Design for a clock with the face incorporated into a pinecone

Preparatory for the clock found on the lefthand side of the pier table in plate 64 of Piranesi's "Diverse maniere d'adornare i cammini," 1769.
This and Morgan drawing inv. 1966.11:106 are preliminary sketches for a clock and sconces that appear in related plates of the Diverse maniere. In the publication, the clock is shown beside a timepiece made for Abbondio Rezzonico, while the sconces appear above a table made for Cardinal Giambattista Rezzonico. This suggests that Piranesi may have intended to produce actual objects corresponding to the drawings, although none is known to have been executed. Regardless, the sketches represent Piranesi's use of natural forms in design, which he stressed were complementary to forms derived from ancient art.