Organ. A wind instrument, the largest and most harmonious of instruments of this kind; for that reason, it has been given the name organ, óργανον, meaning instrument par excellence .

The invention of the organ is as ancient as its mechanism is ingenious.

Our churches only began using organs after St. Thomas Aquinas, in the year 1250.

The first one in France was given as a present to King Pepin by Constantine Copronymus, in 1267.

Two categories of parts can be distinguished in this instrument: functioning, and controlling. Each will be treated in the following description.

Description of the organ . The organ consists of a wooden cabinet, more or less richly decorated with carving, called the case ( see Case); two windchests, on which stand the ranks of pipes (of tin, lead or wood); and one or more keyboards. Wind is supplied to the pipes by several large bellows; it is conveyed to the chests by wooden conduits called wind-trunks .

From what we have said, it is clear that an organ is made of wood, tin, and lead, to which we may add brass for the reeds, and iron, which has two uses, as in all kinds of mechanisms.

Logical order requires that before describing the organ and explaining how it is built, we explain the preparation of the various materials used in it; we shall begin with wood.

Two kinds of wood are used in building organs , depending on the various uses to which they are put. To make wooden pipes, windchests, keyboards, and roller-boards, oak must be used, called bois d’Hollande because the Dutch trade in it. The best quality is never too good, especially for pipes and chests. The other kind of wood used in organ building is called bois de vauge ;  [1] this is also oak, but not as good quality as Holland oak. It is used to make the case and some parts of the organ that do not require first quality, such as boards for the bellows, etc.

The tin used in organ building is fine English tin, but lacking this, other grades may be used.

The lead is the common variety. These two metals are reduced to leaves or sheets as thin as required, in the following way.

Method for casting sheets of tin or lead to be used for making organ pipes. An oak table is built (Plate X, fig. 49), as long and as wide as necessary; it is made rigid by nailing several braces to the underside. The upper side must be perfectly flat, and it is covered with duck, well stretched and secured along the sides with tacks. Over this fabric, spread a less intact piece, or one half worn out, and the table is ready.

Next, make the casting box shown in [Plate X] fig. 60 . This is a box, ABCDEF , open at the bottom. Side AB of the box must not rest on the table, as seen in fig. 59 , showing the box in position on the table; and side EDCF must be higher, to compensate for the slant of the table, which is inclined more or less, as shown in the figure, by supporting it at one end on trestle G , and at various points along it by props or timbers HHI . To keep the table from sliding on its supports, it is secured at the upper end by rope K tied to it and to a hook set in the wall of the shop.

Once the table is ready and the casting box placed on it at the upper end, the edges contacting the table are given one or several coats of whiting diluted in water, to seal all the irregularities that may be left between the fabric and the edges of the box resting on it.

During all these preparations, the metal to be cast in a sheet is kept molten in an iron pot, quite similar to a plumber’s. If tin is to be cast, a little resin and suet are added to the pot, both to purify the metal and to refresh any part that may have been scorched; the molten metal is skimmed to remove the dross, and when it has cooled enough that it does not light paper on fire, it is dipped with a ladle and poured into the box, with a sheet of paper in the bottom to protect the fabric. During this procedure, a workman bears down on the box to prevent the weight of the metal from letting it flow before the box is full enough.

We know when it is time to cast tin in a sheet of when we notice that it is starting to granulate, little grains forming on the surface as if it were starting to set. Lead, on the contrary, must be cast as hot as possible, but without igniting a roll of paper dipped into it.

To cast a sheet of tin or lead, the box filled with molten metal is slid along the duck-covered table, while walking either backwards and pulling it, or forward and pushing it, and pressing down on the box. When it has reached the foot of the table, the remaining metal drops on the floor or into a trough placed beneath.

This procedure leaves the molten metal attached to the table in a sheet of a certain thickness, depending on the rate at which the box was moved, and the slope of the table.

Once the sheets are cast, they are left to cool. Next, the edges of the tin sheets are deburred of the many sharp points that otherwise would injure the workmen, and they are rolled up for use, as will be explained below. This is repeated until the molten metal is used up.

The largest sheets made in this way are 16 feet [2] long and 3 feet wide, or only 18 inches. If the pipes are of two pieces, as is usual when they are of a certain size, it will readily be understood that the table and the box must be of suitable dimensions.

