Just over half the page is taken up with the following notes:
Hamilton opines about the distance of the P– | If the hight of the Eye 5F and the distance 20 then | the seat of all objects whose space is 160 or 180 Feet | of Picture can occupy no more than 1/19 of 5 Feet | this reaches within 6 of the V. Line the seat of Objs | 20 Feet in depth at the distance of 60 or 70 Y. must | be imperfectly seen
<Anap> Anamorphoses or Deform
Maurice Davies lists the whole sequence of notes and diagrams running from folio 15 verso to folio 18 verso (D40670, D07381–D07385 and this page) as taken from John Hamilton, Stereography, or, a Compleat Body of Perspective, in All Its Branches, London 1738.1 Turner could have consulted the copy at the British Museum (since transferred to the British Library, London).
In the first paragraph, the letters stand for various words or units of measurement: ‘P’ for picture; ‘F’ for feet; ‘V’ for vanishing; and ‘Y’ for yards. The source is a single paragraph on page 390, within Book VII, Section VI (‘Of the Distance of the Eye from the Picture’). Davies suggests that Turner has ‘confused feet and yards (and possibly inches)’,2 although the various units seem correctly transcribed. The passage is one of several on this subject noted from various authors.3
The final phrase is from the heading to Hamilton’s Book VII, Section X (‘Of Anamorphoses, or Deformations’), on page 397; there are no further notes from this section.