We will conclude this explanation of the pipes by stating that they are often 32 feet long in large organs, and so numerous that at Weingarten, in Germany, they number no less than 6,666; and in that organ are no less than 63 stops. At Haarlem also is one containing 60 stops.. The flute-stop in the Temple church in London is very sweet; and any of our friends that get the chance should hear that organ, as they will, if fond of music, find there a great treat.
We must now tell you about two additions to the mechanism of an organ - the swell and tremb The first is usual in good organs, but the latter is not so often used in this country. The swell consists of a number of open pipes placed in a box in the organ. This box has a moveable cover, connected with a pedal in front. By putting the foot on this pedal the cover is slowly raised, by which means the tone comes forth gradually, swelling louder and louder till the box is quite open; and by slowly letting the pedal go, the tones sink and grow softer and softer, till they die away by degrees. The effect is beautiful, if the player has good taste, and introduces The swell with judgment, which however is often not the case. The tremblant is a valve situated over the entrance of the bellows,- by which the air is allowed to enter by fits, giving a trembling mournful sound to the notes. There is a tremblant in the organ at the German chapel at the Savoy.
There are two or three other contrivances that we must explain, as they are of great use, the first of which is the tell-tale, by which the organist can see how much wind there is in the organ. To the top board of the bellows a cord is attached, which passes over a pulley, as in fig. 11. A is a section of the bellows; B, the pulley; C, a graduated piece of board, placed in front of the organ, and in light of the player: D, a piece of lead attached to the cord. It will thus be seen that when the upper board of the bellows is at its height, the Lead will have sunk on the board to a mark made on it, showing the bellows to be full of wind; hut as this wind is expended, the upper board sinks and the lead rises. At E is a safety-valve, to prevent the bellows from bursting. It opens inwards as soon as the board is raised so high that a peg or piece of wire attached to it comes into contact with a stop placed over it. There is usually a tell-tale in front of the organ, and one by the bellows-blower.
Such is the organ in its simplest form, as constructed for churches, and sometimes also for private houses; but of late years the grinding, or barrel organ, has come into use to a great extent, being constructed for the use of those who are not acquainted With music, or are incompetent to play upon those made with keys. When intended only for street-playing there is but one set of pipes; but when made for churches there are stops as in the finger organs. In each case the bellows are Worked by a crank upon the axis on which the playing-handle is fixed, and the valves are opened by levers communicating with a series of pegs on a barrel turned by the same handle. Fig. 12 is a section of such a
Barrel, with the pegs and levers. The different notes and tunes depend on the position of the pins in the barrel, each pin, as is evident, acting on the particular lever under which it revolves. The duration of each note depends on the length of each pin, for the long ones, as a, necessarily keep the valve open longer than such as b. Several tunes are arranged on one barrel, the barrel being shifted lengthwise at each, and retained in the same position by a catch acting on notches cut in one end of the axis. It is usual, also, when a great number of tunes are desired, to have several different barrels fitted to the same organ, either of which may be used at pleasure.
There is a great advantage in barrel organs, inasmuch as any one can play them, the only thing necessary being to turn the handle at the same rate; and for this reason they are often used in churches where music would otherwise have been impracticable on account of the difficulty of finding a person able to play upon a finger organ, At the same time, it is impossible to play the various tunes with as great effect as on the latter, which is certainly a drawback, when it is considered how much effect adds to the grandeur of any piece of music executed.