Figured Bass: add '×'-shaped 'accidental'

[mgavioli]

XVIII-c. French figured bass notation featured an '×'-shaped (pseudo)-accidental, not to be confused with a simple graphical variation of #.

Two examples; a page from M. Marais, Trios, Paris 1692, B.C. p. 44:

note the "4×" in the 9th measure of the second line.

And a page from Telemann, Quatuors, Paris LeClerc 1737 (40 yeas later):

Note the several "6×" across the page, some with a simple '6' and some with even a slashed 6 (already implying a major 6th); lastly at the beginning of the last line, even a "5×". Note also that both sources use a 'normal' # sign.

There is some consensus that the sign meant a major interval reached by 'some' accidental (either a sharp or a natural) in a context where '#' already meant 'sharp' and no longer generically 'major' as in previous times. Whatever the interpretation, it is rather clear that the sign is not used casually but has specific semantic content.