The whole page is taken up with the following notes:
[?Define angles] to the eye to the horizontal | of which it is the great [...] so that | cat[...] that diagonal line of vision | would be seen on the water, but this | is a Theoretical, not a [?practical] conclusion | and tho I cannot define what is positively | [?irreglr] to do yet can most [...] only | what appears wrong. The [?apperance is] | that all reflections are equal only to | the object reflected, without defining | [...] distance position of the | diagonal or the square of ray of [?vision] | observation or that which is above | the eye of observation which is to be seen | in a [?reflected] mirror tho [?notable] by the | Eyes and [?that] a [...] | can define the multifarious [?power of]
The passage is part of a sequence of notes and diagrams which runs back from folio 79 verso (D07487) to folio 72 verso (D07473). The previous page of notes is folio 74 verso (D07477); the next and last is folio 72 verso (D07473). The semi-diagrammatic drawing of a boat on folio 81 verso (D07491) also appears to belong with these notes, concerned with sunlight or light in general in terms of reflections and the casting of light and shadow from polished objects or bodies of water. They relate to Turner’s fifth Royal Academy perspective lecture, on reflection and refraction.
Davies 1994, p.289.