Cock-feather

Now place the Arrow on the string with the cock-feather uppermost, that is to say, the further side from the Bow, and the other two will slide over it, without being rumpled or discomposed, but place the cock-feather downwards, or next the Bow and the feather will go directly upon it, which not only injures the feather very much, but very soon takes it off;

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Take hold of your arrow by the middle, and place it under the string and over the bow, against which you hold it, by throwing the forefinger of your left hand over the pile or head of the arrow; then drawing your right hand back to its other end, or nock, as it is called, you look for the cock-feather; this found, you let the arrow, held between your finger and thumb, slide down the bow, and you fix it, with the feather upwards, on that part of the string which is exactly opposite the top of the handle.

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Yet, surely it standeth with good reason, to have the cock-feather black or grey, as it were to give a man warning to nock right.

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Upon the head was placed the red cardinal's hat, adorned with a cock-feather, its cords and tassels iron chains hanging to the ground, while through the brim a pair of buck-horns extended their curved points.

Source: wiktionary