This is an early American hymn tune. Acccording to D. DeWitt Wasson's Hymntune Index and Related Hymn Materials (1998), SALTASH (aka PLEADING SAVIOR, PLYMOUTH, SING OF MARY etc.) appeared in Joshua Leavitt's The Christian Lyre (1831), Henry Ward Beecher's Plymouth Collection (1855), and The English Hymnal (1906). Marion J. Hatchett (in A Companion to The New Harp of Columbia, 2003, p. 33) also says that "PLEADING SAVIOR (SALTASH) goes back to Joshua Leavitt's Christian Lyre."

The Christian Lyre is "A Monthly Musical Periodical founded and edited by Joshua Leavitt (an American Presbyterian) in 1830. It is not known how long it continued in existence; a copy of an early volume in the Harvard Divinity School Library is marked 'Vol.1 3rd edn 1831.'" (From this page).