The Vacuum/Siphon pot has been around since 1830’s and has remained almost unchanged. The pot consists of a bottom carafe, a top brew bowl, and a stem or other “plug” to help control the process.
Vacuum/siphon coffee is also an immersion process driven by vapor preasure forcing the hot water up the stem into the brew bowl. Once the water fills the brew bowl and some extra vaopr gas is released, a siphon effect draws the brewed coffee back down into the lower carafe.
Making vacuum/siphon coffee is like a science project to watch. My mother made coffee with a Cory vacuum brewer for decades.
