Rockstro, in his massive compendium "A Treatise on the Flute", London 1890, sets us an intriguing puzzle - an alleged change in bore used in Rudall & Rose's conical flutes. But there are no real details - can we deduce more? Here's Rockstro's entry on the topic:
665. Improved Conoidal Bore by Rudall, Rose and Carte. In the year 1851, or perhaps rather earlier, Messrs. Rudall, Rose and Carte wisely ceased to make conoidal flutes after Boehm's model, and they brought out a new bore which greatly improved the tone, though its proportions only differed slightly; in actual measurement, from the fine one that had so materially assisted the fortunes of the firm.
[By which we assume he means the bore used on the ordinary 8-key flutes which were Rudall & Rose's bread and butter up till that time. This is a little odd, in that we can detect several, or perhaps even a range of bores in extant Rudall & Rose 8-key flutes, but perhaps Rockstro, coming much later wasn't to know this. We can be confident that "the fine one" was nothing to do with Boehm!]
The lines of the new bore were straight, there being no longer any necessity for resorting to "chambering :" see §340. The following interesting remarks on the bore of the flute are extracted from the pamphlet of Mr. Carte (1851, p.21).
666. "It appears that Boehm's investigations, which led to his discovery of the parabolic head and cylindrical tube, arose from the circumstance that he could not obtain a tone so fine in the lowest notes of the old conical body, used in his first flute, as in the rest of the notes. . . . . Now, it is to be observed that Boehm's having failed to obtain the notes in question so perfectly with the conical bore as he afterwards did with the parabola and cylinder, is no proof that these notes were not to be obtained with the old shape. On the contrary, there are reasons to be given why he might be expected to fail in this respect. One reason is this: the Germans, although the original inventors of the ordinary flute, have ever been slow in experimenting with the bore. Experiments in this direction have been chiefly made in England. In France very little was done in this way before the introduction of Boehm's flute. The eminent performers also, both German and French, have always aimed rather at mere sweetness of tone than power. Very different has been the case in England. No performers have ever approached the English in the union of a rich and large volume with sweetness of tone, and it has, doubtless, been from the desire to obtain this, that so many experiments have been made by the English performers and manufacturers with different-sized holes and variations of the general bore.
667. "Tacet . . . . in the last century, experimented with large holes, as did also the late Mr. Nicholson's father; but the most important improvements as to the tone of the ordinary flute, especially those gained by variations in the bore, have been effected by Messrs. Rudall and Rose. Now it may easily be conceived that Boehm, who is a German, coming necessarily, as he did, to the subject without much previous experience with regard to the bore, and falling upon, or turning his attention to, the more scientific mode of shaping the tube before he had exhausted the resources of the conical tube, did not ascertain to the fullest extent the capabilities of the old shape. I am also convinced that this was the case by experiments which have lately been made. As it was thought that flutes of wood, of the parabolic and cylindrical shape, if made sufficiently thin to be held comfortably in the hands, would be liable to crack, and as some preferred the tone of the wooden flute, while others could manage the embouchure of it better than that of the same flute in metal, strenuous efforts have been made by Mr. Rose so to vary the proportions of the cone as to correct the defective notes mentioned as having existed in the first of Boehm's flutes; and so successful have been his efforts, that not only are these notes rendered equal to the others, but so much is the general tone of the instrument improved, that it becomes a matter of opinion whether the wooden flute with parabola and cylinder, or that with this improved conical bore, is now the better."
But there are some clues. It's clear that we are talking post 1847 when Boehm released the new cylindrical bore.
Before pressing on, let's remind ourselves of the environment that enveloped the London flute world in the second quarter of the 19th century. Nicholson had introduced large holes to the classical 8-key flute around 1816, creating an "Improved" flute that was much louder but that had some pretty spectacular tuning issues. Rudall and Rose started making such flutes in 1821 and soon became the pre-eminent company. Under their manufacture, slow change gradually ameliorated the tuning problems, although not to the extend we can now show is possible.
In 1831, Boehm visited London and was astonished at the power Nicholson could achieve in his performances on the Improved flute. Boehm realised that he could only achieve similar performance by redesigning his own flute.
Back in Munich in 1832, Boehm came up with his new design, a conical bored flute with holes placed where they should be, and a keying system to make those holes accessible. Although probably the first flute anywhere to play in good tune, it didn't set the world on fire. The English found it underpowered and too complicated, and were unwilling to learn the new fingering system.
The French were more attracted to it, as power was not as important to them as sweetness, and a flute that is in tune is definitely sweeter than one that isn't. The new design received some working-over in France that made it a more competent instrument in general.
