(under subclass 196) Smoking devices having a plurality of smoke passages connected, in series, arranged to extend in substantially opposite directions, so that the smoke reverses its direction of travel. This is generally stated to be for providing an elongated smoke passage to give the smoke time to cool and/or to cause precipitation of suspended solids or liquids due to their inertia when the direction of motion of the smoke changes.
(1) Note. Compare this class, subclasses 212.1+, 213 and 218.
