_THE SOUND-BOARD._
WE may fairly assume that no one will embark upon the very serious
business of building an organ, and that probably no one will read this
book, who has not sufficient previous knowledge of the subject to
understand what is meant by the expressions sound-board, wind-chest,
pallets, sliders.
It may be taken as certain, moreover, that the reader who takes up this
book to assist him in the arduous work which he has undertaken, and
in the hope (which we trust we shall not disappoint) of finding rules
laid down in it which he can readily reduce to practice, has long ago
decided upon the position which the projected organ is to occupy, and
has measured with his eye, if not with his two-foot rule or tape, the
breadth, depth, and height which can be fairly allowed to the finished
instrument.
Great diversity of dimension and design is one of the peculiarities
which distinguish organs from all other musical instruments. Our organ
may be wide and shallow like a book-case, or it may be of little
greater width than its key-board, but deep like a wardrobe; it may
be carried up nearly to the ceiling of a lofty apartment, or may be
kept down to suit the low-browed rafters of a country farmhouse or a
workman's cottage.
The site chosen for the organ may allow of convenient access to the
back of it for tuning purposes; or it may compel us to arrange the
interior so that the back may always remain in close contact with the
wall. The projection of the keys, too, from the front, and therefore
the position of the player when seated at the instrument, possibly in
a small room; the place for the blowing-handle and for the person who
works it, so that convenient space may be left for him to fulfil his
irksome duty--these are matters of detail admitting of great variety of
treatment.
There are cases in which it may be possible, and very advantageous, to
separate the bellows from the organ which they supply, and to establish
them in an adjoining room, or beneath the floor or platform on which
the organ is placed.
All these considerations must receive full attention, and drawings or
rough sketches sufficiently intelligible to the workman himself must
be made in accordance with the decisions arrived at. Then, and not
till then, we can launch ourselves upon the very serious business of
designing and constructing the sound-board.
A serious business, we say, making a large demand upon our industry and
perseverance, and calling for adroit use of tools of several different
characters.
To facilitate our own task in describing the process of constructing
a sound-board, we shall divide this chapter into short sections, with
intervening remarks.
1. The sound-board is a shallow box, divided internally into as many
transverse grooves or channels as there are notes on the key-board.
The pipes stand upon holes bored through the top of the box into these
channels; and it is plain that if air is made to fill these channels,
and to issue from these holes in a constant stream when we please, all
the pipes which stand upon the holes will give their sounds according
to their pitch and character.
_Remark._--Thus if one channel, say the channel corresponding to Tenor
C, have five holes bored into it through the top of the box, then five
pipes standing upon those holes may be made to speak at once, or in
chorus, by pressing down the one key on the manual.
2. It is plain that we must possess the power of opening and closing
these holes in sets or classes at our pleasure, so that the air may
be directed into those pipes which we desire to hear, while others
are silent. The top of the box is therefore made double, or of two
layers of wood; and between the two layers long strips of thin wood
are introduced, lying lengthwise, that is to say, at right angles to
the channels beneath or within. The holes are bored down through all
these three layers of wood forming the top of the box; and we see that
by sliding the thin slip an inch or so to the right or left, we can cut
off at once the current of air from the pipes standing on those holes,
since the apertures in the three layers will then no longer coincide.
_Remark._--All this is quite independent of, and preliminary to, the
arrangements for admitting the supply of air to the channels themselves.
3. Having already made our Stopped Diapason pipes, let us range them
on a table or floor, and consider well how they must be planted on a
sound-board such as we are about to make for our organ, be it broad and
shallow, or narrow and deep, be it low or lofty.
_Remark._--No other stop will practically take up so much room on the
sound-board as the Stopped Diapason; hence, if we plot the board with
reference to it, all the other pipes will be easily worked in.
[Illustration: Fig. 5.]
