Alan McGowan: Gaige, in Chess Personalia (1987) has an entry for Hubert Knott, but with only one piece of information, death in 1892 - no date/place of birth and no place of death.
He provides no source for that death date and the reason that he had difficulty in providing more details about the player could be because a player from Scotland, James Brown Knott (1825─1890), temporarily assumed the name Hubert while in the USA.
1849 Harrwitz, at Glasgow CC, plays blindfold against consulting partners Tilghman and Knott. (CG has this game.)
1850 James B. Knott on Council of Glasgow CC, as shown in report of the club's Annual General Meeting. (Glasgow Herald, 9 September 1850, p4.)
1851 J.B. Knott on Council of Glasgow CC, as shown in AGM report. (Glasgow Herald, 10 March 1851, p6.)
1851 census: James B. Knott (26), Professor of Music, living at 17 Cambridge Street, Glasgow with several siblings.
1854 Hubert J.B. Knott married Emma Remsen Pine at New York on 17 October 1854.
1854 a chess problem (No. 11) by J.B. Knott appeared on page 207 of the New York Journal for July─December 1854. (Google Books)
1854 There was published 'My Glenwood Home,' with music by Hubert J.B. Knott and words by W. Seaman Beare (an anagram of which is, incidentally, 'be aware names'). (Google Books)
1855 another chess problem, by 'Mr Knott of the Glasgow Chess Club,' appeared on page 247 of Frank Leslie's New York Journal 1855. (Google Books)
1855 census for New York State, Ward 4, Brooklyn, King's County, taken on June 7, there appears:
Hubert Nott (30), born Scotland, a teacher of music, resident for two years at current address.
Emma Nott (21), wife, born King's County, NY.
1857 The book of the 1st American Chess Congress 1857, and newspaper reports, refer to one of the competitors being Mr Hubert Knott (Brooklyn).
1859 Reports show that during Paul Morphy's visit to the Brooklyn Chess Club on June 16, 1859, he played two games with 'Mr H. Knott,' giving the odds of his Queen's Knight and winning both games.
Chess databases, including CG, give Knott's games from the 1857 New York congress, and at least one of the odds games against Morphy on June 16, 1859, but no later games.
Return to Scotland
1859 'James B. Knott, lady, and daughter' are cabin passengers on the S.S. Glasgow, which arrived on the Clyde on 6 September, having left NY on 24 August.
1861 Scotland census: James B. Knott (35), a photographic artist, is at 7 Hill Square, Edinburgh with his wife Emma (26), and daughters Zella (5) and Edith (1).
Further information about his 'new' profession is at
1863 Knott's wife, Emma Remsen Knott, died 6 December 1863 at Edinburgh. Parents listed as George Washington Pine, merchant, deceased, and Portia Charlotte Pine, m.s. Cheetam.
1890 James B. Knott died 3 June 1890 at 9 Antigua Street, Edinburgh; his profession was shown as teacher of music.
Family history details at https://www.ancestrylibrary.ca/fami... (ancestry tree)
I have submitted all this to the Chess Scotland archive, though it has not yet been uploaded.