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01 November 2018

37. Corroborative detail

I will begin with what was intended to be a digression, but has ended up taking over the post:

There is a charming detail of orchestration in the trio Three Little Maids from School in (Gilbert &) Sullivans The Mikado (1885).  Just as Yum-Yum, Pitti-Sing, and Peep-Bo are finishing up the refrain, they pause:
Three little maids who, all unwary,
Come from a ladies seminary,
Freed from its genius tutelary

And in that moment, with the whole orchestra falling silent, a bassoon bubbles into life.

That bassoon idea was an afterthought.  A glance at the composers manuscript shows not just a blank bar at this point, but that originally he had notated a rest (in ink).  The bassoon effect has been pencilled-in later:
SOURCE:  cropped scan of the 1968 facsimile of the autograph score of The Mikado, p. 143 (bb. 4046a)
And there does not seem to be any document to establish with certainty when it was added.  By the 1880s, Sullivans practice was to sketch the musical numbers (and here is such a sketch for Three Little Maids), and then transfer the vocal lines onto the pages of what would later become the full scoreruling in the bars as necessary, but writing in only enough to give a copyist a means of preparing a sort of rudimentary vocal score for rehearsal.  The numbers would not be done in the order of the show:  the choruses and ensembles generally came first, with the solos later.  Only after the whole of the opera was framed would Sullivan turn to the orchestration, filling in the blank staves.  When the full score of a number was complete, the orchestral parts could be prepared and the keyboard reduction for the published vocal score finalized.

Mike Leighs 1999 film Topsy-Turvy, which dramatizes the months preceding The Mikados premiere, missed the chance to realize this moment.  Although there is a scene in which Sullivan has an exchange with the bassoonist, we do not see him have a flash of inspiration in the pit, handing down last-minute instructions to gurgle away.  Fun as that might have been, it is probably just as well that no such scene occurs, as we do not know that this episode occurred in the rehearsals for the first production.  Then again, the bubbling bassoon figure is played in performance in the movie, when by rights it should not have been.  It does not appear in vocal scores until the twentieth century; but admittedly, Sullivan took nowhere near as much care with the published scores as Gilbert did with the published libretti.  The absence of the bassoon whinny in the vocal scores (and the distinct piano-only score, which derives from the vocal score) is not strong evidence of anything beyondas we know alreadythat it was not originally there.

Is it even the composers amendment at all?  I believe it is.  That the idea was an inspiration in the pitas characterized aboveis suggested by the notation in the manuscript:  the contour of the figure is there, but it is unclear what the pitches should be and one would certainly not guess from this scribble that the first note is d'.  This emendation his was not notated here for the eyes of a copyist; it appears to me to be nothing more than a hastily-added aide-mémoire to the composer of this addition.  Indeed, the strongest bits of evidence that this pencilled addition is indeed by the composer are 1) it is in the autograph, which in performances would have almost immediately been supplanted by a copyists conducting score of some sort; and 2) the bassoon is so imprecisely notated.  I would expect anyone else making such an interpolation to make it as neat as possible.  (In any case, the bassoon part needs the actual pitches much more than the full score does.)

For this to be Sullivan's own interpolation would require an occasion when the composer and his autograph score (not a company copy) were both together back in the pit to conduct a rehearsal, since this change could not realistically have been added during a performance.  As Sullivan generally did not often conduct after the opening night of an initial production, the possibilities for such an occasion after March 1885 are slim indeed.  He did, however, conduct the opening night of a revival at the Savoy Theatre on 6 November 1895, and he may well have rehearsed the company before that performance.  (Not having his diaries at handalthough they are extantI cannot answer that question definitively at the moment.)

