askew, so that while one end of the backfall is over the
key-tail, the other may be under the pull-down; and as this applies to
the whole set of backfalls, except those connected with the rollers,
the whole of the notches will be cut at varying angles to the central
line or axis, and the complete set of backfalls, when put in their
places, will present a fan-shaped plan. Hence it is sometimes called a
"fan-frame."
[Illustration: Fig. 35.]
But parallel backfalls occur constantly as transmitters of motion from
the keys to the rollers, and in other positions which will be noticed.
The plantation of pipes shown in Fig. 5, for instance, and the reverse
of it, which has the larger pipes in the centre, can only be adopted by
having a roller for every pallet; and in this case the backfalls will
be parallel, whether the action be by stickers or by trackers.
Already, we hope, we have given explanations so far intelligible that
ingenious reader's might have no difficulty in devising for themselves
some one of the numerous distinct combinations which may be made of the
nine pieces or members which we began by defining.
Let us take, however, the very common arrangement of Fig. 6 as that of
our organ, and apply to it the rules already laid down.
1. The keys will be procured, of course, from a maker, unless the
cost--fifty to sixty shillings--can be saved by adapting an old set.
We ourselves are admirers of the old-fashioned claviers with black
naturals and white sharps, or sharps of bone or ivory with an ebony
line down the middle of each. We possess two specimens of double
manuals of this kind; one of them, taken from an organ by the elder
England, is extremely handsome, with a mahogany frame almost black
from age, purfled like a highly finished violin. It was presented to
the writer many years ago by the late excellent builder, Mr. Walker.
The other double set, in a plainer frame, was bought at a sale for the
sum of one shilling and sixpence! The chief objection to the use of
old claviers is that the keys, from long usage or from original faulty
construction, rattle audibly against their guide-pins. This, however,
may be quite obviated by bushing the little mortices which receive the
guide-pins with fine cloth, as modern piano keys are bushed, or with
thin leather--for instance, the kid of old gloves. If the keys are
handsome, a little patience bestowed in this way may well reward the
operator, who will find the movement of his old manual when this is
done as silent as he can wish it to be.
2. We shall assume that the front board of the wind-chest is above
the keys, and that the organ is to stand against the wall. Hence the
backfalls will be turned towards the player, as in Figs. 32 and 34. But
all that we shall say will be applicable to backfalls acting on a back
wind-chest.
The keys, whether new or old, will probably be 18 or 19 inches in
length from their front edges to the rear. Their position in the frame
should be such as to allow the front edge to project 10 inches at least
beyond the front line of the wind-chest, in order to allow room for
a book-board; hence our backfalls will be short. But their shortness
will not be an evil, since the extent of their play or oscillation is
extremely trifling. One-third of an inch will be a sufficient descent
of the pull-down; the other end of the backfall will traverse a similar
space, and it will easily be seen how small an arc will be described by
any point near the centre. Backfalls from 4 to 6 inches in length will,
therefore, present no practical inconvenience. At the same time it must
be admitted that with such short backfalls the obliquity of those to
the extreme left will be somewhat embarrassing, and we shall recommend
the use of rollers for the six pallets to the left as well as those
to the right, especially since, as we shall show, the width of the
roller-board will not be materially increased thereby.
The backfalls should be of oak or mahogany, and the bridge of the same,
or other hard wood. If the bridge is not sufficiently strong and rigid,
a disagreeable and perceptible yielding of the whole manual will take
place when the player presses down a chord. The backfalls, if parallel,
or if only at a moderate degree of obliquity, will oscillate upon a
single wire extending throughout the whole range. This wire should be
sunk in a score or channel made with a =V=-tool before the notches of
the bridge are cut; and it should be held firmly down by small cross
slips of oak screwed with very fine screws into the wood of the bridge
between every six or so of the backfalls. This is much better than the
common way of driving in little staples of wire, which are apt to split
the wood, and are not easily extracted in case of repairs becoming
necessary. The small holes for such screws may be bored conveniently
with a drill, revolving by means of the Archimedean drill-stock, now
sold in all tool-shops for the use of fret-cutters.
Stickers may be quickly, easily, and neatly made by a bead plane. Take
a piece of three-eighth pine board of the requisite length and dress
it over. Then, with a three-eighth bead plane, strike a bead along one
edge, reversing the board when cut half through, and using the plane
as before. A slender wooden rod will be the result, which will only
require a little smoothing with glass-paper. To fit the wires into the
ends of the stickers, mark the centre of the rod with a punch or other
suitable pointed tool, and pierce a hole with a fine drill revolving in
the lathe. The wire may then be driven down without fear of splitting
the sticker or of entering it obliquely and penetrating the side of it.
For trackers we prefer round rods, made precisely as above, but with
a 1/4-inch bead. If tapped wires are to be inserted in the ends of
the trackers, it is well to flatten the inserted end of the wire by
hammering it, that it may not turn round in the wood when the button is
afterwards applied. A fine saw-cut is made in the end of the tracker,
the flattened part of the tapped wire inserted, and strong red thread,
well waxed, neatly tied round. The ends thus whipped are sometimes
varnished with a red composition. But this is superfluous.
