Honorary Membership was limited to 10 from 1890-1900, and to 15 from 1901 onwards. Corresponding Membership was a lesser class of Honoris causa membership in the early years. A few honorary members, such as Barnard, were first made corresponding members for a short time before being recommissioned as honorary members.
| Nation(s) |
Start |
End | |
|---|---|---|---|
| Huggins, Dr. Sir William | United Kingdom | 1891 | 1910 |
| Christie, Dr. Sir Wm. Henry Mahoney | United Kingdom | 1891 | 1922 |
| Clerke, Miss Agnes M. | United Kingdom | 1891 | 1907 |
| Gore, Mr. John Ellard | Ireland | 1891 | 1910 |
| Newcomb, Rear Admiral Dr. Simon | USA | 1891 | 1909 |
| Denning, Mr. William F. | United Kingdom | 1891 | 1931 |
| Burnham, Prof. Sherburne Wesley | USA | 1891 | 1921 |
| Morrison, Dr. Joseph | Canada/USA | 1891 | 1898 |
| Proctor, Mrs. Richard A. | USA/Ireland | 1891 | 1896 |
| King, Dr. William Frederick | Canada | 1892 | 1916 |