Two tidbits suggest that this 1895 production (rather than the original) was the occasion for the change.  One is the account of Thomas Dunhill, in his Sullivan’s Comic Operas:  A Critical Appreciation (1928):
[C]ould anything show more witchery than the use of the silent bar, just before the end of two of the verses?  Was Sullivan afraid that it could never be silent enough when, on the occasion of rehearsing one of the revivals, he broke this silence by pencilling a little curling phrase into the bassoon players part?  This stroke is amongst the most delicious of after-thoughts, but it is not in the original score.  One would gladly hear the passage both ways, on different occasions.  [pp. 131f.] 
The second tidbit is that the 1893 full score of The Mikado published by Bosworth (a German firm  heavily backed by Sullivan) has the original gran pausa here:  the autograph seems to have been the source for the Bosworth edition, so if the amendment had been made by 1893, the lithographist preparing the new edition apparently didnt take it seriously:
SOURCE:  cropped page-scan of Kalmus reprint of Bosworth full score, p. 139, from IMSLP #30034 (bb. 4043)
(I was a little surprised to find the bubbling bassoon absent from the 1907 recording as well, but in that instance the music had been heavily rescored to be audible with pre-electric technology, and I wouldnt be surprised if the orchestration was done from the published vocal score, if not the Bosworth scoreboth of which lacked the figure in question.)

I have no doubt thatas Dunhill assertsthe idea is Sullivans own, but the case is not airtight.

As I say, all of this was supposed to have been a tangential point; I was going to introduce it because it seemed like an example of an musical detail conceived later than the rest of its context, perhaps suggesting itself to the composer because of the different activityconducting a rehearsal with orchestra rather than composing in silence at his desk.  There are many examples one might use to illustrate such second thoughts, but I had thought this would be a fun one because some years ago I noticed that on 12 March 1885,  two nights before conducting the premiere of The Mikado, Sullivan had conducted Beethoven's Symphony no. 4 at the Philharmonic Concerts.  What if (I had thought) the giggling bassoon line was suggested to him by a celebrated bassoon solo in Beethovens finale?  (Granted, Sullivan's line resembles better the figures in the finale of Mozarts Symphony no. 39, but never mind.)  Wouldnt that be loverly?  Only as I came to look at it more closely did I see that there was not enough evidence to connect it to the Beethoven, so then I might as well use any example I liked.  I just got stuck on this one.

Having let the tail wag the dog for so many paragraphs, I will let the dog bark briefly here.  A few evenings ago I played the first movement of Alexandre Guilmants first organ sonata in a recital of Scary Organ Music.  It is a piece I first came to know as his Premiére Symphonie pour Orgue et Orchestre, op. 42 (1879)hearing it (as mentioned in a previous post) in a splendid recording conducted by Yan Pascal Tortelier; only later did I learn that the work started as a work for organ alone, the Premiére Sonate pour Orgue, also Op. 42 (1874).  The piece works so well for organ and orchestra together that it is hard to fathom that it was not originally conceived that way.

Below is a stemma of sources for these two versions that I have been reviewing in recent months.  The shaded boxes are sources I have not examined; the red text/lines trace the transmission of the orchestral version, while the black follows the organ solo version.  It will be seen that there is a complex interrelationship between the two versions, as ideas that crept into the orchestration gradually make their way into the text of the solo versiona few in the second edition, a few more in the third.   (Double lines indicate reprints of the same text.)

By far the bulk of these changes are rhythmic articulations where the original (in so far as I can determine it) had only sustained chords.  Thus, at the conclusion of the first movement (here copied from the 1876 Schirmer edition, but the Bärenreiter critical commentary testifies to the same reading in the autograph), Guilmant wrote:
SOURCE:  cropped screenshot of Schirmer edition (IMSLP #290298), p. 13, showing I/353359.
In the second edition this passage already has some substantial changes (marked in red below).
SOURCE:  cropped scan of Leupold reprint of 2nd edition, p. 45, showing I/353359 (my hightlights added)
All of these, in fact, have their origins in the orchestration, the chords at bb. 355–56 rearticulated with an antiphonal effect between organ and orchestra, and the brass introducing the new figure at the final cadence (with consequently shorter note-values for those penultimate chords):
SOURCE:  cropped screen-shot from the first edition full score (IMSLP #245332), p. 43, showing I/354359.
Rather than belaboring this point (as I had originally intended to), I will confine myself to one additional examplea change which does not make it into the sonata until the 1898 third edition, although clearly comes from the 1878 orchestration.  Here is the opening of the first movement as in the Schirmer edition (and the reading is identical (save for French-language registration markings) in the second edition):
SOURCE:  cropped screenshot of Schirmer edition (IMSLP #290298), p. 1, showing I/13.
Now here is the opening of the first movement as in the third edition:
SOURCE:  cropped scan of Leupold reprint of 3rd edition, p. 1, showing I/12.
(And don't get me started about all those slurs.)  Again, the dramatic rhythmic punctuationwhich he has very cleverly accomplished by the engaging of a manual coupler to a chord already being sustainedhas its origins in the orchestration:
SOURCE:  cropped screen-shot from the first edition full score (IMSLP #245332), p. 1, showing I/12.
Clearly Guilmant liked the effects he had devised for the Symphonie, and he found ways of folding them into the Sonate.  This evokes The Mikadonot just the added bassoon in Three Little Maids, but also one of Gilberts lines of dialogue.   In Act II Pooh-Bah justifies his graphic embellishments to Ko-kos (entirely fabricated) account of executing the emperor's son thus:
Merely corroborative detail, intended to give artistic verisimilitude to an otherwise bald and unconvincing narrative.
(Actually, this takes us back even to Topsy-Turvy.  If the film missed the opportunity of highlighting a textual change of the score, it does in fact depict Gilbert making a textual change to the libretto during a rehearsal, adding the word otherwise to this line.  I am not aware of any evidence to support that, but it is a nice moment.)

