Excerpts from Books and Wikipedia
"It is now considered clear, however, that Long was the first to use ether anesthesia during surgery." [1001 Days]
"On October 16, 1846, William Morton (significantly, a dentist by profession) successfully administered ether during an operation by Dr John C. Warren for the removal of a neck tumor at the Massachusetts General hospital in Boston."
[Howe: What Hath God Wrought, p. 474]