Vibration densitometer

A vibration densitometer comprising:

• an electromechanical oscillator including a probe and a feedback circuit connected in a loop;
• a function generator connected from said feedback circuit;
• and utilization means connected from said function generator, said probe including inner and outer concentric cylinders fixed relative to each other, said outer cylinder having a hole extending radially therethrough, a shaft slidable through said hole in engagement with said inner cylinder, and means to vibrate said shaft in the direction of its axis to cause vibration of said inner cylinder, said outer cylinder being completely hollow except for said inner cylinder positioned therein, said inner cylinder being hollow completely therethrough.