In Reply to: Bat an eye posted by Terry Green on March 27, 2009 at 14:09:
: What id the origin of "bat an eye" (usually quoted as "did not bat an eye")?
In falconry, when a falcon or hawk "bats," the bird flutters it wings, "either from the pearch or the mans fist, striuing as it were to flie away." or so said Simon Latham in the book now known as Latham's Falconry .
In the 19th century, and presumably for some period earlier, batting ones eyes or eyelashes was a similar fluttering, like rapid serial winking. It was used in the negative to indicate a lack of emotion or indifference ("without batting an eyelash"), or in the positive one might say it of a coquette. ("How could I refuse, with her batting her eyelashes and all?") It has also been used in regard to sleeplessness. (I hardly batted an eye all night.)
Because the sources indicate the use in falconry long before that of the human eyelids, it is assumed that the earlier use is with falcons, and that the use with eyelids or eyelashes is an extended use. I'm not certain whether or not birds are nowadays described as batting their wings.
Ilearnt all this from the OED.