In 1843, Rudall & Rose, probably concerned that sales of 8-key flutes were starting to taper off, decided to take up manufacture of the 1832 ring key conical, but not in the original form. They needed to make some changes - for example to include a tuning slide to deal with the tuning chaos that still prevailed in England - and they opted to make others - for example retaining the preferred English elliptical embouchure.
It seems that, even thus Anglicised, the flute was still not destined to make great headway in England, despite heavy support from some leading music professors, among them Clinton and Carte. And things were hotting up elsewhere. Cornelius Ward and Abel Siccama brought out new models of flutes which also offered improved intonation, and in Siccama's case, substantially greater power. Boehm re-enters the fray in 1847 with his new cylindrical bore, offering buckets of power but a very different sound. And finally, Clinton, thoroughly disappointed in the direction Boehm has taken, decides to take matters into his own hands, with a patent in 1848 and a flute ready for the 1851 Great Exhibition.
So there's the context, and it's not surprising if Rose was burning the midnight oil looking for a new bore. Something surely had to be done if boats were not to be missed!
The chart below tells us a lot about what was happening, but may require a bit of explanation. To give us a basis of comparison, let's start with the kind of bore Rudall & Rose were using on their 8-key flutes. The brown trace running down the middle of graph is from Rudall & Rose No 5384, chosen as it falls into the approximate time-scale in question. It's a typical medium-large holed flute of the time, offering very good power and, by that time, reasonably good intonation (for an 8-key).
Boehm's own flute (the yellow trace) has a substantially narrower bore, and can be expected then to give a less full-bodied sound. The better venting probably gave good performance in the middle and upper regions, but, as Carte puts it, Boehm "... could not obtain a tone so fine in the lowest notes of the old conical body, used in his first flute, as in the rest of the notes". As the graph illustrates, Rudall & Rose used virtually the same bore in their copy of Boehm's flute (the green trace). And the same bore can be seen again in France late in the 19th century (the pink trace).
Rudall & Rose also used the Boehm bore in early versions of Carte's 1851 patent flute (the light blue trace), a matter we'll return to later.
Now while that bore might satisfy the lesser demands of the French and Germans, it would completely disappoint an English player. Pay all that money and learn a new system and not be able to get the big bottom notes you could on the old Improved-period 8-key. I don't think so!
It shouldn't take you long now to spot the Improved Conoidal Bore, in lurid orange on the graph above. Not only substantially larger than Boehm's bore, but also substantially larger than the old 8-key bore. This one used on Rudall, Rose and Carte's 1851-patent, No 45.
Now a new bore doesn't just pop out of nowhere - it takes heaps of work to perfect. A change anywhere in the bore can make changes everywhere in terms of intonation, quality of note and power. Hard work!
Usually you can find a precedent that probably was the inspiration if indeed not the model for the bore. And I think we can in this case. Check out the bore of Siccama's flute, in purple, in the graph above. Note that particularly in the foot region (and we were worried about low notes, remember), the bores are very similar. And certainly Siccama had somehow come up with a bore that gave better intonation and much more power than even a contemporary Rudall & Rose 8-key. It certainly trounced Boehm's flute for power, and was starting to attract a lot of attention in the market. And we know that Rudall & Rose were aware of it - Carte and they had gone to see Siccama at his invitation to view the new instrument, and Carte had borrowed it for a while.
So if Siccama had a flute in good tune and with oodles of power, why not snitch his bore? We have to remember that Siccama's flute was essentially an 8-key design, with two extra keys to permit the four remaining open holes to be much better located than is possible on an 8-key. It still had the other closed keys, and so enjoyed far less venting in the middle and upper end of the tube than Boehm's all-open system achieved. So Siccama's bore would have been too narrow at the top for Boehm's key system, and would have produced excessively wide octaves. Indeed, you can see that it drifts back to join the Rudall Rose 8-key bore for the upper third where the cumulative effect of reduced venting applies most.
Now whether Rose would have known this instinctively we cannot say, so it's probably more realistic to imagine that he might have made a flute with Siccama's bore but Boehm's hole pattern and then found out. But it wouldn't be hard then to continue scooping out the upper part of the tube until that over-correction was brought under control.
Now this is of course surmise - it is possible that Rose worked entirely from scratch, but the history, timing and the end results lend support to our theory.
The first thing we can say with seeming 100% surety is that the new conoidal bore was not used on 8-key flutes. Rudall 8-key flutes during and well after this period stuck pretty close to the 8-key bore shown above. Indeed, the new bore would run into venting problems at the top end of an 8-key.
So where do we look to see evidence of the new bore? Clearly, it has to be a well-vented instrument, like the Boehm, or Carte's 1851 design.
