Spill Proof Bong. Patent number: 4241741 Issue date: Dec 30, 1980

“However, there are several problems with the design of the traditional basic bong. The first is the seepage of the bilge in the bottom of the bong barrel up through the stem into the tobacco bowl, thus rendering the tobacco difficult to burn. Another problem resides in the vulnerability of the open-topped bong to spillage when knocked over and the incumbent mess created in the interior of the user’s home.”