When the duck covering the table is fresh, the sheets cast on it are usually defective, either because the dampness in the fabric causes little bubbles, or because the fibers of the nap have the same effect, and the sheets must be cut up and returned to the pot.

Once the sheets are cast, as we have said, they are forged and planished on a block with a hammer, shown in [Plate X] fig. 62 . This hammer is round, with one face flat for planishing, and the other one slightly convex for forging. These two operations harden the metal and make it stiffer and better able to keep the shape it is given for use. It will also be found that tin is very hard to forge, while lead is very soft.

Once the sheets are forged and planished, they are laid on a workbench that must be very smooth, and flattened with a beater. ( See Beater, and [Plate X] fig. 65 .) Thus flattened, the sheets are burnished with a steel burnisher, [Plate X] fig. 64 . See Burnisher. After this procedure they are completely finished, although the tin sheets require further work. After they are flattened out on the bench with the beater, they are planed with a plow ( See Plow, and [Plate X] fig. 63 , illustrating it.) The plow is a plane with an iron sole and a blade that is almost vertical. The reason for this design is that if the blade stood at an angle, it would cut too deeply and leave holes; while it must scrape somewhat firmly and take light shavings. This procedure evens the thickness of the sheets, and it is finished using a joiner’s scraper ( See Scraper.) This procedure is done on both sides of the tin sheets, while the lead sheets are planed only where they are thicker. The planed side of a lead sheet is always turned towards the inside of the pipe.

Note that for planing tin, the sole of the plow is lightly greased, while with lead, water is applied, and often: the wetter the lead, the larger the chips planed away.

After all these operations, the tin sheets are polished in the following way. Take water and soap; put water on the sheet and rub it with soap. Then burnish it with the burnisher, which must be well polished. For this purpose, a pine board is coated with tin oxide and oil, the burnisher is rubbed on it until it is well polished, and it is wiped with a piece of serge. Then it is rubbed over the entire surface of the sheet.

When the sheet is burnished overall, whiting is crushed and scattered over it, then it is rubbed with a piece of serge until it is bright; then the polishing is complete. It goes without saying that only the surface that will be the outer side of the pipe is polished, for polishing the inside would be wasted effort; indeed, only the tin intended for façade pipes is polished, the ones that show.

The brass used in organ building is in the form of plates of various thicknesses, and wire.

Iron is used for roller arms and various other purposes that we shall explain below, in specifying the materials used for the various parts of the organ .

After discussing the materials that make up an organ and explaining how they are prepared, we shall set forth their uses, while explaining the various parts that constitute an organ .

The organ case, [3] or cabinet, is built of either Vosges or Holland oak, and is divided into several parts. The round projecting parts, IN , [Plate] I, are called towers ; the flat parts, KLMN , are called flats . Their shape and size are arbitrary, as varied, in fact, as there are organs in the world. Note, however, that the number of towers must be uneven; one is placed at the center and one at each end. The case is decorated with as many carvings as desired, like figures, stelae, or caryatids supporting the towers on their shoulders or their heads, groups of children placed atop the towers, holding various musical instruments as if playing on them, in short, all the various ornaments that can be imagined, in keeping with the location where the organ is to be placed. The case shown in Plate I is one of the plainest that can be built, but we have chosen to make it this way rather than loading it with ornaments because it is better suited to our presentation. That is also the reason why we have shown it cut in half: to show some of the inner parts of the organ .

In large church organs , in front of the case there is usually another case or small organ , called a Positive , to distinguish it from the other case, called the Great Organ . The Positive usually has three towers, and the Great Organ five, seven, nine or more; if so, the Positive has five. In Plate I , CDFE  [4] shows the floor plan of the Positive and its location relative to the Great Organ ; the organist is seated between these two cases.

In churches, organs are located in a high place, for example on a gallery, and the Positive projects over the gallery rail.

