The whole page is taken up with the following notes:
Gerrard Leir[...]ss, in the principles | of Painting has asserted that | lights are always parrell <...> | and gives as an instance by the | Suns declining rays that no undr | part of a projection can receive the | Sun’s ray ... by the extreme dis- | tance and by the Theory that all | Lights are parralel only concludes | that never can appear to diverge | but when the rays of the sun enter | ing an aperture gives the size of that | aperture by an opposite plane, | but that is only point Blank, for | instance the rainbow gives and | illu[?mines] a wall immediately oposed | by immediately the sun rises or | sinks below the centre of the aperture | it increases because the plane
This is the beginning of a passage which continues on the recto of the leaf (
D07510) 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
The Art of Painting by Gérard de Lairesse (1640–1711),
2 in the English translation by John Frederick Frisch (London 1738 and later editions).
3 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).
4The key passages of Lairesse’s text (1738 edition) occur in Book V (‘Of Lights and Shades’). Chapter XV is headed: ‘Of the Sun’s Light upon Objects at Rising and Setting’. The chapter opens as follows on pages 229–30 (the italics are as printed):
It is unaccountable in many Artists, who handle an Art, whose Theory is built on Mathematics; its Practice, on Experience; and the Execution on Nature; that they take so little Notice of the three Points wherein lies their Honour; especially in the lighting of Objects in a Sun-set; for the Sun, how low soever, cannot shine on any Object under the Parallels, namely, not in the least from underneath, were the Object, if I may say so, as high as the Clouds; and yet we see many Paintings, wherein the Objects are, by a Sun-set, more lighted from underneath than above: which is contrary to Nature ...
