"When writing about that instrument he [Cozio di Salabue] states there is 'un tasello sotto l'F della quarta bislonglo per riempire un groppo' [a patch below the f-hole of the G string to fill a knot along the grain]. This instrument is very likely the Salabue Francesco Stradivari presntly owned by James Warren, which exhibits a wood fill in precisely the same place. The fill is almost identical in appearance to the one on the treble side of the fingerboard in Le Messie."
Le Messie, Stewart Pollens, Journal of the Violin Society of America, Vol. XVI, No. 1, Flushing, NY
Count Cozio's Notes, June 3, 1816: "Measurements of my violin made by Francesco Stradivari in 1730, with label belonging to
his father. . . . Long and wide arching. The top is wave-like, and crossed by a rectangular patch under the F-hole on the G string in order to fill a knot. Back and sides have no grain. The neck is good work with tight grain. Under the back, two thicknesses are inserted in patches; the upper [thickness is] in the purfling, and the other out of it. The purfling does not turn up in the corners. Good and even voice, but not as strong as the other three [violins] made by Stradivari described above. Generally speaking the work is well done." (pp. 242-43)
Memoirs of a Violin Collector: Count Ignazio Alessandro Cozio di Salabue, Memoirs of a Violin Collector: Count Ignazio Alessandro Cozio di Salabue, Baltimore