Behind the front of the organ case are located two windchests, abC , [5] above which there are rackboards, defg , with as many holes as there are on the chest. These holes, which receive the feet of the pipes that stand on the chest, hold them all in a vertical position. See the article Windchest, where the structure and function are explained in detail, and [Plates II and III] figs. 2 through 14 , showing all their aspects. Here we shall only say that channels or grooves KL [Plate II] ( fig. 2 ) are horizontal, perpendicular to the front of the organ case; that sliders MN [Plate III] (fig. 10) lie at right angles to the channels, and consequently parallel to the front of the case. The number of channels is equal to that of the keys in the keyboard; thus, if an organ has two, three, four, five keyboards, the number of channels is the same, and they are located in the case as we shall explain below.

Keyboards . Organ keyboards usually have only four octaves, to which a high D and a low A are sometimes added. See the article Keyboard, which explains their making and use, and [Plates IV and V] figs. 15-19 .

Rollerboards . The keys are connected to the chests by rollerboards, so there are as many of them as there are keyboards. See Rollerboard. There is none for the Positive chest and keyboard, which are connected by backfalls, which for this reason are called backfalls of the Positive and stickers ( See these articles); or for the cornets, which are usually connected by compound backfalls. See Compound backfall.

The rollerboard for the Great Organ is located inside, between the keyboard and the windchests: the board is mounted inside the front of the case, so that the trackers from the rollerboard down to the keyboard and those from the rollerboard up to the windchest are all in the same plane and parallel to the front of the case. The rollerboard for the pedals is located between that keyboard and the one for the great organ ; sometimes it is in two parts, the rollers controlling other rollers that are connected by trackers or wires to the pallets of the pedal chests.

The wind from the bellows ( See Bellows) is brought to the pallet boxes of the windchests by large wooden conduits called wind trunks . The wind can only escape when a key is depressed, opening a corresponding pallet; then it enters the channel in the chest. However, it will not sound any pipe if none of the registers receives wind. So we see that a mechanism is required to open or close the sliders at will. This mechanism is called drawstop action ( See Drawstop), although there are many other moving parts in the organ .

We must observe that the pipes standing on a chest are arranged in two directions: one, along the sliders: the series of pipes taken in this direction is called a stop , and there are as many of them as there are keys on the keyboard. The series of pipes taken along the channel has only one pipe for each stop; thus, the same channel has all the Cs of the various stops, another channel all the Ds of the various stops, etc.

We have seen how the wind brought from the bellows to the pallet box enters a channel; now we see that it will sound only a single pipe of a single stop if only one slider is open; it will sound two pipes in two different stops if two sliders are open, and so forth.

The making of organ pipes . First, stops made of wood . All the wooden pipes that are found in the organ are alike: they only differ in size, which is determined by the scale ( See Scale). A wooden pipe like the one shown in [Plate VII] fig. 30 is composed of four boards of Holland oak joined with tongue and groove, as shown in [Plate IX] fig. 52 . The four boards are securely glued, and of a thickness proportional to the size of the pipe; they must be exactly square inside, and the lower end is closed with a square piece of wood, 2 2 [fig. 30, no.2] , bored at the center to receive foot A , which is called a counter-bevel because it is opposite the languid C , which is another board that closes the foot of the pipe and is beveled downward, as the figure shows. Part 3 is called the lower lip , and the small gap between the languid and the lower lip is called the windway . Opening 3 4 between the lower lip and the beveled upper lip, 4 5 , is called the mouth ; its height must be one-fourth the width at b b ( fig. 30, no. 1 ). The upper lip is defined with two saw cuts, xy xy , decreasing in depth from y to x ; the extra wood is cut away with a chisel, so that lip bx xb is a perfect square, and it is beveled from 5 to 4 , as the side view shows. This procedure is done before the pipe is glued. The stopper, EF , is a square of wood covered with sheepskin with the hair side out; it has a handle, F , allowing it to be raised or lowered readily, for tuning.

Now we must explain how sound is produced in pipes, both open and stopped; we shall start with open pipes, assuming only that sound consists merely of elastic undulation in the air, as is universally recognized; that air is a body that can be more or less condensed; and that it has inertia. See the article Air. The air expelled from the bellows is loaded with their whole weight; it enters pipe DE [fig. 30, no. 2] through toe A standing on the chest, it enters chamber B , then exits through windway 3 c . Then it is divided in two: one part leaves the pipe and escapes at F , and the other enters the pipe and goes from D to E , where we assume the pipe is open.

