The whole page is taken up with the following notes:
suns ray [...] would through | [...] [?point] the form of the boats | figures by [...] the shades that it makes | upon the wall is [?reported] in every | respect and the shadow is inverted | and as weak as reflected lights are to | real lights owing to all the reflected | light of the sun beams interrupting | the direct power of the sun reflected | effulgence in the water and of course | all the day light that efulges upon | the atmosphere [...] and when then | the position of the ray, crossing rather | thus either [?parallel] or diverging but contrary | seems to my mind to strengthen for upon | the principle of parallel lines the contrary | rays would all produce shadow as they
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 78 verso (D07485), and the next is folio 76 verso (D07481). The diagrams on folio 78 recto opposite (D07484) and folio 79 recto (D07486) are relevant to the text here. 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.