If we take Pooh-Bahcorroborative detail to be ameliorations made after the fact to an original that was already sufficient in itself, then these details manifest that sort of corroboration.  Neither Three Little Maids or Guilmants organ sonata is bald and unconvincing in its original version, but I think the addition of a little corroborative detail paid off in both cases.

01 October 2018

36. What shall we tell the students?

In some ways, I feel that musicology is both my job and my hobby.  Im paid to be a musicologist (or maybe Im really paid to administer a department, but I have to teach something); I do musicology on the side, too.  With occasional exceptions, my bedtime reading and the books I take on vacation are musicological; issues of the Music Library Association journal Notes (which always has a few articles, but is mainly filled with reviews of books, scores, and other musical media) accumulate on my desk to take when I travel.  (Ive found that Notes is perfect for travel conditions, as the fairly short items can easily be interrupted at any momenta gate change, the refreshment cart coming down the aisle, etc.and resumed later without really losing the thread.)  Most of what shows up on this blog inevitably comes from the hobby side of my musicology interestsindeed, very little has actually concerned the textual materials that have been my own research focus.

But this is one of my rare posts from the job side, straight out of the classroom.  Its not that the others dont deal with issues that might be useful in a classroom, but I tend not to write about what I do in the classroom.  In the blog I often dive deep into geeky details, but in class I seldom wade into textual waters, maybe for fear of drowning in digressions, or of scaring my students away.  But there are times where a textual matter is so centrala veritable elephant in the roomthat it must somehow come up in class.

I have usually taught music history classes without a textbook as such, using anthologies insteadone of scores and one of primary sources.  (For years I did this happily pairing the W. W. Norton survey score anthologies with the Weiss/Taruskin Music in the Western World source readings.)  More recently, my approach to music major courses has changed so much that I find no text worth my students money, and so I have sometimes opted to make my own anthologyparticularly with the easy access to public domain editions via the IMSLP.  I have kept my eye on the products out there, though, so I know pretty well what I am foregoing.

The only thing that I dont like about the Norton anthologies is that they have recently opted sometimes to computer-set an item anew rather than reprinting an early edition.  Here is an example:
Source:  scan of Norton Anthology of Western Music (6th ed., 2010), pp. 2389. 
I know that the notation of an early edition might be unwieldy for students, but it is not so foreign as to lose them completely.  (For example, here are the relevant pages of a 1679 printing of the Geneva Psalter, and a 1635 Scottish Psalmes of David in Prose in Meeter).  On the strength of the maxim about the value in teaching someone to fish, I would rather have the occasional difficult source in the classroom than always predigested texts.  Granted, the Norton anthologies do not generally seek out give original sources to reprint, but why re-set these here when the early printings could be such a handy teaching tool and take no more space?

Enough quibble about Norton.  A far larger disservice to students has been done by the competing Oxford Anthology of Western Music, three volumes conceived as an ancillary resource for the textbook version of Richard Taruskin's Oxford History of Western Music.  Whatever one might say about Taruskins accomplishment (and many people have... including the bloggers of The Taruskin Challenge), he is a significant voice.  Whether adopted or rejected, his retelling of the story of Western music will inevitably influence the classroom (and music journalists, for whom he seems to have become a one-stop shop), despite his particular interests and lacunae.  If Oxford University Press has its way, Taruskins version will supplant all others for the next generation.

