Mitchel 11.7.1797 at Joseph Johnson's / 1.12.1800 miss Mitchel at Sarah Elwes / 25.2.1801 again / 26.5.1801 Mitchel at Nicholson's / 21.6.1808 calls / 20.5.1831 Mitchel (Tyne Mercury) calls / 20.6.1833 seek Haughton & Mitchel / 21.6.1833 call on Haughton (Asiatic Society) / 22.6.1833 call with Rowbothom on Mitchel, A S
1801 at Nicholson's may have been John Mitchell DNB 1785-1859 army officer and writer, as the DNB states "In 1801 he was sent to a mathematical school in London taught by a Mr Nicholson".
1831 was probably Henry Armstrong Mitchell 1799-1854 publisher of the Tyne Mercury (bbti)
1833 someone connected to the Royal Asiatic Socirty (Graves Haughton DNB 1788-1849 orientalist was its secretary)
other possibles James Mitchell DNB 1787-1844 scientific writer / Thomas Mitchell DNB 1780-1845 classical scholar, with Byron visited Leigh Hunt in prison 1813