I'm seeing this symbol in a couple places in a score I'm transcribing, and wondering what it means:
Next to the flat in each case is a colon symbol. It only appears in the cello part, though that may or may not be relevant. They are all on the same note, middle C, I don't see any on other notes. The piece is a simphonie concertante by Jean-François Tapray (1738-1822) in case that gives a clue for notation that may have been used during that time.
Does it maybe have something to do with C-flat just being enharmonic with B-natural? Though there are other C-flats in the same part (as well as some of the others) without the colon, so no idea what the difference would be.
I tried searching around but it's impossible to look for "colon" regarding musical notation and not just have every answer be a "repeat bar", which this is clearly not.
Edit: @phoog pointed out another example, this time in the viola part:
Still on a C - doesn't seem to happen on any other note.
Edit again: Just found another example, on an F in the principal violin part:
So much for the "only on C's" theory, but it does still follow the pattern of the flat being enharmonic with the natural of the note below it. I also think that lines up with my second example from the cello? At least the line is rhythmically the same, I'll see when I get to it.
Edit: Yet more examples were spotted by @Old Brixtonian, still on C's, but this time in the harpsichord part, and I found a few in the piano as well, which makes even less sense to me, since while the strings have the ability to bend notes to make them more harmonically pure, keyboards definitely do not (at least in that time period, and mostly still today though there are electronic instruments which can, as well as some weird experimental acoustic ones, but it's not a standard feature at all.)
Edit: Ack! Another one that throws the enharmonic theory out of the water, it's on a B in the first violin part:
Which makes it make even less sense because B is already flat from the key signature, so that's entirely redundant.
Note: For anyone curious, I've posted my simulated recording of this piece here:
For the record, I ended up just ignoring the colons and it sounds alright, so I'll just chalk it up to something they maybe needed back in those days that doesn't apply to modern tuning.