To cross the riffle; metaphorically, to attempt a thing successfully.

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1859.  I guess they’ll make the riffle.—Mrs. Duniway, ‘Captain Gray and his Company,’ p. 235 (Portland, Oregon).

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1862.  See Appendix XIV.

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1875.  If I can make the riffle I want to git to Washington Territory yet.—S. J. Barrows, ‘The Northwestern Mule and his Driver,’ Atlantic Monthly, xxxv. 557/2 (May).

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1887.  (Lit.) We ran on, fighting the stream at intervals, but ‘making the riffle,’ or crossing the rapid, without resorting to bacon hams in the furnace or a nigger on the safety-valve, as was the custom in the palmy days of steamboat racing on the Mississippi or the Sacramento.—M. Roberts, ‘The Western Avernus,’ p. 202. (N.E.D.)

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1902.  I don’t want to kill a man fer jest tryin’ to steal an’ not makin’ the riffle.—W. N. Harben, ‘Abner Daniel,’ p. 230.

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