This study was made with the page turned horizontally. The mast and spar of the more prominent vessel is continued upwards across the gutter onto folio 60 verso opposite (D30116). There appears to be a domed building lightly indicated beyond. This is one of a sequence of views in and around the Adriatic port city of Trieste, made working inwards from the back of this sketchbook; see under folio 57 recto (D30109).1
See also Powell 1995, pp.66, 81 note 18.