The air coming from the bellows is much more condensed than outside air because of its elasticity, and it tries to expand in every direction, but it can only do so through toe hole A , so it exits through this opening and meets the air contained in chamber B , which it condenses in turn; it tries to return to its former state, but it can only exit through the windway in a very thin sheet, which expands after exiting and strikes the upper lip, where it divides, as we have said above. This air movement may be considered an infinitely rapid series of explosions, according to the articles Weak tremulants and Strong tremulants, to which we refer in this connection, as well as below concerning the formation of sound in reed stops.

Thus, the air that enters the pipe does so in little shocks or explosions, so it strikes the air in the pipe in the same way and condenses it to a degree. This air resists through its inertia until, in its effort to return, its mass towards E , where we assume the pipe to be open, no longer resists enough to let it condense further; then the air suddenly explodes through the opening of the pipe. This explosion is followed by another one, the sooner the shorter the pipe, since the mass of air contained in the pipe, that resists through inertia, is smaller. This is why the largest pipes give lower notes than small ones, since we know that the only difference between them is the frequency of their vibrations in a given time.

As to stopped pipes, we observe that they sound the octave, or almost the octave, below the pitch they would have if they were open. We shall assume for now that they sound exactly the octave below; then we shall explain why the difference is not exactly an octave. It is clear that the pipe can only speak through its mouth, since its upper end is stopped; that is why the mouth is so named.

Those who have attempted to explain this phenomenon have simply said that since the air circulating in the pipe has twice the length to travel, the pitch must therefore be lower by an octave, by analogy to a string, which being twice the length at the same tension, goes down an octave. See Monochord. But since they did not explain why a string of twice the length at the same tension sounds an octave lower (an analogy, which in physics is no conclusion), and since it is not clear why, because the air in the pipe travels twice the distance, the pitch must go down an octave, their explanation is therefore defective, the more so because we know that differences in pitch from low to high are caused only by the frequency of vibration in the elastic parts of the air. We shall attempt to explain this phenomenon, following the principles we have established while explaining the generation of sound in open pipes.

The air condensed by the bellows divides evenly on leaving the windway: one part enters the pipe, and we shall consider only this part: it condenses its portion of air and pushes it towards E, where it encounters an insurmountable obstacle: the stopper closing the pipe. When condensed as far as possible, given its inertia and the obstacle that keeps its explosions from exiting the top of the pipe, this air reacts with the air condensing it and pushes it back towards the mouth of the pipe. However, since in elastic bodies compression is equal to expansion, as explained in the articles Elasticity and Spring, it follows that the explosions of the air contained in the pipe must be half as frequent; therefore, the pitch of the pipe will be lowered by one octave.

However, we observe that stopped pipes do not go down exactly an octave below their pitch when open; the interval of the open and stopped pitches is always less than an octave. This is the second part of the phenomenon that remains to explain.

This effect has two causes, the first of which is certain. The first is that the path traveled by the air in the pipe from where it exits the windway to its exit from the mouth of the pipe is not exactly twice the path from the windway to the stopper, because the air brushes against the upper lip of the mouth: the distance is double, less the height of the mouth, and consequently the pitch will not be exactly an octave lower.

We need not insist that the air travels twice the length of the pipe, as we pretend to believe, once we have established the contrary, but since elastic force can be taken for granted, after the elastic body has traveled a certain space at a certain speed, this assumption is allowed.

The other cause of this effect, which we have called less certain, is the speed of the wind, which is much less in stopped pipes than open ones, but it seems that this cause ought to produce the opposite effect: since the air in the pipe is condensed more slowly, it seems that its explosions should be less frequent, which would lower the pitch more than an octave. Perhaps the observed effect is only the result of greater force in the first cause, explained above, than in the second; this may well be elucidated by experiment.

We shall explain the production of sound in reed stops after explaining how they are made.

We have seen how wooden pipes are made; now we shall see how those of tin and lead are made.