4. On the opposite page several different plantations of the Stopped
Diapason are shown both in elevation and in plan. In Fig. 5 the pipes,
planted in a double row throughout, are placed alternately to the
right and to the left, meeting in the middle at the smallest pipe. The
exact reverse of this plantation, namely, placing the largest pipes in
the middle, and sloping down to the smallest pipes at each end, can
be easily imagined, and it is unnecessary to figure it. It is clear
that in both these plantations the large pipes occupy a space, as
regards depth, out of proportion to the space occupied by the upper
part of the stop. Fig. 6 shows a very common plantation of pipes,
which, as we shall see hereafter, allows us to simplify the internal
mechanism or action. Fig. 7, in plan only, shows a mode of economising
space as regards depth by planting the pipes of the lower octave in a
single row, resuming the double row at Tenor C. This plantation would
suit a wide and shallow organ. Figs. 8 and 9 show different methods
of planting the large pipes in order to avoid a disproportionate
sacrifice of space on the board. It will be seen at a glance that they
can be ranged behind the pipes of the tenor and treble octaves, or
carried off to the right and left in rows standing at right angles to
them. Fig. 10, in elevation only, shows how we may build an organ under
the ceiling of a very low room, by planting the eight feet octave on a
board of its own at a lower level than that of the sound-board proper.
And it is easy to conceive, without a figure, that this accessory board
may be replaced by two boards, to right and left, resulting in a plan
resembling that in Fig. 9, but giving a lower level to the tall pipes.
[Illustration: Fig. 6.]
[Illustration: Fig. 7.]
[Illustration: Fig. 8.]
[Illustration: Fig. 9.]
_Remark._--We confess to a strong liking for these later plantations,
which require some little careful mechanical adaptations, but result
in a compact arrangement, admitting of enclosure in a case of graceful
outline.
[Illustration: Fig. 10.]
5. We have still some considerations requiring careful attention before
we can map out our sound-board. The plantation of the pipes will be
the chief guide to the planning of the channels, with the divisions or
spaces between them; but it must not be forgotten that the boring of
the holes for the supply of air must be done in regular lines within
spaces or widths easily covered by the sliders. A slider is seldom
more than from 2 to 3 inches wide; there are good reasons why this
width cannot conveniently be much exceeded. But the feet of the large
pipes in the bass octave will be as much as 5 inches or more apart when
the pipes are planted back to back, as in Figs. 5 and 6. Hence we must
decide, before we begin to work, not only how the pipes are to stand
on the board, but how they are to get their wind and be deprived of it
by the action of a slider of the usual width. Perhaps we shall resolve
to run two narrow sliders under the foot-holes of the whole stop, one
for each of the two rows, controlling both sliders by a single knob
or handle. By this method every pipe will stand on its wind, as the
workmen say, that is, will be in direct and uninterrupted communication
with the channel when the holes are open. Or possibly it may suit our
plans better to run two sliders under the feet of the bass pipes, and a
third between them, under the rest of the stop; all three, be it well
understood, extending from end to end of the sound-board, but having
holes only at the proper places, and being blank elsewhere: these
three sliders being governed by one knob, or by two, if the stop is
to draw in halves (as it is called), that is, as a separate Bass and
Treble. Or, once again, we may use a single slider for the whole stop,
but carry the wind through grooves fashioned in the solid wood from
the holes bored in the usual way to the points at which the pipes are
planted. And, lastly, we may carry the wind from the holes to pipes
planted in any position, and practically at any distance by tubes made
of pipe-metal or other material.
_Remark._--It need hardly be said that an examination of the interior
of a well-built organ will be of great service to the beginner who is
planning his first sound-board.
6. The dimensions, then, and character of the sound-board having been
determined after full consideration of the site for the organ, and
a drawing or sketch having been made for your own guidance, proceed
thus:--Take a board of good clean bay-wood, 1/2, 5/8, or 3/4 inch in
thickness, and long enough and wide enough to form the "table" or
top of your work; and dress this carefully until one of its surfaces
is quite true and level. This dressed or levelled side is to be the
lower or under side, and we are about to form upon it the grooves or
channels of which it will ultimately form the roof. Next prepare a
ruler or straight edge of any thin stuff, and on this, with compasses,
rule, and square, guided by plenty of deliberate consideration, mark
the size and place of each of the grooves, and of the bar of wood
which will divide each groove from its neighbour, from end to end. You
will find, of course, and you were previously aware, that the widths
of the grooves and the thickness of the bars will vary in proportion
to their place in the scale. Let us say at once that 3/4 inch will be
ample width for the CC groove in our small organ; and let us advise
that the smallest groove in the treble be about 1/4 inch in width, and
that the bars between these narrow grooves be at least 3/8 or 1/2 inch
in thickness, in order to allow a good seat or margin for the pallets
or valves which are to govern the admission of the wind. In the bass
the bars will be very much thicker than this, or not, according to the
plan which you have adopted. The part of your rule in which you will
soon perceive that the chief danger of crowding your pipes will arise
is the tenor octave. Refer carefully to your pipes, and be quite sure
before you mark your ruler, that you are allowing room for Tenor C and
its neighbours to stand clear of each other when they are planted on
the completed board. Having satisfied yourself on these points, prepare
your bars from sound pine-wood, planing them with care, and especially
seeing that the edge of each bar is truly square with its sides. Two
inches will be an ample width for each bar, in other words, an ample
depth for each groove when completed. Their length will of course be
equal to the width of the table, less an inch or so, according to the
construction now to be described.
