String indicator for strings

[NeeraWM]

We are now used to strings being shown with Roman numerals, even though placing them above the stave is a recent habit favoured by the biblical devotion to Gould's manual.
Before that, it was very common to find "sul ..." followed by the name of the string in either Anglo-Saxon letters (A-D-G...) or in plain words (Re-Sol...).

While preparing a talk on cello schools—which I held on Saturday—I found how around 1830-40, in Germany, the convention was to write the string in Arabic numerals (1,2,3...) below the stave, in a bigger typeface from the fingerings, which were placed above.
Here is an example (showing a harmonic scale of C major on the cello):

Dotz Conf - 128.png (746.32 KiB) Viewed 11077 times

Could we try to pinpoint the moment when the modern convention started to be applied and by what publisher/publication?
French editions still use "sul..." today, but it would already be great if we could find when German notation stopped using that notation in favour of Roman numerals.
Thanks!

[NeeraWM]

I'm quite surprised there's been no intervention to this.
As a cellist who has grown up with "sul..." and Roman numerals, this was a breakthrough!
And it's in a relatively modern time, 1830, when notation was already very similar to ours!

[John Ruggero]

Just saw this, Neera. I don't have the foggiest, not being a string player, but I have long thought that a book that dealt with questions of this type would be very helpful to a wide range of musicians, editors, scholars. That is, a History of Western Music Notation from, say, 1600 on. There may be such in other languages, but I am not aware of anything quite like this.

[NeeraWM]

Thank you anyway John.
I hope to find some enlightening on this topic, and will report back when I do.