ORGAN - CONSTRUCTION.
Srn—The observations in your paper of 17th December under the bead of "Sydenham Palace Organ," appear to invite the support of musical experi- mentalists.
Before determining on outdoing all past performances by the fabrication of an organ with pipes of 60 feet in length, ought not care to be taken to be
certain, that a sound deeper than that of the present 32-feet pipe is possible in rerum natuni P If it is not, would not the promoters of such an attempt be found in the same predicament, as a hydraulic engineer who should have endeavoured to raise water through a tube of 60 feet long in the manner of a pump, in ignorance of the existence of a principle by which water cannot be so raised to a height exceeding thirty and odd feet ? You refer to the announcement of Chladni. It may be Chladni's in another shape, but a more striking form of the experiment is Savart's. He determined, that no continuous sound can be produced by fewer than sixteen vibrations in a second, any smaller number being heard as so many distinct noises. If it may be inferred from this that fewer than sixteen vibrations in a second cannot constitute a musical sound, it follows that if Euler and Dr. Smith were correct in stating concert A to be made in their time by 392 vibrations in a second, the pitch of concert A must have been raised by more than half a tone, to bring such a note as CCCC (which is what the organ- builders at present express by means of a 32-feet pipe) within the limit of possibility. What is to be looked for therefore is, that the consequence of fabricating a pipe of greater length than what by calculation should give sixteen vibrations in a second, will be that the pipe, in the phrase of organ- builders, " will not speak its note," but will break into the octave or some other of the harmonic sounds. In confirmation of which, a musical friend at Dublin has stated, that he is acquainted with a chimney a hundred feet high, and from six and a half to seven feet in diameter, which under certain circumstances of the wind exerts itself so vigorously as an organ-pipe, as to have been threatened with indictment as a nuisance, people from seventeen miles off being brought to depose to the noise ; and he thinks the note is FRE fiat, whiCh is an octave and a minor third above the sound of CCCC, where- as according to the proportion of the lengths, it ought to be between one and two octaves below it.
It certainly does not follow without further inquiry, that either Chladni's or Savart's experiments are conclusive on the point in question. But there is a dangerous probability about it, which makes it more politic to institute the inquiry before failure than after. Which shall be returned to, after some remarks on a connected subject. The writer of this May_bc all wrong, and he cannot profess to have had the opportunity of carrying experiments to the desirable extent. But from what he has seen he feels a strong conviction, *ea organists and musi- cians in general have no idea ol the enormous to which pipes of great dimensions are affected by variations in the ture, and the utter ab-
sence, at least under present forms, of any of counteraction. There is
ao organ in which the metal GG of Open Diapason of six feet long, (which is a said ,within the compass of bass voices,) even though the precaution is takend tuning at a medium -temperature, wilt not sound AA flat in sum- mer and FF 'sharp in ',auger, -when compared with the high gg in the tre- ble, the alterations of which are comparaliVely trifling. Imagine a base singer or violoncello-player sounding A fiat or F sharp to the g of the treble. And for this, under existing systems at least, there is no remedy ; for to at- tempt to keep in pipes in tune by continual re-tuning, would, if practi- cable at all, be n two seasons destructive to the pipes. But it' this is the case with the pipe of six feet, what is it to be with pipes of 16 and 32, if it be true (as experiments on a small scale appear to inti- mate) that the effect of atmospheric changes varies as something more than the square of the length of the pipe? It seems hardly compatible with pos- sibility that this rate of variation ahouldbe extended to the largest pipes; but it amounts to proof that the effects on them must be enormous. Has any effort been made to obviate these conaequencee % Not the smallest. A builder cuts a pipe to the length of 82 feet, at— says " Stand there and be CCCC " ; without taking note of the fact, that very ordinary variations of the thermometer will cause the pipe to sound almost any other of the sounds in the octave. Under such circumstances, even if the absolute impossibility of the supposed attempt were disproved, it would be wiser to endeavour to construct pipes that shall maintain some certain sound, than to increase the perplexity for the sake of astonishing such of the natives as measure their music by the rood. The way to proceed to remedy, would, if no unforeseen objection exists, be to place the large pipes horizontally, and furnish each of them with what may be termed a cap, or portion of tube to lengthen and shorten after the man- ner of a spy-glue. Not to leave this to be conceived of as something vision- ary or microscopic, in the 32-feet pipe its length would probably require to approach to a fourth of the whole. If, as suspected, it is not essential to a continuation of this nature that it should touch, the cap might be made an inch or two larger in diameter than the rest of the pipe, and by easy contri- vances be laid so as to be moved backwards or forwards without difficulty. By marking the places in two extreme and one intermediate temperature, a scale might be made upon each of a suit of large pipes, by means of which they might with the greatest ease be altered pro or nalgi. After which the ready way to try the question of whether there is a zero of deep sounds, would be by seeing whether there is a limit to what cau be coaxed out of a 32-feet pipe by extending the cap. The organ-builders appear to have a notion that it is of no consequence whether these large pipes are in tune or not. If it is really of no consequence, an inference very unfavourable to the utility of such pipes at all, would ap- pear to be the result. But there must be some mistake. It probably arises from the diminished facility of tuning the large ppippeese ; which is the con- sequence of the slowness of the vibrations. A difference in pitch which among the higher sounds will make a difference of ten or twenty beats in a second, in one of these large pipes will only make one, or, it may be, the fraction of a beat. The way to obviate this, is to tune by means of a wire loaded with a variable weight. If the wire is loaded to the pitch desired, and the weights noted, and then loaded to the points where it ceases to be sensibly too sharp and too fiat for the pipe, and the mean of these weights taken, the difference between this mean and the weight first noted will show which way the pipe is wrong ; and it may be altered accordingly. For applica- tion to pipes approaching to CCCC, such a wire should be a tenth of an inch in diameter, eight feet long, and loaded with 250 pounds, more or less, ap- plied by the intervention of a lever in the manner of a steelyard, which shall quadruple the effect on the wire. I cannot help thinking that in some parts of this there are evidences, that something is more urgently wanted than astonishing the eyes of the ground.. Hugs by pipes of sixty feet long, which after all may turn out only " make- believes.' If there is an anxiety to be sued for a nuisance by persons seven- teen miles off, the way to do it appears to be by making pipes with what the organ-builders call " an increased weight of wind." An organ-builder takes a glass tube with two bends, like a compressed S. In one of the bends he puts a few inches of water, and then inserting one end of the tube in the place of a pipe of the organ, he sees whether the pressure of the air from the bellows raises the difference of level of the water on the two sides to one two, &c. inches, and says his instrument has one, two, &c. " inches of wind accordingly. Two inches are considered an ordinary weight, and three rather large; but I have understood that at York Minster there is a stop called Tuba .1firabilis, in which the "weight of wind" has been stated at fourteen inches. If the object at Sydenham is the one that has been men- tioned, this is the track which ought to be followed. A brass band is available in the open air ; and the largest glass house cannot be larger. There is probably no comparison between the strength of sound of any single brass instrument and the Tuba Mirabilis ; and therefore the projectors have in this way the game in their hands. Half a dozen stops of the Tuba Mi- raln7is would make a noise which no human ear would willingly encounter a second time.
Remains the question after all, whether the national glory is implicated in making the loudest noise that has been heard since Tubal was father of such as handle the harp and organ. If it will pay, it is impossible to blame the projectors. But there will probably always be a remnant who will refuse to call it music. At all events, before money is spent on 60-feet pipes, let it be known whether Nature has not set up her canon against the expected
Previous page
