Coggeshall was a mutual friend of the gambler and collector Richard A. Canfield and JW, around 1901. He showed JW photographs of Canfield's collection (see Canfield's letter to JW, 20 July 1901, #00524, and JW's reply, #00525).
Of the several possibilities for identifying 'Coggeshall' the most likely is the painter, engraver and photographer, John Ingersoll Coggeshall (1857-1912), who had settled in 1877 in JW's birthplace, Lowell, MA, and who painted seascapes along the Massachusetts coast.
Other possibilities include Walter Durfee Coggeshall (b. ca 1851), a civil engineer living in Kensington at the time of the 1901 census; and Chandler Hall Coggeshall (1843-1926), founder of the State Agricultural School, Rhode Island. The former could have known JW in London, the latter could have known Canfield in Rhode Island; however, John Ingersoll Coggeshall, as an artist with connections with Lowell and Massachusetts, and a photographer who could well have photographed Canfield's colelction, seems the best candidate. The only problem is that there is no other record of him visiting London in 1900/1901.
Kelly's London Postal Directory, 1893; UK Census 1901; The Coggeshall Farm Museum at http://www.users.nyc.pipeline.com (accessed 2004.6); Biography from Whistler House Museum of Art at http://www.askart.com (accessed 2004.6).