It was searching for the name “Jack Engle” in mid-19th-century newspapers that put Zachary Turpin on to the “warm lead” that turned into a “white hot” discovery: A forgotten 165-year-old novel written by Walt Whitman. Turpin, a Ph.D. student at the University of Houston, already made history last year when he discovered hitherto unknown musings on “Manly Health and Training” written by the author of “Song of Myself,” ”I Sing the Body Electric” and “When Lilacs Last in the Dooryard Bloom’d.”