Body English

Perhaps you've heard of "putting english on" a ball to cause it's path to curve (See the Magnus Effect). What about this is English? Especially since it seems to be almost exclusively an American term. The English don't refer to it as english; they call it "side."

There are two possible explanations I like:
1. The first relatively widespread and dramatic ball curvature Americans were exposed to was thorough English pool sharks in the 19th century.
2. It comes from the French word "anglais," which refers both to the geometry concept and to the Angles who were early settlers of England (think Anglo-Saxon).   

The earliest example of the term in print seems to be by Mark Twain in The Innocents Abroad:
"the cues were so crooked that in making a shot you had to allow for the curve or you would infallibly put the "English" on the wrong side of the ball"

A similar sounding, but separate term is Body English. This describes the physical gestures the athlete may perform after releasing the ball to encourage it to follow the desired path. Our President demonstrates above.

This may be an expansion of the term above, in that both seek the same result though different means, or it may come independently from one's gestures being a kind of body language, or body English.