I was working on a collection of 8 letters to a Rev. Cornelius Clifford, 4 of which were written by George Tyrrell, the "Catholic modernist". In one of the letters (this one by a Rev. Joseph Keating, S.J.), Clifford was referred to as "the American Tyrrell"! - this apparently in reference to some writing of his (and the comment was meant as a compliment). I had never before heard of Clifford, so I sought to find out a bit more about him.
Some facts: born in New York City 1859, died 1938. Studied at Fordham, Innsbruck, Louvain. Entered the Society of Jesus in 1879: left with permission in 1899. Was ordained only a year before, in 1898. Taught at Georgetown; Merriam Park, St. Paul, MN; Seton Hall; Columbia. Wrote a few things. We have three copies of one of his books (and, sure enough, one is signed): Introibo. A Series of Detached Readings on the Entrance Versicles of the Ecclesiastical Year. He wrote the article on St. Athanasius in the Catholic Encyclopedia. Apart from some other minor facts, that's about it.
Sources: The 8 letters mentioned above; The American Catholic Who's Who, 1938 and 1939 (Detroit: Walter Romig); The Catholic Encyclopedia and Its Makers (New York: The Encyclopedia Press, 1917); and apparently Clifford is not so notable as to have made it into our own Dr. Thomas Loome's doctoral dissertation: Liberal Catholicism, Reform Catholicism, Modernism. A Contribution to a New Orientation in Modernist Research ("Tuebinger theologische Studien, Bd. 14". Mainz: Matthias-Gruenewald-Verlag, 1979).