4A30.46 - Trevelyan Rockers

See paragraph one in the procedure section
Code Number:
Demo Title:
Trevelyan Rockers
Expansion, Contraction, & Heat Transfer, Frequency of Sound Waves
Area of Study:
Trevelyan Rockers, Lead Blocks (Triangular), Bunsen Burner, Disposable Grill Lighter, Insulated Gloves.

Heat the large ends of the Trevelyan Rocker with the Bunsen burner for several minutes. Set it upon the lead brick with the small end of the rocker resting on a table. The rocker will start to vibrate due to the rapid expansion of the lead under the rocker. This rapid expansion causes the rocker to tip so that one edge and then the other is making close contact with the lead. One of these lead blocks is kept in the refrigerator as the greater the difference in temperature between the block and the rocker the better it works. Another interesting note is that the frequency of the rocker will not descend steadily, but will jump from one harmonic to another. NOTE: If the rocker does not start to vibrate spontaneously a gentle bump is enough to start the process.

  • Ira M. Freeman, "Department of Forgotten Lore", TPT, Vol. 12, # 6, Sept.  1974, p. 348.
  • H- 24:  Richard Manliffe Sutton, Demonstration Experiments in Physics.
  • George M. Hopkins, "Sound", Experimental Science, p. 163.
  • George M. Hopkins', "Some Effects of Large Currents", Experimental Science, Volume Two, p. 337.
  • C. L. Stong,  "On a Paradoxical Pump, Reversing Cubes, Vortex Rings, and Various Other Matters",  The Amateur Scientist,  January, 1965.
  • Jearl Walker, "Thermal Oscillators: System That Seesaw, Buzz or Howl Under the Influence of Heat", The Amateur Scientist, Feb, 1983.
  • Julius Sumner Miller, Q107 & A107, Millergrams I – Some Enchanting Questions for Enquiring Minds, p. 68 & 115.

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