The attached are taken from Frege's Grundgesetze der Arithmetik
(Jenna, Germany 1893). Athough the symbol on the middle of the
second line looks like a U, the vertical strokes seem to me to
be too close together; I thought it might be a commercial sign
like the "per" symbol (unicode U-214C).
I'd be most grateful if anyone could tell me more about it.
Thanks in advance