If flat trackers are unavoidable, they may be cut from a three-eighth
pine board with a gauge, armed with a cutting-point instead of the
usual scoring-pin. A smoothing plane should be specially prepared by
fixing two slips of wood to its face. These slips will prevent the
plane from cutting anything thinner than themselves. Then, the plane
being held firmly down upon the bench, an assistant, walking backwards,
draws the tracker beneath the blade until it is reduced to the same
thickness as the slips, say 1/8 inch. The tapped wires will be inserted
and the ends whipped as before.
The squares shown in Fig. 28 are cut from thin boards of oak or
mahogany. Perhaps it will be found less troublesome and laborious to
make each square of two distinct arms, halved together and glued at the
angle, or more effectually joined by tenon and mortice. Metal squares
can be bought ready made, or they may be cut with shears from brass
plate. But we should use wood ourselves.
The rollers will be of pine or deal. They are cut out and dressed up as
square or rectangular rods of the requisite length, but two of their
sides are afterwards rounded or curved. It follows from this that when
arranged side by side on their board the curved sides may be nearly in
contact. As our rollers are short, three-quarters stuff will suffice
for them, but rods inch or more square should be used when rollers have
a length exceeding 2 feet or 30 inches.
Iron roller-arms have some great advantages, and they may be bought at
a moderate price per gross, neatly bushed at the holes to prevent a
rattling of metal against metal. But we ourselves deliberately prefer
arms of wood, involving, as they do, much greater labour. If these are
used, they should be made of oak or other hard wood, and let neatly
into a little mortice in the flat side of the roller. After they are
glued in, the holes may be pierced in each end of the roller to receive
the wires or pivots on which it revolves, and which should be stout and
rounded smoothly at the external extremity. One of the reasons why we
prefer wooden arms is this, viz. that the pivot can be driven into or
through the arm, which may thus be at the extreme end of the roller;
while if iron arms are used a margin or surplus must be left at each
end of the roller to allow room for the insertion of the pivot without
interfering with the arm, the screw of which passes through the axis of
the roller. But it is undeniable that iron arms abridge labour and save
time.
The studs in which the pivots are supported are also among the fittings
which can be obtained from the shops; but we have always made our own
of oak, turning the peg or shank in the lathe. These studs must be
bushed with cloth. Drill the hole truly through the stud, using a borer
much larger than the pivot-wire. Cut a strip of red cloth about 3/8
inch in width. Point one end of it, and draw it through the hole in the
stud. It will adapt itself to the circular hole, and will take the form
of a cloth pipe lining the hole, and effectually preventing a rattling
noise which would certainly be heard in its absence.
The planning of a roller-board, so as to economise space as much
as possible, is one of those operations which call for forethought
and ingenuity. The forms which it may assume are numerous; we shall
indicate by one or two simple diagrams some of the combinations of the
fan-frame with rollers which occur in ordinary practice.
Fig. 36 shows the usual way of carrying the touch to the pallets on
the right and left in the common form of sound-board shown in Fig.
6. A set of backfalls is assumed as _in situ_ under the wind-chest,
parallel to each other as regards the six pallets at each extremity,
but fan-framewise as regards the pallets from Tenor C to the top. As
the actual key-board (disregarding its frame) is about 2 feet 6 inches
in width, while the row of pull-downs on which it is to operate extends
to a length of 4 feet or more, we see that there will be an overhanging
margin or surplus of the wind-chest on each side of some 9 or more
inches, and it is probable that all the pallets affected by rollers
will be included in these overhanging portions of the chest.
[Illustration: Fig. 36.]
Take a piece of three-quarters or five-eighths board, the full length
of the wind-chest, and wide enough for your twelve rollers when placed
as we shall now direct. Dress it up, and give it two coats of priming.
At its lower edge mark the exact centres of the key-tails from end to
end of the key-board. At its upper edge mark the precise centres of the
tails of the twelve backfalls on which the rollers are to act, fixing
the board temporarily so that precision may be secured. Along the two
side margins of the board (which has been squared up true) mark rows
of dots at equal distances, say 1 inch or considerably less, according
to the scantling of your rollers, which may be placed as close to each
other as possible without actual contact when made to revolve through
a small arc on their pivots. You have now all the _data_ which you
require, and may draw pencil lines showing the exact place of every
stud on the board, the exact length of every roller, and the exact
spots on each roller at which the arms must be inserted.
Fig. 36, in which _x y_ is the key-board, the rollers and stickers
being represented by lines only, shows that the longest roller, that
of CC sharp, is placed by itself at the top. This is done in order to
enable us to use a single stud, common to two rollers, throughout the
board until we come to the last, which will stand alone. If the rollers
of CC and of its sharp were thus placed in a line, running into a
single stud, there would be hardly room enough for the latter, as the
arms would be in immediate contiguity. By giving the CC sharp roller
a place by itself, we get the following pairs: CC and DD sharp; DD
and FF; EE and G; FF sharp and A; G-sharp and B natural; A sharp will
have its own two studs. Thus we obtain a distance of fully 1-3/4 inch
between the centres of the contiguous arms of these pairs of rollers;
and if iron arms are used, there is room to drive in the pivot without
meeting with the interruption of the screw in the heart of the wood.
