Davey noticed as he played the saxophone at home that everything resonated at a different frequency.
"The glasses will tinkle on one note. Knives and forks in the drawer will tinkle on another note and I realised that everything has its point of vibration," he said. "In the same way, a component in the ball is tuned to a certain frequency."
A retired engineering professor, Arthur Williamson, was invited to look at the boiler in action. He said:
"I don't know enough about sound to know whether you can transfer that amount of energy via soundwaves. I doubt it," said Williamson.Someone, please, take it to bits. Link
He did remember an alternative kettle years ago that had two perforated metal plates inside. The power ran between the plates, through the water. "The resistance through the water provided the load. I wonder if it isn't working like that? Without taking it to bits, you can't tell."