Grand piano, nr. 4650; 167 x 117 cm; 6 octaves; rosewood ¹

Robert Wornum built popular small upright pianos with many features in common with this unusual little grand. Its two part case resembles earlier uprights built in partnership with Wilkinson, ^{2, 3} neatly borrowing their mechanical strength and simplicity in a practical manner: stringing scale, bridge form, keyboard, action and trapwork parts also appear to be close to or identical with those implemented in Wornum other pianos. ⁴

The case is veneered in rosewood, vertical grain on the sides is continued onto both lid sections to an intersection at the hinge. Lid and keybed bevels are veneered, and veneer extends up to the natural keys. The cylinder swings up off center on sliding pivots pushed into case sides. Turned and faceted legs are rosewood or grained walnut, as are two carved blocks that disguise case joints to either side of the keyboard.

The six octave keyboard is 99cm wide with tails of d natural keys accommodating otherwise uniformly wide tails and sharp key levers. The left pedal shifts felt covered hammers and wippen pieces which are coupled through tape checks extended over hoppers. Average key dip is 7.5mm, hammer blow is 40mm and weights required to depress f natural keys with dampers disengaged ranges from 54g to 46g up the scale. Damper heads are counterweighed to less than 10g. Modern wedge felts are fitted on the lowest 28 but there are traces of secondary pieces. ⁵

Individually tied iron bichord stringing follows equal tension patent with uniform diameters and geometric progression in length, ⁶ with 26700N overall tension at 440hz. The lowest 19 notes are wound and installed on a separate bridge. Striking distance is 1/8 length between nut and parallel front bridge pins. Bridge height tapers from 19 to 16mm. Grain length of the 6mm thick soundboard is proportioned with bridge location, with liners across the front and spanned by 9 equally spaced ribs 15mm wide and 9mm tall.

Veneered backposts extend from hitchplank over the wrestplank level with case sides. Two rows of rectangular headed tapered tuning pins extend through the exposed end of wrest plank are normally covered with the music and light stand. ⁷ Short and long lid props hinge lengthwise between two posts. Another pivots in the base from the corner of the bentside against the hitch plank to hold the case open for service.

1. Drawings and measurements from 1836 pocket grand, serial nr. 4650 item K16 in the collection of Royal Northern College of Music, Manchester,England.
2. p.57-59, Colt, C. F. The Early Piano. Stainer & Bell. London. 1981.
3. A grand piano by Herz using similar construction is shown at http://www.pianosromantiques.com/herz.html
4. p.246. Harding, R. The Piano-Forte. Gresham Books. Old Woking, Surrey. 1978.
5. p.177. Harding
6. GB.4,660. R. Wornum. Equal Tension Stringing. 1820. http://www.geocities.com/threesixesinarow/pat/ljas.htm
   "One size of steel wire is used throughout but with covering wire of the right length to bring its note to the required pitch." p.362, Harding.
7. Similar string arrangement is seen in a piano by Cristofori, 1726 (Leipzig Nr. 170), fig.18. p28, Harding.
   These arrangements usually are only considered regarding the security of the strings against the nut, although like more common downward pressure systems like agraffes and capo bars they also allow more favorable arrangement for actions.

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