1. The clef nobody wrote
Near the end of the Mazurka in B minor, Op. 33 No. 4, the left hand plays alone under a held pedal, and the two first editions print the same noteheads on the same lines with different clefs. Paris reads them in the treble clef as G and C rocking in the middle of the keyboard, with naturals on the Cs to say so; Leipzig reads them in the bass clef as B and E an octave and a sixth lower, the tonic and subdominant of the key. Chopin’s autograph, the copy Leipzig engraved from, gives the left hand a treble clef at bar 215 and then no clef at all to the end, although the last bar only makes sense in the bass clef, so a clef is missing and he never wrote it. Leipzig’s engraver supplied it at 217, Paris’s supplied none and wrote naturals on the Cs instead, and London kept Paris’s notes and put the clef at 224. We first followed Leipzig on the strength of the manuscript, then read the page again and found that it settles nothing. Read literally, the page gives Paris, and read by ear it could give either. So we print Paris, and the notes page shows both readings.
2. One wrong note, five times
The free engraving of the Scherzo No. 1 in B minor, Op. 20 that most people download has D♯ as the fourth eighth of the theme, and because the theme comes back five times, the slip comes back at bars 38, 158, 274, 422 and 538. Both first editions and both of the later editions the engraver followed have F♯, matching the octave above in bar 42. Every source agrees against the engraving, so we correct all five bars. The note is a passing tone, so the chord stays the same, but anyone learning the piece from that file has been playing a wrong note in the theme.
3. One sharp: minor or major
In bar 44 of the Mazurka in C♯ minor, Op. 41 No. 1, the phrase lands on an F♯ chord, and Paris prints the A without a sign while Leipzig gives it a sharp. One accidental turns a minor chord into a major one and recolours the three bars of dominant that lead to it. Both readings make sense, both fit the harmony, and neither print’s parallel bars settle it, so we print Paris, F♯ minor.
4. A 19th-century habit that a modern file misread
The Polonaise-Fantaisie, Op. 61 opens with an arpeggio that sweeps up from the bottom of the keyboard, and the Paris print writes each flat once per step and leaves the repeats in the higher octaves bare, as engravers then did. Read by the key signature, the bare notes in bar 1 are C, F and G, where the print means C♭, F♭ and G♭, ten notes of one arpeggio, and the same habit runs through 57 notes in fourteen bars. We print what the print means. Twelve other notes are true misprints in Paris, corrected to Leipzig, including a bar 65 where a stray flat and natural make no chord at all.
5. Where exactly is the flat?
Bar 296 of the Scherzo No. 3 in C♯ minor, Op. 39 has a chord whose type depends on the height of one flat. Leipzig prints the sign in front of a D♭ and C pair, level with the D, which makes the C natural and the chord a major seventh; Paris prints C♭, a dominant seventh that pulls toward G♭. A flat on D♭ does no work, since D♭ is already in the key signature, and Leipzig’s own parallel bars at 174, 218 and 306 have the dominant seventh, so we read the sign as engraved a step high and print C♭.
6. A♭ or A, for a whole passage
Through bars 89 to 117 of the Mazurka in C minor, Op. 56 No. 3, Paris and Leipzig disagree on one note the whole way. Paris has A♭ in the right hand at bars 89, 96, 99, 101, 103 and 117, and in bars 89 and 101 its left hand agrees, so bar 89 is A♭ minor and bars 101 and 103 an A♭ chord over C. Leipzig has A natural at every one of those points, which turns bar 89 into A, C♭, E♭, and in bars 99 and 103 puts its A4 against its own left hand’s A♭3. Each print agrees with itself. Both readings make chords. We print A♭, and the notes page names the Leipzig reading bar by bar.
7. C♭ where the engraving writes B
Bars 8 and 44 of the Étude in F minor, Op. 10 No. 9 sound identical whichever way you spell the left hand, but the spelling says what the chord is. The modern engraving writes six notes in each bar as B; both first editions write C♭. With B the chord had been read as a German sixth; with C♭ it is D♭, F, A♭, C♭, a seventh chord on the sixth degree, which is what Chopin wrote and what the harmony around it expects. Both first editions agree against the engraving, so we correct it.
8. The first bar of the Heroic
The Polonaise in A♭ major, Op. 53 begins with a rising chain of chords over the bass, and in Leipzig the second sixteenth of beat two carries an E♭ with no natural, which puts a whole step against the left hand’s C♯ and makes no chord. Paris prints E, which fits, so bar 1 prints that, and bar 5, which repeats the chain a half step higher, confirms the pattern.
9. C major or C minor
Bar 3 of the Prelude in C minor, Op. 28 No. 20 ends the phrase on a chord that many pianists play minor, with an E♭, and that the first editions print major, with the E natural from earlier in the bar still in force. The flat is in neither Chopin’s autograph nor any first edition; it survives as a handwritten mark in copies that belonged to his pupils, presumed to be his own correction. We print what the editions print, C major, and say on the notes page where the other reading comes from.
10. A beam stub, and A in the bass
In the Waltz in E major, B.44, the 1880 Breitkopf print has a beam stub in bar 59 where a notehead would be, and the bass note in bar 68 is A. We print both as the print has them.
11. D or D♭ in the last chord
The Scherzo No. 2 in B♭ minor, Op. 31 closes in B♭ minor, and in bar 544 the free engraving we started from prints D natural in the left hand, a major chord, while both first editions and Joseffy, the edition the engraver followed, print D♭ and the right hand opens the bar on D♭. Every source agrees against the engraving and the note clashes with the hand above it, so we correct it. In bars 326 and 428 the engraving has G♯ where both first editions have F♯. At 428 Joseffy also has F♯, so only the engraving has G♯ and we correct it. At 326 Joseffy has G♯ too, so we keep G♯.
12. Half a bar in D or D♭
The second half of bar 106 of the Fantaisie in F minor, Op. 49 is in D natural in Leipzig and in D♭ in Paris, five notes across both hands. With D natural the beat is a B♭ major chord, and with D♭ it is B♭ minor, so the phrase moves differently into the next bar. Both make a chord, and neither print’s own parallel bars decide it. We print D natural, and the notes page says that Paris has the minor chord.