My criticism in this post has to do not with Taruskin but with the companion score anthology, which was prepared by others.  As far as I can tell, the editors haveunderstandably—resorted to public domain editions as often as possible to keep the costs down.  I have no problem with this:  I am convinced that you can teach effectively from any source (although some sources are better in one context than another); furthermore, in a music classroom there is no such thing as a bad edition, as long as we consider what precisely that edition can teach us.  What frustrates me is when the editors fail to realize the value of the eccentric edition they have chosen to reprint.  I will offer two examples here.

First, BeethovenPathétique Sonata, op. 13:
Source:  cropped scan of Oxford Anthology of Western Music (2nd ed., "2019" [sic!]), Vol. 2, p. 204.
The Oxford anthology reprints the old Breitkopf complete edition (although bar numbers have been added and the layout is altered to fit more systems on the page).  This is a work for which no autograph manuscript survives, so that the first edition (1799) is the most authoritative source, despite the occasional likely misprint.  One significant aspect in which some subsequent editors have departed from the text of that first edition is the placement of the exposition repeat:  is the pianist to go back to the beginning or to the Allegro di molto e con brio (b. 11)?

SOURCE:  bb. [1113] cropped from the IMSLP scan of the 1799 first ed.
The first edition places this repeat at b. 11.  To be sure, there may be good musical reasons for wanting a reprise from the startanalogous to the Tempo I section which begins the development (b. 133)but that is not what the first edition shows.  In his edition, Jonathan Del Mar concludes There can be no [textual] justification for taking the repeat from bar 1, as has in some circles become fashionable (p. 26; the bracketed emendation is mine). The Oxford anthologizers have missed a chance to remark on this textual detail, and it is a good "teaching moment" lost... or at least inconvenienced, as now the instructor would have to know of this discrepancy in order to point it out, if someone in the class doesnt notice a difference between the text on the page and a recording they might hear.

Second, the overture to Rossinis Barber of Seville:
Source:  cropped scan of Oxford Anthology of Western Music (2nd ed.), Vol. 2, p. 281.

Oxford reprints this from a 1900 G. Schirmer piano/vocal score.  It includes a very common textual variant in the first theme of the Allegro:  the opening motive is immediately repeated note-for-notewith three pick-upsrather than with only two, as here in a Choudens vocal score of 1897:
SOURCE:  bb. 25-28, cropped scan of 1897 Choudens piano/vocal score "Edition conforme au manuscrit de Rossini", with piano reduction credited to L. Narici; scan from IMSLP 280519.
According to the critical commentary of the new WGR edition, the three-note echo appears in no authentic source of il Barbiere (1816), although Rossini had apparently previously altered the text thus when he used the same overture earlier in the year for Elisabetta, regina dInghilterra.  (He was recycling it there from Aureliano in Palmira (1813), which had the two-note version.)  Rossinis regularization mystifies me, as it is the lack of conformity that seems to me truly ingenious:  I am struck by the way in which the omission of a single eighth-note makes the whole passage seem less cluttered, less fussy.  The original is the harder reading, and it is no surprise that copyists would knock it back into conformity.  Whatever Rossini thought in the meantime, when it shows up again in Barbiere (here) the extra pick-up is gone, and the original text is restored.  But you wouldnt know that from the Oxford anthology, where no mention of it is made at all.  Do we tell the students?

Perhaps these are nothing more than missed opportunities.  Most troubling in the Oxford anthology is the cavalier identification of some of the sources in the first volume.
Source:  cropped scan of Oxford Anthology of Western Music (2013), Vol. 1 p. 530.

