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 | |
|---|---|---|---|
| Gore, Mr. John Ellard | Ireland | 1891 | 1910 |
| Gonzalez de León, Sr. Luis | Mexico | 1903 | 1914 |
| Goldie, Mr. John | Canada | 1890 | 1891 |
| Goldberg, Dr. Leo | USA | 1974 | 1988 |
| Frost, Prof. Edwin Brant | USA | 1906 | 1935 |
| Fleming, Dr. Sir Sandford | Canada | 1890 | 1915 |
| Flammarion, M. Camille | France | 1901 | 1925 |
| Evans, Rev. Robert O. | Australia | 1993 | 2022 |
| Espin, Rev. Thomas Espinell | United Kingdom | 1894 | 1934 |
| Elger, Mr. Thomas Gwyn Empy | United Kingdom | 1896 | 1897 |