PIRA Classification: 2C20.75
Description: The hollow barrel of a pen is placed on the lecture bench. The barrel is pinched against the table with the thumbs. When the barrel snaps out from under your thumbs, it leaves the table and follows a loop-the-loop path.
Special Instructions: This is tough. PRACTICE. A somewhat easier and larger-scale demo 2C20.70 - Bjerknes' Tube is recommended instead.
Condition: Ok.
Setup time: 1 minute.
Safety Issues: None.