"Well, you've seen oil derricks or pictures of 'em? You know
that little platform that runs around the outside of the derrick about halfway
up? Well, that's the fourble board. Well, you see, drill pipe comes in
lengths and you handle them with several lengths screwed together so as to
save time gettin' 'em in and out of the hole. Two lengths is a double, three
is a treble, four is a fourble."