Strange Slash Notation at end of Chopin Ballade No. 1

[henryaz]

In some of the editions I've seen of Chopin Ballade No. 1, 6 bars from the end there appear strange slashes through the stems, in the middle of each hand's octave. (see attachment) They do not look like tremolo marks to me, nor do any performances I've heard play them as such.  What do they mean?

Thanks,
Henry

[roncesvalles]

I think this means to break the octaves as before (grace notes for the upper note of the octave in the right hand, and the lower in the left).   If you look at the Kullak edition of the Ballade at IMSLP, the entire measure is done with broken octaves, and I think that this notation is indicating that one should do the same.

[henryaz]

Yet the octaves in question are not broken in Parakilas' book (see attachment).

[henryaz]

Jan Ekier (wiki: Polish pianist and composer known for his authoritative edition of Chopin's music for the Polish National Edition) and Paweł Kamiński commented on these slashes here:

https://serwer1374796.home.pl/wp-content/uploads/2013/05/ballades_commentaries.pdf

They say of the ballade (emphasis mine):

Bar 258-259 The marking of the breaking of the octaves first with grace-notes and then with the help of diagonal lines indicates a gradual acceleration of the break, parallel to the poco ritenuto — accelerando marking, so that together with the start of bar 260 it would be possible to imperceptibly enter into ideally simultaneous and rapid octaves.

And notes further down how the diagonal lines were omitted in some laster editions.

I'll buy this.  I think it would be interesting to make this slash an addition to standard notation for piano.

[timothy42b]

I would definitely have played that wrong.

Usually when I see a slash on a quarter note I play two eighth notes, or a slash on a whole note means play 8 eighth notes.