Cook and Wedderburn 's note ( Works, 3.513) quotes C.R. Leslie's suggestion that the water as it 'approached the houses' might be calm enough to reflect houses, while in the middle of the canal the breeze might cause ripples. There Leslie cites the 'large Canaletto in the National Gallery' as a 'fine example'. He is referring to Venice: the Upper Reaches of the Grand Canal with S. Simeone Piccolo, painted by Canaletto in 1738, and acquired by the National Gallery in 1838.
In his response to Leslie, Ruskin ignores the reference to the National Gallery picture. Instead, Academy Notes ( Works, 14.220) offers in evidence the fact that his gondolier had been blown off his 'perch' by the breeze at his doorstep, thus proving the possibility of wind near houses.
This response by Ruskin is unhelpful. He does not address the point but seeks to ridicule it with an attempt to generalise about wind behaviour from a single anecdote, presumably at the Gritti Palace, which is, in any case, in an entirely different situation at the other end of the Grand Canal. Is Ruskin here, perhaps, maintaining a position based not on observation but rather on what he feels ought in theory to be true according to his statement of the 'seven most common optical laws to be taken into consideration in the painting of water'( MP I:333)?