ORGAN

(Gr. opyavov, an instrument.) In Music, a Ai.nd instrument; so called by way of eminence, being indeed perhaps le an instrument than a machine containing a collection of instruments, or, in other words, a mechanical orchestra, under the command of a single performer's fingers on the keyboard. This instrument was invented at an early period, though until the eighth century it was probablv but little used. The Greeks appear to have been acoMnted with it; and, in the tenth book of his Architecture, Vitruvius describes an hydraulic organ which was played, or rather blown, by the fall of water, but in what precise manner is not now known. The emperor Julian eulogises rumen! in an epigram; and St. Jerome speaks of one, with twelve pair of bellows, which might be heard at tio: distance of n you sand paces; and of another, at Jerusalem, which might 1m; heard at the Mount of Olives. Its invention is attributed to Clesibius, a barber of Alexandria. The size of an organ is usually expre ed by the length of its largest pipes; thus an organ of 32 feet, of 16 feet. &.c, is one whose, lowest ba pipes are of those respective lengths. Church organs consist of two parts; viz. the great organ, which comprises the main body; nnd the chair, or choir organ, a smaller one, commonly placed before the other. The organ is provided with at least one set of keys; and when it has a chair organ and a swell organ, with two, three, or even more. Besides these there are pedals fur the lowest pipes, and composition pedals, which change the stops as required at one pre ure; both of these are acted upon by the feet. There is another pedal to open the swell organ with the right foot. The key boards of organs vary In extent: the York has 6 octaves from C C C (16 feet) to O in alt; the Birmingham 5J octaves; but the compa now in general use, here and on the Continent, is from C C (8 feet) to F in alt, 4£ octaves; the lower notes from C C to C C C (16 feet) being placed on the pedal organ. The G G compa is gradually falling into disuse, a compa which never prevailed on the Continent. Each key, being pre ed down with the finger, opens a valve or plug, corresponding lengthwise with as many holes as there are rows of pipes on the sound board; and the holes of each row are opened and shut by a register or ruler pierced with holes equal in number to the keys. By drawing the register the noles of one row are opened, because they correspond with those of the sound board; so that, by opening a valve, the wind brought to the sound board by means of bellows finds its pa age into the pipes which correspond to the open holes of the sound board. By pushing the register or stop, the holes therein not answering to any of those of the sound board, the row of pipes answering to the register so pushed is shut It in obvious, therefore, by drawing several of these [s. 875]