Clinton 1851 Model Flute Analysis


This analysis stems from a restoration project on a very rare flute by the mid 19th century English maker Clinton.  The instrument is believed to be of the type that Henry Potter entered into the Great Exhibition in London in 1851 on behalf of Clinton.  You may first wish to read the associated article about Clinton before proceeding with the analysis.

What can we expect to see in the Clinton?

From the historical record, we expect to find a conical flute, fingered essentially the same as were other conical flutes of the time.  But we expect to see the known defects of the 8-key flute dealt with, and the good points retained.  It would do us well to review the features and failings of post-Nicholson 8-key flutes before we see how Clinton fared. 

8-key features

  • dark, firmly focused tone

  • powerful tone

  • simple, reliable construction

8-key failings

  • E notes weak, veiled and unstable in pitch

  • F# notes flat, require opening F keys

  • A notes weak, veiled, tending sharp

  • C# notes flat, require opening C key

  • C notes veiled and tending sharp

  • D' sometimes unstable or unclear

  • limited 3rd octave response

  • difficult stretch between L2 and L3

  • difficult stretch between R2 & R3

  • very flat foot notes

Previous improved systems

Several systems had been invented post Nicholson to improve on the common 8-key.  We should review the directions they took ...

Boehm's 1832 Conical

While making dramatic improvements to the stretch and intonation problems, this instrument was not popular in England.  Detractors complained about its unfamiliar fingering and weak tone.

Siccama's Diatonic

Siccama's 10-key design kept all the best 8-key features, improved intonation generally and reduced stretch.  It was a very influential instrument, and lead ultimately to the Pratten's Perfected design of 8-key.  It did not deal with the flat C# and F# notes, nor offer significant improvement to the third octave response.  

Some later manufacturers of the Siccama system added a Brille mechanism to improve the C#.  The Brille consists of a duplicate upper c hole closed when either or both of L1 or L2 are covered.

Boehm's 1847 Cylindrical

This is the instrument that caused Clinton to get into flute development in the first place, so it's of particular relevance.  We find that Boehm's ingenious invention has solved all the technical failings of the 8-key.  So why was Clinton unimpressed?  For the same reason that many of us are today.  The new cylindrical design brought a markedly different tone to the flute.  Instead of dark and focussed, the new tone was bright and open.  The mechanism was also no doubt frighteningly complex to those familiar with building and maintaining 8-key and similar designs, adding considerably to cost.  It was also more intrusive and noisy.

So, How's the Clinton?

That's the question.  We'll get to it below, after we examine the instrument closely.

An examination of the subject

Let's look closely at the flute to see how it might work.  

The Clinton 1851 model flute with the Rudall Rose Patent head.

What did we find?

Firstly, a major dilemma.  While the body proclaims:


(Unicorn stamp)


and the Foot agrees:


the barrel argues:


More to the point, the head is unmistakably a Rudall & Rose Patent Head.  So was this normal, an option, a replacement or a mistake?  Determining that would have to wait for the restoration. 

  Turning now to the body and foot, we find a lot of the key-work is straightforward:

  • Long F, G#, Bb and upper c key are all functionally the same as for an 8-key flute (long F has touch broken off, upper c is missing).  The keys are however unusually long.

  • Short F is functionally the same as on an 8-key, but has been absorbed into the lower axle group.  The key cup is not visible in this image, but connects to the axle at the bulge just below the R5 ring-key.

  • R 4 and R 5 are simply extended upwards (the opposite of Siccama's approach, where R 6 is extended downwards).

  • The Foot keys are precisely as per an 8-key

More interesting stuff is happening in the upper axle group.  There are four holes, which correspond to the notes C#, B, a sharp Bb and A.  Note that these are in addition to the usual side-mounted C and Bb keys mentioned above.

Closer examination reveals:

  • Hole L1 has two covers - a lower perforated one, and a ring key mounted above it.  Both covers are closed together when L1 is applied.  This also closes the cover on the third hole.  The lower perforated plate can be closed separately by the ring key on hole L2.

