To go along a log as a racoon does.

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1834.  Our northward course brought us to the first fork of Boggy, where we cut a sycamore and crossed on it; part of the log was under water, and it was an altogether slippery business, especially for Irwin, who had received a kick a day or two before, and was obliged to straddle the log, and as they quaintly call it in the west, “coon it across.”—Albert Pike, ‘Sketches,’ &c., p. 77 (Boston).

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1854.  A deep chasm had, reaching across it, a small ancient looking cedar log, which had either to be walked or cooned.—Letter to The Oregonian, Oct. 28.

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1855.  [He drove] his horse through the stream, while he “cooned a log” above it.—W. G. Simms, ‘Border Beagles,’ p. 96 (N.Y.).

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1855.  You will be relieved of your nag, and we will coon a log for the rest of our journey.—Id., p. 319.

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1886.  In trying to “coon” across Knob Creek on a log, Lincoln fell in, and Gollaher fished him out with a sycamore branch—a service to the Republic, the value of which it fatigues the imagination to compute.—Nicolay and Hay, ‘Abraham Lincoln: A History,’ Century Mag., xxxiii. 16 n. (Nov.) (N.E.D.)

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