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Just over half the page is taken up with the following notes:
the Sun to be a Globe of fire, the difficulty | of making them accord to Gerard L[...] [i.e. ‘Lairesse’] | to be parallel is increased for if a Globe | of fire must according to known [?rules] of | light upon philosophical principles be | capable of giving light on all sides and [?altho] | the main body of light can be qua[...] only | in a direct line from [‘to’ overwritten] the circumference of the | disk yet the other rays must so [?intwine] | themselves with the direct light as to deny | the positive light to be the only one yet | it surely admits that the lights must be | increased
Below is a diagram of a disk throwing out intersecting rays in parallel bands horizontally, vertically and diagonally; compare the diagrams on folio 85 verso (D07499).
This passage follows on from the verso of this leaf (D07507), and continues opposite on folio 88 verso (D07505). It is part of a sequence beginning on folio 91 verso (D07511), and running 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