John A. Lynch was a Chicago banker.
He is referred to in JW's correspondence about 1894-95. He bought Violet and Silver: A Deep Sea (YMSM 411) from Whistler, a painting which Whistler was somewhat lothe to sell. In 1896 he was staying at 147 Avenue de Villiers, Paris.
Eddy, Arthur Jerome, Recollections and Impressions of James A. McNeill Whistler, Philadelphia and London, 1903, pp. 274-75.