The sheets of tin or lead are laid out on the bench and cut to the size and shape required. The pieces for the body of the pipes are rectangles, AB 3 4 [Plate VIII], fig. 31.1 . The lower edge, 3 4 , is to form the bottom of the pipe; it is divided into four equal parts,  [6] at points 1 and 2 , and the two center parts, 1 x and x 2 , are each divided equally at points b c . A perpendicular is raised, x y , on which a x must equal one-quarter plus one-eighth of the width 3 4 , which is the circumference of the pipe, or the distance 6 2 . [7] Taking point a as center, and a radius one-eighth of width 3 4 , arc m y n is drawn, forming the upper part of the upper lip. Then the two perpendiculars are dropped, mb and nc . See the article Mouth and Pointed mouth. Next, the pipe is rounded on a wooden mandrel if cylindrical, or a wooden cone if the pipe has that shape; it is rounded by striking the tin or lead with a beater, so that the two edges, A3 B4 , meet. Once the pipe is rounded, the mandrel is withdrawn, and the pipe is coated with whiting inside and out. See Whiting. It is scraped with a pointed scraper, and it is soldered. See Solder.

When the pipes are large, like those in a 16’ Montre, they are made in two pieces, each as long as the pipe and as wide as half its circumference; this way the tin sheets are only cast to the required width.

After the pipes are soldered, they are rounded a second time, so that they have no bumps; this is rather difficult, especially for tin, mainly when the pipes are heavy and large. As for small ones, they are rounded while holding them in the hand, turning them on the mandrel held between the knees or mounted on the bench with a hold-down, and tapping them with a light beater.

When the pipe bodies are ready, their feet are formed [Plate VIII], fig. 31.2, c d e . The pipe foot is a more or less elongated cone, whose circumference is determined thus. On a sheet of tin or lead, according to the material of the pipe body, an arc is drawn which if straightened would be equal to the circumference of the pipe. The radius of the circle is side e d of the cone, which is to be the foot. From the center of the arc already mentioned, two radii are drawn, one at either end; the sheet is cut along these lines, leaving a sector of a circle, which is the cone flattened out; it only needs rounding on a conical mandrel, it is coated with whiting and soldered, as for the body of the pipe.

Although the length of the feet is quite unimportant, care is taken with display pipes to make the feet of symmetrical height and proportional to the length of the pipe, which makes their appearance more pleasing, as we shall explain when speaking of the façade. After the foot is rounded, the lower lip of the mouth, a , is drawn, an arc of about 60 degrees; the segment formed by this arc is brought to the inside of the pipe, so that after it is flattened it forms a chord at the base of the cone or foot. [8] This chord must be equal to a side of a square drawn within in the circle of the base, so that viewing the cone from this side, it has the shape of a D [lying round side up].

Once the pipe foot has been made, the languid, a D [fig. 31.3], is soldered to its base; it has the same shape as the letter D, a large segment of a circle. The languid is soldered along its circular portion only; the chord of the segment aligns with the lower lip, leaving between them a narrow slot we have called the windway . This slot is the path of the wind from the bellows into the body of the pipe. Then the body is soldered to the foot, and the pipe is completely finished.

When lead pipes are stopped, a plate of the same metal is soldered to the top of the body, so it is completely closed. See Plate, and [Plate VIII] fig. 32 B , showing a pipe of this kind. Chimney pipes only differ from these in having a small tube of the same material as the pipe, usually lead, soldered to a hole in the center of the plate stopping the pipe. See Chimney, and [Plate VIII] fig. 32 c , showing a chimney pipe.

These two kinds of pipes always have ears, whereby they are tuned. See the article Ears.

The length and diameter of the pipes are determined by the scale. See Scale. The higher the pitch of the pipe, the shorter it is, as explained in the article. An organ is designated by the length in feet of its longest pipe, sounding C two octaves below middle C . Thus, an organ is called 32-foot when that pipe is 32’ long, 16-foot when it is 16’ long, 8-foot when it measures 8’, and 4-foot when it is 4’. These are all the designations that can be given to organs .

Making reed stops. All reed stops are alike where the reed is concerned; they differ only in the shape and size of the pipe. We shall explain these differences after we have explained the making of reeds. A reed has three principal parts: the reed itself, designating the three parts we shall discuss: the tongue, the wedge in the block, and the tuning wire. See the individual articles .

