The Collaborative International Dictionary of English v.0.48:

Memnon \Mem"non\, n. [L., from Gr. ?, lit., the Steadfast,
   Resolute, the son of Tithonus and Aurora, and king of the
   Ethiopians, killed by Achilles.] (Antiq.)
   A celebrated Egyptian statue near Thebes, said to have the
   property of emitting a harplike sound at sunrise.
   [1913 Webster] Memoir