The whole page is taken up with the following notes:
Aristole first to consider this | and then proportion by means | answerable therto | if a figure is to be look 10 faces | it must be made 11 | In like manner and if the Art[...] | choose a Collos.. of 10 Cubits, and | the Head thereof shall loose one third | he must make it bigger by 3 | of the Head The gen rule to look | how much the whole looseth to be | distributed [?over...] the whole and | when the Head is [?shortened] it must | be increased <a>and this is the true | art.
Maurice Davies has identified these notes as transcriptions from the 1598 English edition of Giovanni Paolo Lomazzo’s Tracte Containing the Artes of Curious Paintinge Carvinge & Buildinge
(see the sketchbook Introduction)
in this case from chapter I, ‘The Proeme’, of ‘The Fifth Booke: Of the Perspectives’, pages 183–4. Lomazzo notes:
Wherefore the workman must ever beare in minde this principle of Aristotle: First to consider the end, and then to proportion his meanes answerable thereunto, ... if the distance shall cause it to loose one face, he shall adde something proportionably unto every face, so that if the image should be of 10 faces, he should make it of 11. increasing it by one face, and so will the eie judge it to be but of 10. faces. ... In like manner, if the artificer be to make a Coloßus of 10. cubits, and the head thereof (by reason of his distance from the eie) shall loose one third part of the head, he must make him bigger by the third part of the head ...
The generall rule is this, that looke how much the whole image looseth, all that is to bee distributed through the whole image. But when the head (for example) looseth something, and is shortened, it must be made bigger. ... And this is the true arte which the ancient observed ...
In terms of the folio sequence, this is the last page of Turner’s extensive notes from Lomazzo, though since he wrote with these pages turned vertically, they continue ‘down’ onto folio 61 verso opposite (D07459