  • An insert is missing from hole L2, but it would appear to be a typical wooden ring-key insert.  The dimensions of the cavity and the ring suggest that it might have been slightly conical.  A replacement was needed to make the flute function.

  • L 3 is not a hole but a touch.  It does two things.  It bears on the cover of the third hole, closing it and therefore the covers on L1.  It is also extended downwards to close the fourth hole directly.

The most interesting differences from 8-key practice revolve around hole 1. It varies in effective size depending on fingering. So for c#, it is fully open, while for either cross fingered c or as the vent for d, it is reduced in size. On the face of it, a very nice feature. 

The twin plates on the uppermost hole, shown with the lower plate artificially closed.

Note also the third hole, partially obscured by the touch for L3. It is normally open, and closed by either L1 or L3. It is mounted a little higher on the flute than the Bb hole and is also distinctly bigger than that hole.  It appears intended to provide added venting to C and C# notes.  It will be interesting to see what improvements this might bring.

The overall system

The schematic diagram below illustrates the overall system used in Clinton's 1851 model.  The ring key on L1 and the key to the left of L3 (both shown in blue) are connected together by being pinned to the key-shaft.

(Schematic diagram by Tim Gallagher, Seattle)

The rule at the top of the schematic marks where the vents for each note are placed.  The large gap between E and the foot notes suggests we will see some flat-footedness in the response.  

The restoration

Fortunately, with the exception of the missing bits, the body of the flute was in good condition.  The story of making replacement keys and pads can be found at Broken and Missing keys, Impossible pads.  For reasons that will become apparent, we won't go into the details of the repairs to the head here, but at The Rudall & Rose Patent Head.

Remaining restoration involved freeing up jammed keys, replacing worn cork tenon wrappings and key buffers, and resoldering a loose axle tube on the Eb key.  A replacement insert for hole L2 also had to be devised.  Fortunately, the dimensions of the cavity and ring key pretty much dictated what this had to look like.

With the restoration out of the way, attention could turn to determining how good a flute this was ...

The Patent Head Mystery

The big question of course was "Did the Patent head by Rudall & Rose really belong to this flute?"  Was this normal, an option, a replacement or a mistake?

There were no visual clues apart from the makers' names:

  • the timbers matched magnificently

  • the tenon diameter suited the barrel socket

  • the tenon length matched the socket depth

  • the top of bore diameter was within range for the head bore

  • the barrel ring was stylistically reflected in the lower foot ring.

Examining the intonation produced by the pair tells another story:

The blue 470 Hz trace is the response with the slide closed, the yellow 440 z response with the slide fully extended (31mm) and the pink 455 Hz trace with the slide set halfway.  

Clearly the fully closed performance is unacceptable:

  • C#5 is over a semitone above C#4

  • The discontinuity over the C#5-E5 break is unworkable.

With the slide fully extended, the response at 440 Hz is much better, but still not good.  All indications are we need to go still lower.  This is consistent with our understanding of pitch at the time - the options were High Pitch at over 450, or Low Pitch at 430.

Backing up this objective evidence was the performing qualities of the combination.  Although all leakages and other problems had been ruthlessly rooted out, the flute performed very poorly.  The reason for this is clear and significant.  It has to be remembered that, as a Patent Head slide is moved, the stopper is moved at the same time in a pre-determined relationship.  If the head isn't right for the flute, it's extremely unlikely that stopper and slide will ever be in the right relationship.  A wrongly set stopper gives very unfocussed performance - just what this flute-head combination displayed.

The flute, but with a more normal head

With that experience behind us, the flute was fitted to a McGee flute head and barrel combination.  These results were recorded:

Obviously the exact slide extensions needed to produce the pitches above will probably not reflect those of the original.  But we can see clearly that the best response comes around the 430 to 435Hz mark, as evidenced by:

  • a flat lower octave response

  • a second octave response well centred on the first octave average pitch

  • minimal discontinuity over the C#5 to E5 break

How this is determined is the subject of Determining Best Pitch.

The 430-435 pitch range seems perfectly credible.  British Low Pitch was 430Hz, with 435Hz the standard on the Continent.  