There are now two methods of proceeding. First method:--The table being
turned over, with the dressed side uppermost, your ruler well in sight,
with plenty of hot and fresh glue fix your first thick bar at or near
either end of the table. We say, "or _near_ either end," because you
may like to leave room for a finishing cheek of mahogany when all the
bars are put in. The second bar will be glued to the table in like
manner, the proper distance from the first being secured by "filling-in
pieces" of wood of the exact thickness, glued between the bars at
their ends. This alternation of bars and fillings-in will be continued
until all the grooves have been formed according to your ruler; the
rough ends of the bars will then be dressed with a sharp plane, and
neat cheeks of stout bay-wood will be glued on all the four sides of
the divided box which you have thus built up. Second method:--Prepare
the bay-wood cheeks first, and in the two long ones, using a fine saw
and small chisel, cut grooves to receive the ends of the bars. Form
a shallow box by gluing these bay-wood sides and ends to the table.
The corners need not be dovetailed, but an equally close joint must
be secured if dovetailing is omitted. Then introduce the bars, using
an abundance of hot glue, and taking care that no bar fits so tightly
between the cheeks as to risk bending. When all the bars are glued in,
add more thin glue within each groove, placing the sound-board in a
sloping position that the glue may run into the angles, and afterwards
reversing the board to the opposite slope, repeating the coating of
thin glue.
_Remark._--This unusual profusion of glue is to preclude the
possibility of air making its way from one groove to the adjacent one
bypassing between the edge of the bar and the table; and what is here
said applies equally to both methods.
We ourselves prefer the second method to the first. M. Hamel, in his
wonderfully accurate and minute treatise, describes a third, in which
the fillings-in are avoided. Those to whom his book is accessible
cannot fail to share the present writer's admiration of his marvellous
industry, and of his great gift of clear and precise description of
mechanical processes. Hopkins and Rimbault may also be consulted with
much advantage.
7. The work, thus glued up, must be left in a dry room for two or three
days, until all is perfectly set and hard. Meanwhile the other pieces
of which the completed sound-board will consist are being cut out and
prepared. We shall want the upper boards, the sliders, and the slips of
wood (_false sliders_ the French builders call them, while in England
they are termed _bearers_) which divide these from each other.
We may safely suppose that if the ordinary form of sound-board has
been chosen--such, for instance, as that which is shown in Fig. 6--its
size will be about 4 feet, or 6 inches more, in length. Its width will
depend on the number of stops for which it is planned, and therefore
of sliders which are to work on the table; if we are to have five
stops, about 15 inches may be taken as the probable width, but this may
be less, or more, according to the class of stops selected, and the
arrangement chosen for their bass pipes. To give accurate measurements
in feet and inches for all the parts of the sound-board would only
mislead our readers at this stage of our labours. We give general rules
only: it must rest with the reader himself, as we have now abundantly
reminded him, to decide on the shape of his sound-board and to make the
plantation of his pipes, and the consequent arrangement of grooves and
sliders conformable thereto.
Assuming, then, quite arbitrarily, and independently of all special
considerations, that the sound-board is 4 feet long and 15 inches wide,
we may cut out the upper boards from sound and clean bay-wood, 1-1/4
inch thick. Cut them 6 inches longer than the sound-board. And now as
to width. As there are five stops, and five sliders for them, are we to
understand that we shall have also five upper boards? To this we reply,
by no means. Our stops, we assume, will be two of 8 feet, two of 4
feet, and one of 2 feet. For reasons which we shall soon give, we shall
propose to have one upper board for each of these three divisions:
that for the 8-feet stops being 7 inches wide, that for the 4 feet 5
inches, and for the 2 feet 3 inches. Under the 7-inch board there will
be two sliders, each 2 inches in width; under the 5-inch, two sliders,
each 1-1/2 inch in width; and under the 3-inch, one slider, 1-1/4 inch
wide. The bearers will be thus:--The two outside bearers, that is,
those which extend along the front and back margins of the sound-board,
to be 1-1/4 inch in width; the second bearer (reckoning from the back)
to be 1 inch; the third to be 1-1/2 inch, because it will lie beneath
the line of junction, or rather of division, between the two wider
upper boards; the fourth bearer may be 1/2 inch only, being merely a
separation between the next two sliders; the fifth may be 1-1/4 inch,
falling as it does under a line of division; the sixth is similar to
the first. It will thus be seen that we have--
2 sliders, 2 inches each = 4 inches
2 " 1-1/2 " " = 3 "
1 " 1-1/4 " " = 1-1/4 "
3 bearers, 1-1/4 " " = 3-3/4 "
1 " 1-1/2 " " = 1-1/2 "
1 " 1 " " = 1 "
1 " 1/2 " " = 1/2 "
-------
Total width = 15 inches.