It appears to me that whoever put this list together regarded its purpose as to indemnifying the publisher rather than citing the sources.  To say merely that items 56, 68, 7073, 75, 76, and 7891 are public domain tells us nothing about the identity and, consequently, the quality of the texts before us.  Some of these are newly typeset by OUP (although what the source text was, or how much intervention has occurred, is not shared).  Others are lifted from major nineteenth-century editionsDenkmäler deutscher Tonkunst, the Bach-Gesellschaft edition, and the likeand as such they represent a variety of different editorial approaches (including the piano reductions included on the full scores of the old Handel edition).  Why these editions are not identified is a mystery to me, unless no one thought any of this mattered.  It does to me.  And it should matter to students, as I daresay their instructors would never let them get away with citing a source merely as public domain.

But its not like I have been a paragon of textual transparency in the classroom.  For years I have had indistinct qualms about an example I have taught in which there is a huge textual departure which I never mention to my students.  I have regularly used the last portion of Act III of Le nozze di Figaro in my core-curriculum music course (the sort of course that has generally supplanted 
appreciation courses).  Even though the bit of the act I assign in the course starts just before the dictation duet (Canzonetta sull'aria), I have found it useful to screen the whole of Act III for the class.  It takes about 40 minutes, and so with a few minutes of contextualizing, and occasionally interrupting to make some comment about form or technique, it just fits in a 50-minute period.  The students always seem to enjoy it.

SOURCE:  DG website
For this screening I have regularly used the 1993 Jean-Louis Thamin stage production (for the Théâtre du Châtelet), featuring the team assembled by John Eliot Gardiner, and released on DVD by Deutsche Grammophon in 2001.  I like to use this production because it looks pretty traditional on stage, but the stage business feels very current even after 25 years, and the students seem to relate pretty well to the singers-as-characters.  (It has a spectacular cast, too, with a young Bryn Terfel as Figaro.)

What I have always failed to tell my students, however, is that Gardiner modifies Mozarts sequence in Act III to accord with a hypothesis of Christopher Raeburn and Robert Moberlyessentially moving the Countesss aria to before the legal proceedings.  This scheme puts two soliloquy scenes back to back and removes altogether any solo numbers from the second half of the act.  Nonetheless, I like the pacing, and I think it works very well in that production.

Raeburn and Moberly published their idea in Music & Letters in 1965, at a time when Mozarts autograph score of Acts III & IV was still missing as a casualty of World War II, but even among various copyists manuscripts and printed libretti they could produce not even a single document that would support them.  Subsequent scholars (in particular, Alan Tyson) have revisited the hypothesis now that the autograph has resurfaced, and still there is no documentary evidence to back it up.  As sensible as the revised Act III sequence is, it never seems to have been part of da Pontes or Mozarts plan for the piece.  And yet this is the version I show to my studentsand with no comment from the lectern to say that this is an eccentric ordering of the material.  
(Granted, I dont show the class Act IV, where Gardiner makes an even more daring departure from the text, bisecting a recitative in order to reposition later numbers in the midst of it, but even then Im not sure that I would mention it.)  

My vague qualms notwithstanding, Ive never lost any sleep about my silence in class about any of this.  Although (as should be clear from my blog) text is a matter of enormous import to me, the textual situation isnt what Im trying to teach in that particular general-education context.  I want my students to be moved, amused, shocked, transfixed by Figaro and by that performance of it.  In another contextthis one, for examplethe textual issue is my subject.  I expect that most of my students wouldnt care about the manhandling of Mozarts score.  Even if one did, given a 50-minute class period for a 40-minute act, I have no time for it, and it is scarcely worth returning to at the next class meeting, particularly when it isnt even the assigned portion of the act.  (Then again, I also dont tell them that the fandango in the Act III finalevery much part of my assigned section of the pieceis absent from most of the early Viennese source, apparently cut after just a few performances.)

I remember once hearing a senior scholar respond to a graduate students idea, Well, that's something you might tell undergraduates.  I hated that.  I understood what he (sic) meantsomething like that is a hideously oversimplified explanation, but it is pedagogically useful as it is easily understood and would allow you to move on to other material.  I dont ever want to condescend to my students like that.  But I also dont want to obscure the subject by belaboring them with my textual hobby.  While it is fun to have a hobby and a job that so closely intertwine, Ive got to keep the two distinct enough that the everyone in the room is aware if I am momentarily digressing (or transgressing, really) into the hobby territory.  Such transgressions can be valuableas sometimes I have had to see someone being passionate about something in order to understand why it matters.  And I dont mind being geeky if my students can understand why I care about something.  Actually, I just dont mind being geeky.