The Third Octave

Once a likely pitch and slide extension for the lower octaves had been obtained, attention could be given to the response of the third octave. This set of fingerings produced the best result:


Best Fingering

O,O O   O O O  ,
O X X   O O O ,
X X X '  X X X  ,
X X O   X X O  ,
X X X   X X,O  ,
X O X   X X X
X O X   O O X  ,
O O X   O X O  ,
O X X   X X'X
X X,O   X O O  ,
X X,X   O X X '
X O X ' O X O

Illustrating the deviations graphically ...

This is indeed a fabulous result for the period.  Notes up to the bottom of the fourth octave could be easily achieved, with one exception.  A6 (third octave A) is notoriously hard to control on late conical flutes.  It was achievable, but not easily.

So, the Verdict?

In a nutshell, a very fine flute indeed.  Clinton has kept the main feature that endears us to the English 8-key - the dark, focussed, powerful tone.  And, although his new mechanism is more complex than the collection of keys on an 8-key, it is not greatly so.  There remain few interactions between the keys, and so little to cause difficulties in construction and maintenance.

Clinton has also dealt with every one of the failings of the common 8-key flute listed above, and dealt with them successfully.  The flute is capable of playing accurately and responsively from low C4 to C7, using the familiar 8-key fingerings, with only a few notes more than 10 cents off ideal pitch.  Only one note, A6, proves hard to play and this it has in common with all the later conical designs.

So how did he do it?

Looking first at the power issue, compare these bore dimensions:

We can see that while Boehm, no doubt obeying his German sensibilities, adopted a bore smaller than those in general use in England, Clinton went to the other extreme.  Indeed his bore is bigger than any of the other flutes we have so far examined, including the mighty Prattens (not yet invented).

Now let's review the list of weaknesses that Clinton had to overcome, assigning his solutions to the problems:

  • E notes weak, veiled and unstable in pitch

Hole 6 moved down to its acoustically desirable position, and increased in diameter to equal that of other holes

  • F# notes flat, require opening F keys

Hole 5 moved up to its acoustically desirable position

  • A notes weak, veiled, tending sharp

Hole 3 moved down to its acoustically desirable position, and increased in diameter to equal that of other holes

  • C# notes flat, require opening C key

C# is normally flat because of poor venting.  To combat this, holes L1 and L2 are made very large.  Further assistance comes from the introduction of the unusual hole 3, also very large.

  • C notes veiled and tending sharp

Closing hole L2 is more than usually effective in flattening C# because of its large diameter.  Further, the ring-key link that closes the lower plate of hole L1 assists the operation by reducing the effective size of L1.  This would normally make the C very veiled.  C is kept clear-sounding by the added venting provided by hole 3.

  • D' sometimes unstable or unclear

In 8-key flutes, the top hole is a compromise between C, C# and D.  In this design, the size of the D vent is reduced by the lower perforated plate on L1.

  • Limited 3rd octave response

The large, well-distributed holes used throughout the flute (compared to its tapering conical bore) provides the venting needed to give an adequate third octave response.

  • Difficult stretch between L2 and L3

Overcome by the extension on L3

  • Difficult stretch between R2 & R3

Overcome by the extensions on R1 and R2

  • Very flat foot notes

Flat-footedness seems to be an issue that slowly disappears as we approach the 1860's.  Whether Clinton has made any particular strides here will need to be reviewed as more flutes are studied in the way this flute has been.  In any case, it is noteworthy that the bottom C is not flat at 430Hz compared with the body notes.  C# and Eb remain about 20 cents flat, with D about -10 cents.  These are not hard degrees of flatness to lip up.

Other points of interest

One of the interesting features of this flute - chamfering of the tone holes. This is a technique more commonly associated with oboe makers - the very small holes of the oboe in conjunction with the high sound levels tending to produce unacceptably high levels of noise and intermodulation products at the sharp edges of the tone hole. 
The use of this technique on some but not all tone holes of this flute suggests some careful thought and consideration has gone into it.

If you can assist us with any information about this flute, or have queries you'd like us to answer, please contact me!

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