1851 Great Exhibition: Official Catalogue: Class X.: Robert Wornum
499. WORNUM, ROBERT, Store Street — Inventor and Manufacturer.
Improved piccolo pianoforte.
Semi-bichord grand pianoforte, upon the patent over struck principle.
[In the ordinary pianoforte action, the springs are struck from below, in this instrument the hammers strike down, hence the term overstruck.—H. E. D.]