Billiard — Smoking Pipes Shape
Billiard is the most classic and probably the most popular smoking pipe shape. Unlike the most of other smoking pipes shapes billiard got it's name not for it's bowl, but for it's shank and stem. Together they look like a billiard cue, if the stem is conical. But the stem may be saddle too.
Meanwhile billiard has strict canons. And if a pipe don't respect billiard canons, usually it looks not so good for my opinion. First of all, the stem length must be equal to the stummel length (wooden part of a pipe). Secondly, the shank length must be equal to the bowl height.
Pipe bowl is almost cylindrical in classic English billiards, and more rounded in more modern billiards (almost close to an apple).
Bowl to shank angle is strictly 90° in classic billiards and more obtuse in danish variations. The shank is almost cylindrical, but billiards with conic stem usually start narrowing at the end of the shank.
Billiards often have a "waist" on the stem. I prefer to make the "waist" very noticeable. I think, it makes the pipe more elegant.
Billiard is a base of the whole family of pipe shapes. If the shank is longer and the stem is shorter, it is a liverpool. If the shank is long and oval, it is canadian. If liverpool's or canadian's stem is saddle, it is lovat or lumberman.