My conclusion is so trite as to not need saying, perhaps, to anyone but me:  What shall we tell the students?  Whatever works.

01 September 2018

35. Out of order

For me, the most important reason to look at a composers manuscriptor (more likely) a scan or facsimile of itis to understand something about how it came to be written.  Compositional process (to use the musicological jargon) is always at least interesting to me, and it can sometimes be riveting.  Often you find that a piece that you know well as it is was nearly very different.  (I keep promising I will blog about Mendelssohns Italian symphony in this regard; indeed I will, but I just need to find time to re-read John Michael Coopers excellent study of it.  But there are very many examples of less extreme but still significant revisions in the standard repertory.)

This months post concerns just two instances where a composer decided to insert or re-order material, so that the manuscript presents the music out of sequence with what became the composers intended text was.  That’s not to say, of course, that (given time) the composer might not have changed it again, reverting to the original sequence or inserting or reordering new material.  Whatever one might say about the Fassung letzter Hand, its very “lastness makes it a handy reference point.  For example, in the discussions below I will refer to the bar numbers of the texts as we have come to know them, not as they appear in sequence in the source.

A cropped view of the third page of the autograph score of first movement of Mozart's c minor piano concerto; Mozart has marked the score to indicate that additional measures (written on a subsequent page) are to be inserted between the measures we now know as 43 and 63.
SOURCE:  detail of Mozarts autograph of K. 491/i f. 2r, 
showing  bb. 40-43 and 63-66.  The autograph is held by the
Royal College of Music, London, as RCM MS 402, but this scan is
from the 2014 Bärenreiter facsimile of the score.  

(A 1964 black-and-white facsimile is freely available on the IMSLP.)
An interesting instance of inserted material occurs in the first movement of Mozarts gloomy, glorious C minor piano concerto, K. 491.  As seen at right, Mozart originally followed the bar 43 (as we number it) with the bar that later became 63that is, he made a nineteen-bar insertion at this momentand a gorgeous one it is, with the duet of descending figures alternating between flute and bassoon.  He thus continues the subdued mood a little longer before the outburst that he originally planned at this moment.

I have mocked-up an audio example of this juxtaposition, although of course we can't know that it would have sounded like this:  Mozart generally orchestrated in layers, adding instruments one at a time, and so he might have scored this a little differently if the passage beginning at b. 63 had really been at b. 44.  But if you want to hear the text with the nineteen-bar cut, its on my soundcloud here.

The insertion of a new idea leaves this opening ritornello in a particularly awkward state in the autograph, requiring a jump forward to find b. 44, a jump backward to find b. 63, and a consequent jump forward again to find b. 90.  Moreover, as portions of this are reused again as the closing ritornello (which Mozart indicates with a dal Segno (in this instance, a cartoon head facing back toward the beginning) and other markings), one page of the autograph (f. 3v) contains bb. 54–62, 91–98 (re-used as 501–508), and 99.  But this is an extreme case, and Mozart leaves no doubt about his letzter intended sequence of bars.  (And, so far as I know, no edition has ever screwed it up.) [See Addendum below.]

As I was working on the previous post about bar numbers, my research took me to a page that I would nominate as perhaps the single most interesting page of extant Handel manuscript.  (I may well be wrong:  I have had my eyes on perhaps 5% of Handels extant manuscriptsmostly in facsimile or scansso I can hardly claim to any authority.  Moreover, I would welcome nominations for other contenders for that title.  By all means let me know.)

Anyway, my nominee for that distinction is this page, which has the conclusion of the second movement of the organ concerto published as Op. 7 no. 5 (HWV 310):
A page containing the last thirteen of the two-bar variations that make up the second movement of Handel's g minor organ concerto, opus seven number five.  This page of Handel's autograph has sections added in the margins after the main text was completed, and the two-bar units have been numbered to indicate the ultimate intended ordering.
SOURCE:  page from Handels autograph for HWV 310 (Op. 7 no. 5), mvt. 3; British Library R.M.20.g.12, f. 69v
Handel dated this manuscript, indicating that it was completed on 31 January 1750.  Then again, what does completed mean?  The alterations on this page might well have been made after that date.  The dating is a minor consideration, however.  The real question is What happened here?