The shallot is a half-cylinder of brass closed at one end, shown in Plate IX, fig. 53, A and C . The shallots are given their shape by stamping them in a die. See Die, and fig. 54 , which shows it. The tongue, shown at B in fig. 53 , is a small strip of very thin, elastic brass, laid against the surface of the shallot so as to close the entire opening. These two parts are inserted in hole A in the nut; the nut has a shoulder that maintains the shallot in a vertical position. The nut is of lead, cast in a two-part brass mold in which a peg is placed to make the hole during casting, which spares the effort of boring it after casting. Care is also taken to make a small hole through the nut opposite the shoulder, to insert the tuning wire, as shown in fig. 44 and fig. 53 A , where the dot represents the hole for the wire. The rest of the space left in the center hole after the shallot is inserted is filled with a small wooden wedge, D , of conical shape. This wedge is half of a cone cut along its axis, with its triangular side placed against the tongue and its conical side against the hole, so the opening is completely closed; this has the added advantage of stabilizing the shallot and tongue on the body of the nut.

The pipes for reed stops are all conical in shape except the Cromorne, and they are usually of tin. Their construction is the same as for the mutation [flue] stops explained above, except that they are rounded on a conical mandrel.

Before the shallot is assembled to the nut, the latter is soldered to the toe of the pipe, which is always the apex of the cone; to the body of the pipe is soldered the ring, fig. 44 D ( see Ring), whose purpose is to act as a guide for the tuning wire, which runs through a small hole in the ring, as shown in the same figure. When the tuning wire is installed, the pipe is completely finished.

The tuning wire is a wire bent as shown in fig. 53, Ff . Part f of the wire bears against the tongue, fig. 44 , so that raising or lowering the stem of the wire slides part f along the tongue; this movement is what tunes the reed.

The lower end of the pipe, CD , fig. 44 , is inserted in a boot placed beneath it, see Boot.

The boot is made like the mutation pipes: a cylindrical body, A , and a conical foot, B , with a hole like all pipe feet, stood on the chest to receive the wind and convey it to the reed. It will be easily understood that the boot must fit exactly to the ring on the pipe, with no gap, otherwise the wind coming from the chest to the boot would escape through the gaps instead of going through the reed, and not return to the conical part of the boot, if the ring did not fit the walls of the boot exactly.

One point to treat with care is to make sure the tongue, elastic as we have said, does not touch the shallot at the lower end when it is not compressed: it must be a very slight distance from the shallot.

Having explained the construction of reed stops, we shall now show how sound is produced in this kind of pipe, using the principles established above. The condensed air, or wind, pushed by the bellows into the chest, enters the boot of the reed pipe through the hole in the toe; the boot may be seen as analogous to the chamber of a wooden pipe: the wind is compressed and tries to escape in every direction, but it can only do so through the reed, since as we have said the boot is tightly closed. Therefore, it will further open the reed by raising the tongue, followed by an explosion of the air contained in the chamber or boot; but since the tongue is elastic and has been moved from its point of rest, it will try to return; after returning, it will continue until it meets the surface of the shallot, since we know that elastic bodies held by one end oscillate like a pendulum. The instant the tongue meets the shallot, the air constantly entering the boot will condense again, but at the same time the tongue will lift from the shallot, returning to rest by its elastic force; there will be a second explosion, and the tongue will be raised as the first time, then its elastic force will return it to the shallot. So on in alternation, and the more frequently as the tongue is shorter or more elastic, or the wind stronger. This effect is the same as the tremulant, which may be considered a reed without a pipe. See Strong tremulant.

Thus, we see that the sound of the pipe depends on several variable causes. This is why no one has yet given accurate scales for reeds, for not having discerned the three causes of a single effect. We shall attempt to give a reliable rule for determining the scale, assuming the last two causes are constant.

Draw line AB [Plate IX], fig. 50 no. 2 , at will, divide this line into as many parts as there are keys in the keyboard, or pipes in the stop for which you are seeking the scale. From the division points drop perpendiculars and at their feet mark them C, D, E, F , etc., following the sequence of keys.

Next, make a shallot of suitable length and diameter, and fit it with a suitable tongue; raise or lower the tuning wire until the sound is as resonant, full and pleasing as possible, without concern for the pitch. Having found that pitch, find its unison on the harpsichord: it may be G in the bass octave. Take down the pipe without disturbing the tuning wire, and with dividers carefully measure the distance from the wire to the tip of the tongue, the length of the vibrating part of the tongue; transfer this to line Ea , which I assume to be the perpendicular corresponding to G , and mark it off.

