The whole page is taken up with the following notes:
of oposition becomes oblique.
[diagram of vertical and oblique planes with horizontal rays of light indicated]
The shadow appear to increase when | Sun is near the Horizon in breath [sic] and | in length, as when we walk the | lengthnng shadow appear longer as | it becomes more extended. Whereas if it is | continued the same size it must as | the extended more remote from the | vision it would appear smaller but | upon general princles of the true and | artificial lights we must for the sake | of perspecuity and avoiding all abtract [sic] | observations that tend to call in doubt as they | perplex the student and create an appear | of illaborate definitions, it will be better | to say all lights and shadows caused
This is the second page in a continuous passage beginning on the verso of this leaf (D07511), continuing on the opposite page, folio 90 verso (D07509) and on further pages back to folio 82 verso (D07493). John Gage has discussed these provisional notes (not developed in the perspective lectures) as an example of Turner’s close observation of natural phenomena,1 in this case the question of sunlight travelling in parallel lines or otherwise, responding to a chapter of The Art of Painting by Gérard de Lairesse (1640–1711), in the English translation by John Frederick Frisch (London 1738 and later editions).2 See under D07511 for a discussion of Lairesse’s text. Maurice Davies has registered Turner’s notes as ‘on light and shadow’, as part of a longer sequence running back to folio 72 verso (D07473).3
The centre of the outer edge is folded back, whether by accident or design, following the profile of the brass clasp attached to the adjacent back cover (D07354).