A quartz crystal which controls an oscillator is placed in a chamber which may be evacuated. The output of the oscillator increases as the air pressure is reduced.
Proceedings of the Iowa Academy of Science
©1931 Iowa Academy of Science, Inc.
Thompson, George E.
"Effect of Air Pressure on the Vibration of Quartz Crystals,"
Proceedings of the Iowa Academy of Science, 38(1), 215-215.
Available at: https://scholarworks.uni.edu/pias/vol38/iss1/60