ORGAN, CONSTRUCTION OF. We have on record several kinds f hydraulic, the Pneumatic, the Barrel, and the Finger or 'hunch organ.
Of the hydraulic organ we know little beyond its having been perated on in some way by water : it may have resembled the clepsydra, r water-clock, which chimed at certain hours ; but as the passage of eater through the pipes would nut produce musical sounds, it is pro able that water was employed as a moving power. Indeed, the plan f using water-power to work the bellows of an organ or harmonium As lately been revived, and the water engine may now be considered s an essential feature of an instrument which requires so large a apply of wind. The pneumatic organ, whether more or less ancient han the hydraulic, was certainly the parent of the present finger-organ ; int it was so decidedly rude in its construction, that it must always be onsidered as a distinct instrument. 'I'ho barrel-organ is a machine with little variety and no expression ; it nevertheless contains many lever contrivances, and is daily receiving improvements. The present inger-organ is the largest and noblest of all musical instruments ; its 'ewer is that of a full band, and for delicacy and sweetness of tone it s unrivalled.
In such an organ there are several thousand pipes, with arrangements or enabling the organist to make any single pipe of the number speak without disturbing any of the others. Now to do this there must be, I, a bellows for eupplyiug condensed air or wind ; 2, a channel for :onveying it to the pipe in question ; 3, a valve, or some contrivance or admitting wind to this pipe when it is required to speak, and for :utting off the supply when it is required to be silent ; 4, a lever for )pening or shutting this valve. There are many other contrivances for producing variety of effect, loudness or *softness, qualities of tone resembling various musical instruments, dee.
The sets of dipee in an organ are called stops ; the corresponding notes of the different stops may agree in pitch, that is, they may be in unison; or they may produce a chord or an octave above. They differ however in quality of tone. Each atop is, in fact, a range of pipes of the same quality of tone, and extending throughout the com pass of the instrument. When a certain stop is drawn, the keys will play throughout on pipes of that character of which the stop consists.
A complete and full finger organ should have three sets of keys, and at least two octaves of pedals.
The first set of keys takes the swell, the second the great organ, and the third the choii.. The compass, as well as the size of organs, must depend upon circumstances. The German scale or compass is cc to in alt ; the English formerly descended to o below, but are now generally constructed on the German principle ; the pedal organ taking the notes down to c c c, which, for duet and solo performances, is cer tainly the best. A good swell is always important to an organ, and we should recommend cc to F in alt as the compass to be preferred. The compa.s of the choir is generally the same as that of the great organ. These several parts, or organs, when brought together by stops, called couplers, give to the keys of the great organ the command of every pipe in the instrument, the power and majesty of which are without parallel in instrumental combinations.
Fig. 1 is a section of a large organ, showing the several situations of certain principal parts of the instrument, which, however, are variously placed by ditlerent organ-builders. A is the which is usually made of deal, and the thicker the better, but it certainly should not be less than an inch and a half iu thickness ; it must be lined with paper or leather to deaden the tone when shut. The front is formed of Lourre-boards, all of which are made to move on centres; they must also be an inch and a half thick. The performer opens them by a pedal expressly employed for opening and shutting the swell. This kind of front is what is known by the name Venetian. n is the choir or part in which the pipes of that part of the organ are placed ; o is the great organ which also contains its pipes ; n is the s Is the pedal ; F ie one of the front pipes, to which the wind is conveyed by metal tubes, called conveyances; o o o are three roller boards, one for each organ ; is is a tracker, used with squares and centres to reach distant parts of the action ; at a arc the Leys ; at x are the pedals ; L is the seat. The numerous things which are nut indicated in this figure must be sought for in teorkin5 drawings, as we cannot and do not pretend to give these matters a practical form.