Ah, interesting question! If Carte's old mate Rockstro could only venture "In the year 1851, or perhaps rather earlier" in 1890, what can we expect to do 150 years after the action? Examine the forensic evidence is what. Hmmm, there's not much of it ....
2 Patent granted (usually within 6 months of lodgement) presumably 1851, for the flute to have picked up the popular descriptor
4 Ditto, RR 33 made, with seeming new or intermediate bore (13.5mm at end of body) must be between 3 & 5
7 RR&Co publishes Carte's "Sketch of the Successive Improvements" which mentions the new bore after 6
8 The Great Exhibition opens, presumably incorporating Carte's 1851 Patent flute at that time 1 May 1851
So, on the current evidence, it seems the new bore came in during the first few months of 1851 and around flute number RR 33 or 34. If you have evidence to add to our list, please let us know and we'll plug it in and make the necessary adjustments.
So was it a clean jump from old to new, was there an intermediate step or indeed did they run with both as options for a while? The 13.5mm end diameter of RR 33 seems to suggest there might be an intermediate step, but we await more information to clarify this. And we're really need more extant flutes to be able to answer the other question.
Now, having seemingly put all this effort into developing a new bore, why not patent it? It seems odd that, looking at all the patents lodged over the years, only one of them relates to that most fundamental of flute determinants, the bore. Keying-systems, construction methods, materials all get a look in, but the only patent relating to bores seems to be Rose's safeguarding of Boehm's cylinder bore. Perhaps they thought the concept of a bore was patentable, and patent-worthy, but not the actual dimensions. So Rose's new conoidal bore, Siccama's bore, indeed anyone's bore were all available for universal use.
And it seems conversely, that everyone felt perfectly happy for anyone to make use of such developments. There are plenty of acrimonious discussions recorded in the musical press, but none of them relate to snitching the dimensions of the hole up the middle.
Indeed, note something else. The only "new conoidal bore" flutes we have current evidence of amounts to maybe 4. And at the moment, that's it. Museums and private collections are not exactly brimming with them. Indeed, note above that No 34 had to be pre May 51, and No 45 had to be after the next change of name and the move to New Bond St in 1852. There are a few more conical Boehm ring-keys about, but so far all the ones I've seen are Rudall & Rose, employing the old bore. Supposing you created a bore and nobody proved interested!
Well, according to Carte, Rose put the work in. And as Carte noted: "that it becomes a matter of opinion whether the wooden flute with parabola and cylinder, or that with this improved conical bore, is now the better." Whose opinion? Probably not Carte's, as he invested all his enthusiasm on more familiar fingering systems to apply to Boehm's new cylinder bore. Well, Rose's opinion, of course, or he wouldn't have bothered. But perhaps Rudall as well. Here are men who's flute-making lives had covered the greatest days of the cone flute, from Monzani and Nicholson, through Boehm's conical and Siccama's 10-key, right up to the introduction of the cylinder. One can imagine both of them embracing the bold new cylindrical future with gritted embouchure. Certainly Rudall left the company within a few years - it doesn't seem clear how much longer Rose remained involved.
For many years, Rudall played on an eight-keyed box-wood flute, with what were then considered large holes; at the age of sixty-two he successfully adopted the so-called Boehm flute, with the open G# key, and four years later he made a further change to the "cylinder flute". His nephew, Mr. Frank Rudall, informs me that the old gentleman "always felt a lingering fondness for the box-wood eight-keyed instrument on which his early triumphs in the musical world had been achieved." One can scarcely wonder at this, considering his advanced age when he changed his fingering.
So did no-one benefit from the new conoidal bore? Fortunately yes, but not someone Rose might have predicted, or anyone else seems to have noticed. Look at the dark blue curve hugging the lurid orange. Rose's new conoidal bore (or something remarkably like it) was to be the basis of Clinton's range of multi-key flutes, starting with his 1851 model (made by Potter and exhibited along with Boehm and Carte's flutes in the Great Exhibition), and going on to his range of Equisonants.
Perhaps the only fly in that ointment is the timing. If we're right that the Rose's New Conoidal Bore was introduced in early 1851, it didn't leave Clinton much time to adopt it by the May 1 start to the Great Exhibition. We'll have more to say about that in our Clinton articles. But it would be nice to think that the new bore had a future, even if it had to be propping up the fortunes of a competitor.
Really, at this point there can be no conclusions - we are still rather light-on for evidence. Better to treat the above as a speculation that seems to fit the evidence we can so far muster. I'll certainly be glad to hear of any other information that might support or modify the current theory.