Organ

The principle of the hydraulis, which long remained a mystery, is now well understood. An inverted funnel, or bell of metal, standing on short feet and immersed in water within the altar-like receptacle forming the base or pedestal, communicated, by means of a pipe, with the wind-chest, placed above it. When the air was pumped into the funnel by the alternate action of two pumps, one on each side of the organ, constructed bucket within bucket and fitted with valves, the water retreating before the compressed air, rose in the receptacle and by its weight held the air in a state of compression in the funnel, whence it travelled through the pipe into the wind-chest. For an interesting discussion of the hydraulic organ, based on a careful first-hand study of the ancient writers see two articles in The Organ for Jan. and April, 1923 by D. Bati gan Verne.

The nature of the hydraulis made it possible to construct large organs of powerful tone more suitable for use in the arena than the small pneumatic instruments, but the hydraulic organ never entirely supplanted the pneumatic, which was probably not so imperfect at the beginning of our era as has been thought, and which was destined to establish its supremacy in the end.

In France and Germany the Romans must have used organs and have introduced them to the conquered tribes as they did in Spain, but the art of making them was soon lost after Roman influence and civilization were withdrawn. Pepin, when he wished to introduce the Roman ritual into the churches of France, felt the need of an organ and applied to the Byzantine emperor, Constan tine Copronymus, to send him one, which arrived by special em bassy in 757 and was placed in the church of St. Corneille at Compiegne. The arrival of this organ was obviously considered a great event, since it is mentioned by all the chroniclers of the time. Charlemagne received a similar present from the emperor of the East in 812, of which a description has been preserved.

Considerable activity was displayed in England in the loth century in organ-building on a large scale for churches and monas teries, such as the monster organ for Bishop Aiphege at Win chester, which had 40o bronze pipes, 26 bellows and 2 manuals of 20 keys, each governing 10 pipes.

In regard to the details of these early instruments, as repre sented in contemporary illustrations, it may be noted that there is no miniature on record in which the fist action on the keys is indicated, the performer during the loth, Iith and 12th centuries being depicted in the act of drawing out the stop-like sliders--fas for instance, in the i 2th-century manuscript Bible of St. Etienne Harding at Dijon, where the organist is playing the notes D and F, the sliders being lettered from C to C. From the 13th century the

keys are shown pressed down by means of one finger or of finger and thumb. In the beautiful Spanish ms. said to have been compiled early in the 13th century, known as the Cantigas de Santa Maria, a portative is shown having balanced keys, one of which is being lightly pressed by the thumb, the instrument rest ing on the palm—while the left hand manipulates the bellows. The keys themselves varied in shape, being either like a T; a wide rectangle, with or without the corners rounded off, or a nar row rectangle. The earliest instance of a chromatic keyboard is that of the organ at Halberstadt built in 1361 and restored in 1495• (K. S.) THE MODERN ORGAN In former centuries organs were seldom to be found outside places of worship, hut at the present day they are built for use in private residences, concert and public halls, cinematograph theatres, and in many playhouses of the United States and Canada. The sounds of an organ are produced from pipes of varying shapes and sizes, made to "speak" by means of air under pressure.

The sounding of the pipes is determined by the use of the keys, some of which are played by the hands, some by the feet. The keys of the organ resemble those of the pianoforte in appearance; but whereas the pianoforte has only one keyboard or manual the organ may have four or five in addition to a keyboard of foot pedals.

Stops.

Each organ pipe sounds one note only and is a mem ber of a larger unit known as a stop; each stop is a member of a still larger unit known as a sectional or divisional organ ; while each sectional organ is a member of the grand organ in its totality. To the layman the term "stop" usually denotes the knobs grouped on each side of the organist as he sits at his console or control board. In watching the organist pull out or push in these knobs with varying musical results he does not think twice about accepting the term "stop," as popularly understood. To the organ builder, however, it means one thing and one thing only, namely, a rank of pipes.

The pipes of a given stop therefore all produce sounds of similar quality, but necessarily of different pitches. No two stops are exactly similar in quality ; on the contrary, they all differ, like the various instruments in an orchestra. Some stops are of high pitch, some of low; some have a thin, some a full quality of tone. The knob at the console is the only part of the stop mechanism that is visible, being merely a handle which actuates the valve admit ting wind to the stop itself. Every stop has a separate knob, just as every note has a separate key. Unless one of the knobs were drawn no sound would result when the organ was played.