Next make another shallot, but much smaller, assemble it with a tongue and make it speak as well as possible, as said above. Find its unison on the harpsichord, say E in the upper octave, carefully measure the length of the vibrating part of this tongue, and transfer it to the corresponding perpendicular, which I assume to be Fx , and mark it. Using the two marks, draw line CD across perpendiculars Ea and Fx , intersecting the other perpendiculars at y y y y etc. The portion of the perpendiculars between the feet and line CD will be the length of the vibrating part of the reed tongues that will give the pitches corresponding to the notes represented by the perpendiculars. This method is surely ingenious, and as precise as something can be where incommensurate physical causes combine to produce the effect; an example is the elasticity of the tongues, where it is very difficult to obtain uniformity.

The variations produced by this cause are sometimes so substantial that a reed may give a note that is much lower than that of another reed, although its reed is shorter, and according to our scale it should be quite the opposite. In this case, the best remedy is to reduce the thickness of the tongue, or replace it with another, if it defies all correction. It should be certain that a reed stop will be perfect as long as it follows exactly the scale we have set forth.

The proportional diameters of the shallots are found thus: mark on perpendicular aE the diameter of the shallot that gave that measurement, and the diameter of the other shallot on perpendicular xF ; draw line CD through these points, intersecting the perpendiculars at points giving lines taken as diameters of the corresponding shallots. Finally, add to each one a suitable length for adjusting the tuning wire and seating the shallot in the nut.

When reed pipes are large, they are made in two pieces: the lower one, which holds the large one, is call the tube ( see Tube). This arrangement neither diminishes nor increases the quality of the pipe; it is simply a convenience for the builder, because pipes that are too large are difficult to handle.

The stops making up a complete organ are a façade rank of sixteen or eight feet; if the organ has no 16’ stop, the 8’ open stop takes its place, the 16’ Bourdon and the Bombarde at unison, the longest pipes of these stops sound low C of the bass octave and are sixteen feet long.

The stops sounding eight feet or unison with the harpsichord, with their longest pipe eight feet long, are the stopped Bourdon of eight or four feet; as we have said, stopped pipes have only half [the pitch] of those which would be unison if open.

The 8’ open, the Trompette, the Cromorne, and the Voix Humaine.

The stop at the fifth of eight feet is the Gros Nazard.

Those sounding four feet, or an octave above the harpsichord, and the Prestant, which is used to lay the bearings for tuning the organ , the Flûte, the Clairon, and the Voix Angélique.

The stop sounding a third above the latter is called Double Tierce .

The stop a fifth above is the Nazard, which therefore sounds the octave above the Gros Nazard.

The stop sounding a fourth above is called the Quarte de Nazard ; its longest pipe measures two feet.

The Doublette sounds the unison of the latter, therefore two feet.

The Trompette de Récit has only the two treble octaves, sometimes two octaves and a fifth; it sounds eight feet. The Flûte Allemande has the same two octaves; consequently, it sounds in unison with the treble eight feet or four feet.

The Grand Cornet, the Cornet de Récit, and the Cornet d’Écho usually have only two octaves or two octaves and a fifth; they are composed of the trebles of the five following stops: Bourdon, Flûte, Nazard, Quarte de Nazard, Tierce.

The Fourniture and the Cymbale are composed like the Cornets, the difference being that although they have full keyboard compass, they only contain the treble octaves of the Cornet ranks, which repeat, as explained in the articles Cymbale and Fourniture.

The Tierce sounds an octave above the Double Tierce; it has four octaves.

The Larigot, the highest stop in the organ , sounds the octave above the Nazard, and the fifth of the Doublette or two feet.

The interval from the lowest pitch in the organ , low C in the bass Bourdon or the 32’ Montre, to the highest, high C of the Larigot, is eight octaves and a fifth, but notes as low as the 32’ octave are scarcely heard below F , so usually the lowest notes are eliminated, because their size causes substantial inconvenience. This runs counter to the prejudice of less-educated people, who imagine that the largest pipe in an organ is the one that makes the most noise.

