The whole page is taken up with the following notes:
Lamazzo Definition of Perspective
Is a science of visible lines so that the subject thereof | is a visable line considing the genus species difference | and incedence [Lomazzo: accidents] of things. Geminus an ancient Mathem[...] [Lomazzo: writer of the mathematikes] | divid[...] them into 3 kinds Optica or Perspectiva – | Sciographica and Specluria [Lomazzo: Specularia] Optica [Lomazzo: he subdivideth] in 2 Physiologica | and Grammica
Physiologicall the elements of all vis [Lomazzo: visible] | things first direct visibility that is the direct beams | second reflected third Refracted as Water Glass | Grammica is the deliniations
Agatharchus Democritus and Anaxagoras wrote affirming that | herein consisted the whole art of shortening [illegible word inserted above] and removing of all | difficulties in the art
Jerrold Ziff has identified these notes, continuing from the recto of the present leaf (D07423), as free transcriptions from the 1598 English edition of Giovanni Paolo Lomazzo’s Tracte Containing the Artes of Curious Paintinge Carvinge & Buildinge (see the sketchbook Introduction).1 The first two paragraphs come from chapter III, ‘The Definition of Perspective’, of ‘The Fifth Booke: Of the Perspectives’, page 188, and the last from page 189. In paraphrasing, Turner rather reverses the sense of Lomazzo’s last phrase: ‘with all the other difficulties accompanying the same’.
Further passages of Turner’s extensive notes from Lomazzo appear later in the sketchbook. The passage here continues directly opposite on folio 42 recto (D07425).
The ancient Greek painter Agatharcus was said by the Roman architect Vitruvius in his Ten Books on Architecture (presumably Lomazzo’s source) to have painted scenery in perspective for a play by Aeschylus, the subject of later commentaries by Anaxagoras and Democritus.2 Agatharcus and Anaxagoras are also mentioned in notes in the Lowther sketchbook (Tate D07926; Turner Bequest CXIII 48a), and again, with Aeschylus and Democritus, in the Greenwich sketchbook (Tate D06728; Turner Bequest CII 4a); Agatharcus, Aeschylus and Vitruvius also feature in the Windmill and Lock sketchbook (Tate D08045; Turner Bequest CXIV 65a). All are roughly contemporary with the present book.