arpsichords," Sibyl Marcuse[5]
discusses surviving examples that show how the second keyboard was
arranged. The upper keyboard was the principal one, with the lower
keyboard sounding a fourth below. The strings acted upon by a _c_ key on
the upper manual were sounded by an _f_ key on the lower; so, in
changing from the upper manual to the lower, the player would have to
move his hands to the left the distance of a perfect fourth in order to
strike the same keys, thus producing the downward transposition. The
compass of the upper manual was _E/C_ to _c'''_. Since the lower
keyboard was shifted to the left, space was provided for five additional
keys at its treble end. The apparent treble range of the lower keyboard
was therefore extended to _f'''_, although the lower _f'''_ and upper
_c'''_ keys worked on the same strings and produced the same pitch. Room
was also made for five extra bass keys at the lower end of the upper
manual. However, since short octave tuning was employed and it was
desirable to be able to use the same fingering in the bass on both
manuals, the tails of the _C/E_, _D/F#_ and _E/G#_ keys of the upper
manual had to be bent to the left in order to work on the strings played
by the _F_, _G_, and _A_ keys respectively of the lower manual. The
vacant space to the left of the upper manual _C/E_ was filled by a block
of wood. Hence the five extra bass strings not used by the upper manual
were those played by the _C/E_, _D/F#_, _E/G#_, _B_, and _c#_ keys of
the lower keyboard.

Of the 16 Italian harpsichords and virginals studied that ascend in the
treble to _f'''_, 13 range to _C/E_ in the bass, thus having exactly the
same compass as the lower (transposing) keyboard of the Flemish
two-manual instruments. Twelve of the 14 Italian examples having _c'''_
as the highest key stop on _C/E_ in the bass and are identical in
apparent compass to the Ruckers upper manual.

The correlation of compass and string length of the Italian instruments,
the statements of Praetorius, and the similarity of the Italian keyboard
ranges to those of the Ruckers transposing harpsichords have been
considered. A plausible conclusion is that the Italian instruments
extending to _f'''_ were transposing instruments sounding a perfect
fourth lower than the prevailing pitch standard. Adopting the
terminology used for orchestral wind instruments, these could be
referred to as harpsichords in _G_.

The evidence of the correlation between