This Fraktur was used as mathematical notation by Frege in 1893, I would dearly love to know its origin. It is extremely close to the face used by J. H. Geiger (Lahr) in "Des Lahrer Hinkenden Boten neuer historischer Kalender für den Bürger und Landmann auf das Jahr 1883", used by Gilles Le Corre as the basis for his "1883-Fraktur". The differences are very slight, visible to me only in the roundedness and directions of the terminators and in the tightness of the upper and lower parts of the A and F. Hence I suspect that the above font is also due to Geiger, but an earlier or later version of that used in the "historischer Kalender". It would be too much to ask that someone has access to a specimen-book for Geiger (if such exists), but one never knows! Any other comments would be most welcome.