So we've looked at a number of flutes from a number of perspectives, what conclusions can we draw?
Early English 8-key, exemplified by Richard Potter (post 1785)
A narrow bore, with long scaling and poor, but fairly uniform venting. We'd expect a quiet instrument, best at low pitch, with a reedy tone if pushed, not that you would. And that's exactly what we get.
Nicholson's Improved (post 1816) and the flutes based on it
Nicholson's dad opened up some of the holes on his old Astor and sent young Nicholson off to London with it to make his fortune. Young Charles Nicholson certainly shook the cobwebs from the old town, becoming a household name before dying in poverty in his early thirties. But he also blazed the trail English flutes were to follow. Still narrow bored (his dad didn't have the facilities to muck about with the bore), so still reedy, and now you could push them due to the much better venting. Not uniform venting though, so the notes A and E stood out as weak compared to their neighbours. And still long-scaled, which was fine as domestic pitch was still low.
Rudall & Rose made flutes based on the Nicholson model and became famous. Whether they were as famous in their own time as now is yet to be determined. Their current fame might just be due to the accolades heaped on them by Rockstro, and thus by every subsequent writer.
Boehm's Ring Key conical (post 1832)
Stunned by Nicholson's power and tone, Boehm put the thinking cap on to develop a flute that might level the playing field. His 1832 conical was a nice flute, but too "nice" for the power-crazed British. Similar scaling and venting to the Nicholson's, the smaller bore just left it too lacking in drive. Too complicated and expensive too. But it set new standards for tuning.
Siccama (post 1847)
Siccama could no doubt see the weaknesses in both the Nicholsonian flute and the Boehm conical, and came up with a flute that avoided all the problems. Simple, powerful, well-tuned, effective and uniformly distributed venting, large bored, it had the power, the tuning and the quality of tone the English liked. He offered the manufacture to Rudall & Rose, but they foolishly turned it down, probably on Carte's advice, and took up making the conical Boehm instead. Siccama started his own manufactory and outsold the conical Boehm by a large margin.
Boehm cylindrical flute.
Boehm came back with his new cylinder flute, also in 1847. Big bored but badly vented, complicated and with a new fingering system, it was slow to take off, especially when hampered by some rather swift dodgy-dealing on the part of Richard Carte, rapidly becoming the supremo over at Rudalls. It needed a pinch of fairydust to make it really sing, and that didn't come until about 1862.
The necessary fairydust appears (at the time of writing) to have been supplied by John Clinton, and came in the form of a significantly better regime of venting. The modern Boehm has about the same level of venting as Siccama's flute, which is probably a rather late compliment to that much-maligned maker.
Pratten's Perfected (post 1852)
And then Pratten, unwilling to learn Boehm's new fingering system, made a last-ditch effort to save the 8-key flute. Starting with Siccama's fine design, he reverted it to an 8-key, and rescaled it to be more useful for professional musicians' use at High Pitch. He had to accept the same limitations Nicholson had run into - very non-uniform venting - but delivered a simple-system 8-key flute more in tune than any before it, big bored, big toned, generally well vented, and scaled sensibly for current requirements.
I think we can see that not only were there big differences between flutes of the first half 19th century, but also that we can relate their physical details with their musical outcomes. This can help us to avoid big mistakes, such as expecting a very long-scaled small-hole early 19th century flute to be able to argue its way in an Irish session. It can also helps us in deciding what style of flute we should base our modern flutes on. Looking at who actually did what and when also helps us to appreciate the work of some makers, like Siccama, who appear not to have been fairly recorded in history.
English flute making developed incredibly during the first half of the 19th century. The next fifty years were also turbulent, but the emphasis shifted away from simple-system flutes to more complex designs, for the most part based on Boehm's cylindrical bore.
More to come
That's it for the moment, I'm afraid. I'll be returning here as time permits to add more flutes and more perspectives to our comparisons.