| Reference number | Title | Date |
| EC/1846/12 | Kay, Joseph Henry: certificate of election to the Royal Society | |
| MS/426/277 | Copy letter from Lord Northampton [Spencer Joshua Alwyne Compton] President of the Royal Society; to Lord Auckland [George Eden] | 20 May 1847 |
| MS/426/278 | Copy of the Memorial from Joseph H [Henry] Kay, Lieut R N, Director of the Magnetic Observatory; to the President of the Royal Society | 30 November 1846 |
| MC/7/74 | Letter from Joseph H [Henry] Kay, commander, Royal Navy, Melbourne, Victoria, to [Walter White], Assistant Secretary of the Royal Society | 23 May 1864 |
| MC/7/124 | Letter from Robert L J [Lewis John] Ellery, Directory of the Melbourne Observatory, Melbourne, Victoria, to Dr [William] Sharpey, Secretary of the Royal Society, Burlington House, London | 24 September 1864 |
| MC/7/123 | Letter from J H [Joseph Henry] Kay, Melbourne, Victoria, Australia, to [Walter White], Assistant Secretary of the Royal Society, Burlington House, London | 24 September 1864 |
| MC/7 | Volume 7 of miscellaneous correspondence regarding business matters, sent to the Royal Society | 1864-1866 |
| MC/9/560 | Letter from Joseph Henry Kay, Captain Royal Navy, Melbourne, Victoria, to [Walter White], Assistant Secretary of the Royal Society | 21 May 1873 |
| MC/10/30 | Letter from J H [Joseph Henry] Kay, Rose Hill, Forest Hill, to the Royal Society | 28 October 1873 |
| MC/9 | Volume 9 of miscellaneous correspondence regarding business matters, sent to the Royal Society | 1870-June 1873 |
| MS/119/2/105 | Second half of letter from Joseph Henry Kay, Magnetic Observatory Rossbank to Humphrey Lloyd, Trinity College, Dublin | 2 March 1842 |
| MC/10 | Volume 10 of miscellaneous correspondence regarding business matters, sent to the Royal Society | July 1873-1876 |
| MS/119/2/108 | Letter from Joseph Henry Kay, Magnetic Observatory Rossbank to Humphrey Lloyd, Trinity College, Dublin | 4 September 1842 |
| MS/257/3/2 | Letter from Joseph Henry Kay, Melbourne to Edward Sabine | 17 July 1869 |
| MS/257/3/1 | Letter from Joseph Henry Kay, Melbourne to Edward Sabine | 22 July 1862 |
| MS/119/2/103 | Letter from Joseph Henry Kay, Magnetic Observatory Rossbank to Humphrey Lloyd, Trinity College, Dublin | 16 January 1842 |
| MS/119/2/104 | First half of letter from Joseph Henry Kay, Magnetic Observatory Rossbank to Humphrey Lloyd | 2 March 1842 |
| MS/119/2/107 | Letter from Joseph Henry Kay, Magnetic Observatory Rossbank to Humphrey Lloyd, Trinity College, Dublin | May 1842 |
| MS/119/2/102 | Letter from Joseph Henry Kay, Magnetic Observatory Rossbank to Humphrey Lloyd, Trinity College, Dublin | 12 November 1840 |