In the list of stops that we have just presented, we have not noted which are the reed stops; this omission is amply repaired in the article Stops, in which their characteristics are explained, and in the separate articles devoted to them. Here let us say only that the stops are the Bombarde, the Trompette, the Cromorne, the Voix Humaine, the Voix Angélique, and the Trompette de Récit.

The stops called “pedal” because they are played with the feet on the pedal clavier are the Bombarde, pedal, a reed stop often of sixteen feet, which if it has a short octave goes down to 32’ F .

The Trompette, pedal, a reed, sounds in unison with the bass and tenor of the eight-foot Trumpet; if it has a short octave, it goes down to 16’ F .

The 8’ pedal, a mutation [flue] stop, speaks the unison of the latter.

The Clairon, pedal speaks the unison of the bass of the Clairon; its short octave goes down to eight feet.

The 4’ pedal or Flûte, pedal, a mutation [flue] stop, speaks the unison of the bass of the Flûte; its short octave, if it has one, goes down to eight feet.

The pedal range of the various stops only differs in having larger dimensions and lower pitch, if they have a short octave. See the corresponding articles.

Everything set forth above has explained the building of an organ .

We shall only add a brief recapitulation to explain the mechanism of the instrument, referring for the details to the separate articles throughout this Dictionary, first discussing the arrangement of the stops inside the organ case.

Each stop is aligned on its own slider or register, which as we have said is parallel to the front of the case, with the large pipes towards the ends, as explained in the article Rollerboard. Exceptions to this rule are the façade or display pipes, and those whose volume takes up too much space. In this case, wind is supplied to them by lead tubes, with one end at the foot of the pipe and the other in the hole on the windchest where the pipe should stand.

The organ can speak only when the bellows supply it with the air that is its soul, so it is necessary to have an assistant who raises the bellows by pulling down the levers in alternation. See Bellows. He must be careful not to raise two at a time, and after he has raised a bellows, he must let it down gently on the air it contains: as long as the board is raised, the air is not condensed and therefore unable to withstand the load of the top board; by releasing the bellows gradually, the air is condensed enough to support it. Moreover, the shock causes an unpleasant shaking in the pipes that are speaking, and the audience notices it. In addition, the bellows suffer considerable damage.

The organist sits at X [Plate I], on a bench of suitable height, with his feet resting on an iron rail, a b , [9] called the footrest ; first he draws the stops. Drawing the stops means opening the sliders by means of square rods SR located within his reach; they rotate vertical rollers PQ and swing lever Vu , which draws the slider, making its holes correspond to those in the windchest and the toeboard. See Drawstop. When he has drawn all the stops he wishes to use in the Pedal, Great Organ and the Positive, no stop speaks, although the bellows boards are raised and the pallet boxes of the windchests are filled with wind. Only when he depresses a key connected to a pallet in the pallet box by a roller on the roller board, opening the pallet, does the open pallet let the wind in the pallet box enter the corresponding channel; the wind will pass into the pipes whose sliders are open and make them speak. The same applies to all the keys, manual and pedal, and the keyboards for the Great Organ and the Positive. See the articles Keyboard, Rollerboard, Windchest, etc.

It will readily be seen that stops can be varied and combined, since one can open or close the ones one deems appropriate; but some of them must never be used alone, like the Fourniture and the Cymbale, and others must never be used together, for example the Quarte de Nazard and the Nazard, or the Nazard and the Larigot, because together they make a fourth. See on this point the article Stops, where there are examples of various possible combinations of stops.

As for how to tune an organ, see the articles Tempering and Tuning.

1. The term “bois de vauge” apparently means “Vosges lumber,” oak from the Vosges mountains (Translator’s note).

2. I use the English near-equivalents of the old pied, pouce , etc. (Translator’s note).

3. The French uses fût , suggesting both “trunk” and “base” (Translator’s note).

4. The plate gives “X” instead of “C” (Translator’s note).

5. The original gives “abc” (Translator’s note).

6. The Plate shows three parts (Translator’s note).

7. The figure does not have numbers 6 and 2 (Translator’s note).

8. In fact, the top of the foot (Translator’s note).

9. The original gives “o b” (Translator’s note).