This movement is a set of variations over a ground bass.  (Here’s a good recording by Lorenzo Ghielmi with La Divina Armonia.)  While it would not be fair to say that the variations could work as effectively in any order, this movement is clearly highly sectionalized into two bar segments, eighteen in all (with many of them immediately repeated).  Handels autograph shows that at some point after finishing the movement with just fifteen segments, he added three more.  He also (at the same time?) re-ordered the intended sequence by numbering each segment.  The first four segments are on the preceding page, so this page starts with the fifth segment.  The following illustration is intended to clarify what the autograph reveals:  the sections shaded in red were (I argue) the original version of the movement, proceeding in their original order (left-to-right, top-to-bottom).  The shaded sections in blue were added subsequently, and the numbering shown incorporates the new variations into a re-ordered sequence.  (The bar numbers indicate the final form, as do the bold variation numbers.)
SOURCE:  my own schematic offering a hypothesis about Handels original sequence of the variations as presented in the autography; a recording edited to manifest this sequence (and omitting the blue sections) is available here on my soundcloud page.

There is a logic to Handels revised ordering: the first three sections (3-4-5) are melodic, but thereafter there is a series of showy 32nd-note patterns, first arpeggiations in each hand (6), then scales in one hand or the other (7-8-9); then, starting at the mid-point, a stretch of new melodic ideas with more daringly chromatic harmonies (10-11-12); then, by way of a Scotch snap [short-long, with the short note in a metrically stronger position] figure (13), there are three sections with triplet figurationright hand, left hand, both together (14-15-16); the ending of the movement consists of the most brilliant of the 32nd-note arpeggiation patterns (17), and a grand chordal peroration (18).

There is, however, also a logic to Handels original version, which is not at all stream-of-consciousness.  (The variation numbers here refer to the final version.)
  • melodic introduction (3–4–5)
  • triplets (14, 16)
  • more chromatic melody (10–11–12)
  • “Scotch snap (13)
  • 32nd-note figures (7, 9, 17),
  • chordal coda (18)
In the original version the triplet sections come before the central chromaticized melodic passages, andin a move commonly seen in Baroque variationsthe speed of the ornaments increases as it nears the end, with (in this case) a series of three 32nd-note variations.  It is notable that the three (blue) sections that were added later each feature the left hand, which was apparently not emphasized in Handel's original conception of the piece.  Indeed, I think it not too fanciful to suggest that even the (inner-line) left-hand triplets in variation 16 were added as part of the revision:  they seem to my eye squeezed into the staves in an already sufficient texture.  (I note that in Simon Prestons recording, which I was using for my cut-and-paste version on Soundcloud, he leaves out the left-hand triplets on the first time through this variation, adding it in only for the repeat.)
cropped scan of the same page shown above; this shows the only variation to have two running lines (right hand and left hand) above the ground bass, but the cramped notation suggests that the left hand line was possibly a late addition.
SOURCE cropped to show detail of the same page given in full above
It is not at all unusual that such reordering and insertions occurred:  this is the way we write.  Having written, we may then proceed to move chunks of prose around hither and yon as it seems better to usas we have new ideas and second thoughts.  I was surprised, however, to find such clear evidence of Handels revisionsand delighted to try it out another way.

Addendum  30 September 2018

After reading my post, one of my mentors from Cornell, David Rosen, mentioned to me the very interesting case of the first movement of Mozarts last piano concerto, K. 595, about which David had written years ago in The Journal of Musicology.  In that case, Mozarts insertion of seven bars into the opening ritornello happened much later in the compositional process, in that it doesnt get notated until the closing ritornelloand, indeed, all editions before the Neue Mozart Ausgabe neglected to insert it after bar 46.  Davids fascinating article argues that the version known before the NMAs text exhibited a formal quirk that did not accord with Mozartstandard operating procedure in concerto first-movementsthat procedure as outlined by Robert Levin and Daniel N. Leeson in the Mozart-Jahrbuch 1976/77.  The thesis of Davids article applies just as well to K. 491, too:  that Mozart inserted material to accord with the ways things had worked well before.  In both of these cases (and who knows how many others?) his first thoughts deviated from his well-trodden path, yet in both he eventually settled on something more conventional.