_Remark._--All this is so important that we have shown the measurements
drawn to scale in Fig. 11.
Cut out the sliders and bearers from perfectly clean sound bay-wood or
red cedar boards, not more than 3/8 inch in thickness. Having turned
your sound-board over, with the table uppermost, assemble all the
pieces, and satisfy yourself that your measurements are correct, and
that so far there is no error in your plans. See that all your planes
are in first-rate order, and set yourself in earnest to bring to a
perfectly level and true surface the table or top of the sound-board,
and one side of the sliders and bearers. No pains must be spared to
render the surface of the table absolutely true. Apply a "straight
edge" rubbed with chalk, moving it in various directions, and use
unwearied diligence in removing all inequalities detected by this
means. Take care, too, that there is no "winding." In short, adopt
all the means which the rules of good joinery give you for producing
a surface faultlessly level. This done, arrange upon the table, with
their planed sides downwards, your sliders and bearers, and pin them
down upon it with very small brads, piercing through near their edges.
In doing this have regard to the grain of the wood, as you are about
to dress the upper surfaces. Sink the brads well out of the way of the
plane with a punch, and bring the sliders and bearers to a true level
as you did the table.
[Illustration: Scale, two-thirds of an inch to a foot. Fig. 11.]
_Remark._--M. Hamel advises that in making the sound-board the table
should be left 3 inches longer at each end than the actual box beneath,
expressly to afford a bearing for the ends of the sliders during this
business of planing them. If this suggestion is not followed, the
projecting ends of the sliders will require separate attention.
The three upper boards may now be brought down upon the finished
sliders and bearers, and a couple of iron pins or dowels may be let
into each of them and into the bearers and table beneath, near their
extremities, for the purpose of confining them temporarily in the exact
places which they are to occupy. Dress over now the upper sides of the
three boards, which do not, however, require attention to absolute
truth.
8. We cannot yet bore the holes for the pipes. Before we can do so we
must prepare yet another board or boards of clean pine, 5/8 or 3/4 inch
thick, 4 feet 6 inches long, and 15 inches wide, for the rack boards
through which the pipe-feet are to pass, and which are to maintain the
pipes in an upright position. If you have two upper boards the division
should occur between those of the 8-feet and 4-feet stops. Pin down
your rack-board upon the upper boards with brads here and there near
the edges.
Let us now consider for a moment. We have made our box of fifty-four
transverse channels or grooves, and its top consists now of four layers
of wood--namely, the table, the sliders, the upper boards, and the
rack-boards. Through these four layers of wood, at the proper places,
are to be bored holes of various sizes clear through into the channels;
but it is plain that the holes in the rack-boards will always be much
larger than those in the three other layers, because the rack-boards
are to be ultimately raised about 5 inches above the upper board on
legs or pins, and will therefore receive the thick part of the conical
pipe-feet, while the holes in the upper board will only receive their
tip or small extremity. But the centres of the large holes in the
rack-board must coincide accurately with the centres of the small holes
beneath, and we shall therefore proceed to mark the exact spots where
each of the holes will commence.
By the aid of your marked rule, trace a line on the front and back
cheeks of the sound-board, showing the centre of each groove. From
these points draw lines across the rack-boards. It is evident that all
holes bored through the four layers of wood at any point in any of
these lines must terminate in a channel. Draw lines at right angles to
the last, showing the widths of the sliders and bearers; it will then
be further evident that we cannot easily get wrong in boring the holes
so that they may penetrate the sliders at the exact points intended.
But the actual boring, with certain consequences or contingencies
belonging thereto, must be reserved for the next chapter.