Hi, Ruckers doubles have lower manuals lower by a fifth. (Hubbard registers gots more notes than their keyboards, though the pitch standards this accommodates are much closer together) Huygens proposed a transposing keyboards to give managable subsets of 31: > ...having made the keys that raise the jacks all equal in length, > height and width, whose width makes a fifth of that of an ordinary > key, place above [them] a movable keyboard, with points attached > below all [these] keys; which are well adjusted once, for > sounding the strings that one employs for each Octave, they will > be the same for all the Transpositions...I have had made in Paris > some few mobile keyboards, for placing above the ordinary keys of > Harpsichords, & making by this means many Transpositions, though > not all complete; & this invention was approved & imitated by the > great masters. - Hygens, Christaan. Lettre touchant le cycle harmonique; 1691. Harding includes: UK2562. Ryley, Edward - 1801 Scottish Record Office ref. ?.10; Ryley, Edward, 1808 FR1333; Erard brothers - 1812 FR1107; Roller,... - 1820 FR1380; Wagners, Jean-Baptiste - 1820 Austria; Bohm, Joseph - 1820 BE0904, order nr 133; Lacroix, Mathieu - 1830 Bavaria; Schidt, J and Greiner, Friedrich - 1831 UK6835; Fischer, Pierre Frederich - 1835 BE765, o.nr.123; Rouhette, Francois Joseph - 1836 BE2214, o.nr.1629,index nr.1188; Vanlair, Gerard - 1842 FR12376; Le Bihan,.. - 1843 UK10430; Mercier, Sebastian - 1844 UK10385; Hewitt, Daniel Chandler - 1844 Scottish Record Office ref. 10657; Addison Robert - 1845 FR3711, 3rd add.; Montal, Claude - 1851 UK11285; Wooley, Thomas - 1846 UK11261; Storer, Joseph - 1846 FR1888; Montal, Claude - 1846 - Harding, Rosamond. The piano-forte; 1933. Also you can check the Patent Office online, here are the relevant classifications to put into the search (be sure first to select "All years"): ccl/82/445 ccl/82/446 ccl/84/447 ccl/84/448 Which mean transposers, transposers with auxiliary keyboard, transposers with keyboard shifted, and transposers with intermediate parts shifted. This is the USPTO search page: <http://164.195.100.11/netahtml/search-adv.htm> These may return long lists of numbers without further explanation, but you can guess according to approximate dates - US1379 - 1839, US7292 - 1850, US106396 - 1870, US229066 - 1880, US424202 - 1890, US666138, 1901 (all piano stuff). If you run Windows you'll want the AlternaTiff plugin to view them, which can be downloaded free at <http://www.alternatiff.com/> Clark
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