Terry McGee wrote:Now the problem with this conversation, and we've been here before, is that we're talking in useless vagaries. And this goes right back to Rockstro. What sort of starting point is "Some of the flutes made by the old firm of Rudall and Rose were marvels of ingenuity in this respect."?
To talk seriously about "chambering" we need to see detailed bore profiles, and we need to see a proposed datum line for the same bore without the "chambering". Otherwise, how do we know whether it's really been "chambered" over this region, or compressed over an upper region, resulting in an apparent chamber lower down?
So, here's the challenge. Someone, anyone, find us a bore that they feel is reasonable evidence of "chambering". Overlay a graph of said bore with a dotted line that you reckon would represent the same bore if it were not "chambered". And let us test alternative explanations for that bore and see where it leads.
I agree, but I believe I already addressed this point quite clearly when presenting graphs that illustrate the specific kind of chambering that occurs in Rudall and Rose bore profiles.
The specific regions I identified rise above pretty much any datum line you can reasonably imagine. They are localized peaks, not just relative to the bore profile of the tenon immediately next
to them, but relative to any reasonable trend line that you care to draw along the entire length of the bore. Unless, of course, you assume that the original bore was entirely different and much
larger across its entire length (maybe cylindrical, and it only looks conical now because of damage?) and has shrunken in a non-uniform way such that these small cavities are left in the same
specific location on all Rudall and Rose flute and not on any others. But this kind of argument stretches credibility beyond its limits, and certainly violates Hitchen's razor.
Your argument that the bore cavities I identified may be caused by tenon compression is completely blown out of the water by the following observations about the data:
1. They occur only at two of the three tenons in the Rudall & Rose bores profiled, and never at the head tenon. Why would the head tenons not exhibit these chambers, especially
when the head tenons are exposed to more wetting and drying action than the lower tenons, and when they often quite clearly exhibit tenon compression effects?
2. They occur on all of the 10 or so Rudall and Rose flutes profiled, and on none of the other flutes profiled, regardless of how much tenon compression the others seem to exhibit.
3. The cavities extend across the joint, with matching bore diameters on two separate sections of the flute, one of which has no tenon. You can verify this by the lack of vertical
lines in the graphs, showing that these Rudall flutes do not have discontinuities in the bore profile across joints, unlike the Potter flute you keep showing.
In answer to conical bore's observation, it may be nice to have X-Ray images of the bores, but the bore profile graphs really present the same information in a clearer way. You can view them
as an image of one side of the bore, but with the bore variations exaggerated (depending on how the axis are labeled) to make them more visible. When the graph line climbs up (i.e. the
values get larger as you go from a point on the left to one to its right) you have a section of bore that is expanding (not just contracting slower than the datum line suggests that it should!).
If you look carefully at the graphs you will see very few points where the bore actually expands when traveling from left to right. Of these, most have a discontinuity in the graph line,
indicating that we have moved from one flute section to the next, across a joint, and that the bore diameters do not match. These are NOT the cases I'm looking at. The ones that interest
me are those that show an expansion and do not show a discontinuity. These seems to occur predominantly (perhaps exclusively?) in Rudall and Rose flutes.
So, I encourage everyone to take a close look at the graphs and try to identify sections of bore that exhibit all of the following features: a localized expansion (i.e., the line climbs up), a set of
values that exceeds those of any reasonable datum/trend line you care to come up with (this would be a straight line you draw that approximates some non-chambered bore profile you care
to hypothesize), and no discontinuity (no completely vertical section in the graph line). Then see how many of the examples you identified are Rudall and Rose flutes. Make sure that
you look at the following graph which shows 9 Rudall bore profiles and comes from Terry's website. I linked to this graph earlier, but it did not appear directly in the thread. I'm hoping that
the localized bore expansions that rise above any reasonable trend line are pretty obvious. I think it is also worth noting that many flutes show bore expansions at the very bottom of the foot.
I contend that these too are intentional, and that they are likely formed by back-reaming.