ORGAN
299
ORGAN
had been all of our open diapason kind, which in
principle is the same as the toy-whistle. These were
now made in different "scales" (scale being the ratio
of diameter to length). Also, the form of a cone,
upright or inverted, replaced the cyUiidrical form.
Stopped pipes — that is, pipes closed at the top — were
added, and reeds — pipes with a "beating" reed and a
body Uke tlie "flue" pipes — were introduced. Thus,
by the sixteenth ceatury all the main types now used
had been invented.
The keys in the early medieval organs were not, it seems, levers, as in the ancient organ and modern in- struments, but simply the projecting ends of the slides, being, presumably, furnished with some simple device making it convenient for the fingers to push in or pull out the slides. The invention of key-levers is gener- ally placed in the twelfth century. These were for a long time placed exactly opposite their sliders. When, tlierefore, larger pipes began to be placed on the sound- board, the distances between the centres of the keys had to be widened. Thus we are told that organs had keys from three to five inches wide. This incon- venience was overcome by the invention of the roller- board, which is placed in the fourteenth century. The rollers are rods placed longitudinally under the sound- board and pivoted. From each two short arms pro- ject horizontally, one being placed over a key, the other under the corresponding shder or valve. Thus the length of the key-board became independent of the length of the sound-board. Consequently we learn that in the fifteenth century the keys were so reduced in size that a hand could span the interval of a fifth, and in the beginning of the sixteenth the key- board had about the size it has at present.
The number of keys in the early organs was small : only about one or two octaves of natural keys with at most the addition of b flat. Slowly the number of keys was increased, and in the fourteenth century we hear of key-boards having thirty-one keys. In the same century chromatic notes other than 6 flat began to be added. Then the question of tuning be- came troublesome. Various systems were devised, and it was not till the eighteenth century, through the powerful influence of J. S. Bach, that equal tempera- ment was adopted. This consists in tuning in fifths and octaves, making each fifth slightly flat so that the 12th fifth will give a perfect octave. About the be- ginning of the sixteenth century the lower limit of the key-boards began to be fixed on the Contipent at C, the c that lies below the lowest tone of the average bass voice and requires an open pipe of about 8 feet in length. In England organ key-boards were gen- erally carried down to the G or F below that C, and only about the middle of the nineteenth century the continental usage prevailed also here. The total compass of the manuals now varies from four and a half to five octaves, that of the pedals from two oc- taves and three notes to two octaves and six notes (C — d' of C^'). In 1712 it occurred to a London organ-builder named Jordan to place one manual de- partment of the organ in a box fitted with shutters which could be opened or closed by a foot-worked lever, a kind of crescendo and decrescendo being thus obtained. This device, which received the name of swell, soon became popular in England, while in Germany it found favour only quite recently.
As we have seen, all through the Middle Ages the blowing apparatus consisted of bellows which deliv- ered the wind directly to the sound-board. It was only in the eighteenth century that two sets of bellows were employed, one to supply the wind, the other to store it and keep it at even pressure. Thus, after an interval of about a thousand years, the blowing appar- atus regained the perfection it had possessed in the hydraulus during the preceding thousand years. In. 1762 a clock-maker named Cummings invented a square, weighted bellows, serving as a reservoir, and
supplied by other bellows called "feeders". The
feeders are generally worked by levers operated either
by hand or foot. In quite recent times machinery has
been applied to supersede the human blower, hydrau-
lic, or gas, or oil engines, or electromotors being used.
The difficulty of regulating the supply is easily over-
come in the case of hydraulic engines, which can be
made to go slowly or fast as required. But it is serious
in the case of the other engines. Gas and oil engines
must always go at the same speed, and even with elec-
tromotors a control of their speed is awkward. Hence,
nowadays. IkHows serving as feeders are frequently
supersc.le.l liy <i'iitrifugal fans, which can go at their
full speetl witliout delivering wind. It is sufficient,
therefore, to fit an automatic valve to the reservoir,
which will close when the reservoir is full. There is
this drawback in the fans: that to produce a pressure
as required in modern organs, they must go at a high
speed which is apt to produce a disturbing noise.
To obviate this difficulty several fans are arranged in
series, the first raising the wind only to a slight pi'es-
sure and so delivering it to a second fan, which de-
livers it at an increased pressure to the next, and so on,
until the requisite pressure is attained by a practically
noiseless process.
A genuine revolution in the building of organs was brought about by the invention of the pneumatic lever. Up to the twelfth century, it appears, the "touch" (or key-resistance) was fight, so that the or- gans could be played with the fingers (see an article by Schubiger in "Monatshefte flir Musikgeschichte", I, No. 9). Later on, possibly with the change to the groove and pallet system, it became heavy, so that the keys had to be pushed down by the fists. With im- provement in the mechanism a lighter touch was se- cured again, so that playing with the fingers became possible after the fifteenth century. Still, a difficulty was always felt. In large organs the valve which ad- mits the wind to the key channels (the pallet) must be of considerable size, if all the pipes are to get sufficient wind. Consequently, the wind-pressure which has to be overcome in opening the valve becomes so great that it taxes the power of the organist's fingers unduly. This difficulty is increased when couplers are used, as the finger then has to open two or more valves at the same time. To overcome this difficulty. Barker, an Englishman, in 1832, thought of using the power of the wind itself as an intermediate agent, and he induced the French organ-builder Cavaille-CoU to adopt his idea in an organ erected in 1841. The device consists in this: that the key, by opening a small valve, ad- mits the wind into a bellows which acts as motor and pulls down the pallet. Once this appliance was thor- oughly appreciated, the way was opened to dispense altogether with the mechanism that connects the key with the pallet (or the draw-stop knob with the slider), and to put in its stead tubular-pneumatic or electro- pneumatic action. In the former the key opens a very small valve which admits the wind into a tube of small diameter; the wind, travelling through the tube in the form of a compression wave, opens, at the far end, an- other small valve controlling the motor bellows that opens the pallet. In the electro-pneumatic action the key makes an electric contact, causing the electric cur- rent to energize, at the organ end, an electro-magnet which, by its armature, causes a flow of wind and thus operates on a pneumatic lever.
With these inventions all the restrictions in organ- building, as to number of .stops, pressure of wind, dis- tances etc., were removed. Also means of control could easily be multiplied. Couplers were increased in number, and besides those connecting a key of one manual with the corresponding key of another, octave and sub-octave coujilers were added, both on the same manual and between different manuals. In the matter of a stop-control, combination pedals — that is foot- worked levers drawing a whole set of stops at a time —
