Ford circles are a collection of horocycles in ℍ used by Ford to study continued fractions in papers such as [2, 3]. […] Two Ford circles intersect in at most a single point, and the interiors of the two circles are disjoint. In fact, one can check that the Ford circles C_a/b and C_c/d are tangent if and only if |ad-bc|=1.

(historical)

Arthur Carlson, New Yorkian Specialist, 503 Fifth Avenue, New York.

Shit, all they wanted was to be back in Wyoming or South Carolina or Pennsylvania or wherever the hell they came from, copping a feel at a drive-in movie, sneaking a fifth with the guys, dreaming of their first car. Not slogging through a stinking tropical jungle in Chinkland, fighting off malaria, wondering if a Bouncing Betty was going to blow their balls off.