The Charatan Underboar system description
During a period from 1920s to WWII Charatan proposed pipes equipped with a self-cleaning system. Description and operating information of what looks like a gimmick are summerized below in a descriptive boocklet issued by the londoner maker.
The model was marketed in the US by Samuel Gordon. That's why the pipe is often referred to as the Gordon Underboar in America. In this case the US distributor made the pipes stamped with his name.
Booklet by Charatan
Click to enlarge
October 23, 1924.
Ad in Princeton's newspaper offering the Underboar to the college crowd, available at Skirm's Smoke Shop
1932.
The Times of India Annual.
Click to enlarge