When these measurements have been made, and lines drawn in pencil or
chalk, the holes for the shanks of the studs may be bored, and the
board cleaned over and perhaps repainted. When the work is complete,
the cleanly planed rollers with their neat studs on the dark background
of the board should present a pleasing appearance.
[Illustration: Fig. 37.]
Sometimes the roller-board lies horizontally. It is then usually called
a roller-frame. Fig. 37 is a slight sketch showing how a roller-frame
may be united with squares in certain cases. _a b_ is a key-board,
acting by stickers on a set of squares, _c_, arranged in a bridge. _d_
is another set of squares in a longer bridge under the pull-downs of a
chest, _e_, let us say that of the second manual in an instrument of
considerable size, placed at the back of the case, and possibly some
feet from the player. _f_ is a roller-frame, transmitting the touch by
trackers to the extreme pallets right and left.
If economy of height is no object, however, the roller-board will be
placed between the squares _d_ and the chest _e_ in the usual vertical
position, or it may be above the keys.
Sometimes space is saved by inserting the roller-arms on _opposite
sides_ of the rollers, cutting apertures in the board through which
one arm of each pair may protrude. This plan may be regarded as a
compromise between the fan-frame and roller-board, the latter doing
duty as a set of backfalls.
[Illustration: Fig. 38.]
This arrangement is sketched in Fig. 38. The roller-board, _g_, is
above the key-tails, which act by stickers on arms brought through
openings in the board. The opposite arms, _h h_, in front as usual,
act on the pull-downs by trackers. We have adopted this plan in a very
small organ, and under the necessity of economising space as much as
possible, with complete success, although every pallet had its roller,
the fan-frame being entirely absent.
Rollers are often made of iron, especially in the case of pedal
movements, where space is not abundant. It will easily be understood
that iron tubes of small calibre, plugged with wood at the ends to
receive the pivots, and having iron arms screwed into drilled holes,
would present no serious difficulties to the workman, and might be
arranged upon a board little more than half the size of that required
by a set of rollers in wood.
We must not close this chapter without explaining that the plantations
of pipes sketched or indicated in Figs. 8 and 9 may be contrived
without grooving by an arrangement involving no serious difficulty or
complication.
[Illustration: Fig. 39.]
In Fig. 39, _a b c_ is a sound-board shown in section, divided
internally into two unequal parts by a longitudinal bar at _b_. The
front part, _b c_, nearest to the player, has 42 channels, and carries
all the pipes from Tenor C upwards. The hinder part has 12 channels
only, and supplies the bass octave. These two separate internal
divisions will have their pallets and springs as usual, and a single
wind-chest may include both sets of pallets, or two wind-chests may
be united by a short trunk, or separate trunks may be fitted to each,
at the discretion and convenience of the builder. We have now only
to adapt a set of backfalls in a fan-frame to the front pallets, and
a roller-board acting on twelve parallel backfalls to the pallets of
the bass octave, and we have a very compact and sightly arrangement
of pipes without a single groove, every pipe standing on its wind. If
the back pipes were these--Stopped Diapason, Bass, 4-feet tone, and
open Flute, wood, 4 feet; while the front pipes comprised a Dulciana,
Stopped Diapason, and Principal, or some equivalent--this little
instrument might be entirely satisfactory in all respects.
We may add that this arrangement of a double sound-board and wind-chest
has been successfully applied by the writer to an organ with two
manuals. The sound-board was about 5 feet 3 inches in length. The front
division had 84 channels, viz. 42 for each of the two manuals from
Tenor C to top F; the hinder division had 24 channels, viz. 12 for each
manual bass octave. There were practically eight stops, two of them
grooved to each other in the bass. Of this grooving, when there are two
manuals, we shall have something to say in a subsequent page. It is
not quite so simple an affair as the grooving already described.
When the key-board is in its place, the stickers adjusted, and the
keys levelled by attention to the buttons on the tapped pull-downs, a
heavy damper or "thumping-board" should be laid across the key-board.
In modern organs this is generally a solid bar of lead, about 1/2 inch
thick, and about 1-1/2 inch in width; it is covered with baize on its
under side, and a guide-pin, moving loosely in a little vertical groove
cut in the key-frame at each end, keeps it in position. Our damper may
be of oak or mahogany, very straight and true, and loaded with lead,
run when fluid into cavities made with a large centre-bit. The damper,
lying upon the keys, and supported by them, helps to keep them level,
and by receiving the blow or shock of each key, as the finger leaves
it, it prevents a tapping noise which might be heard if the rising keys
were stopped only by the board of the key-frame.
The descent or fall of the keys when pressed by the fingers should not
exceed 1/3 inch.