Bell in Vacuum (LSE) Nature, of course, abhors a vacuum - and sound waves won't travel through one. Prove it with a ringing bell inside a sealed glass jar. As air is gradually pumped out of the jar, the bell becomes faint, then dies. Includes jar, vacuum plate with valve, rubber seal, bell system, and instructions. You need a vacuum pump and 2 AA batteries, not included. Bell may be removed for other vacuum experiments. The inside height is 8 inches, and the diameter is 8 inches. Qty :