Café Florian, Place San Marc.
Pardon! Is Mr Whistler right in supposing, from the droll little irritation shown in Mr Hamerton's note, that Mr Hamerton is perhaps - another "Art Critic"?
1. 7 October 
Year date from address - JW was in Venice for much of 1880.
2. Philip Gilbert Hamerton
Philip Gilbert Hamerton (1834-1894), author, critic and artist [more]. This relates to a sequence of letters initiated by JW's response to Hamerton's article on Francis Seymour Haden (1818-1910), surgeon and etcher, JW's brother-in-law [more], which appeared in Scribner's Magazine in September 1880. It replies to Hamerton's letter of 28 September 1880 (P. G. Hamerton to JW, #11395). See also P. G. Hamerton to Editor, New York Tribune, #11397 and JW to Editor, New York Tribune, #04281.
The letter sequence was published in Whistler, James McNeill, The Gentle Art of Making Enemies, 2nd ed., London and New York, 1892, pp. 81-9.