Diagrams of the third improvement from the specification of the English patent granted to Robert Wornum February 15, 1842, reproduced from the <i>Repertory of Patent Inventions</i>, October 1842 in Dingler's <i>Polytechnisches Journal</i> 1843
Robert Wornum (reproduction of patent drawing, uncredited and not signed)
1842
Figs. 29, 30 Plate 9, p.479, described in "Verbesserungen an Pianofortes, worauf sich Robert Wornum, Klaviermacher in London, am 15. Febr. 1842 ein Patent ertheilen liess. Aus dem Repertory of Patent-Inventions Okt. 1842 S.225." Johann Gottfried Dingler <i>Polytechnisches Journal.</i> vol.87. J. G. Gotta, Stuttgart 1843  <a rel="nofollow" class="external text" href="https://books.google.com/books?id=X_c0AAAAMAAJ&amp;jtp=452">p.452</a>-454