The Savart wheel is an acoustical device that was created by French physicist Felix Savart (1791-1841), which he used for research on lower frequency limits on hearing.
The device consists of a mounted metal disk having a large number of teeth with uniform spacings on its circumference. When the toothed disk is spun in rapid revolution, and an edge of a playing card is held against the teeth, it produces a shrill tone. When the speed of the wheel slows down, the shrill tone correspondingly diminishes in pitch. Thus, the frequency in tone is directly proportional to the rotation rate of the disk.
That was scientific principle Mr. Sullivan, our eleventh grade Physics teacher, was trying to demonstrate, using the Savart wheel as a “visual aid.”
It was an electric wheel, the disk, maybe, six inches in diameter. You plugged the wheel in to make the disk rotate. And there was a switch on it, for adjusting the speed. Mr. Sullivan used, not a playing card, but a rectangular piece of “shirt cardboard” – we called it shirt cardboard, because it served as the backing for shirts, when they came back from the dry cleaners.
After turning it on, Mr. Sullivan inserted the piece of cardboard between the teeth of the rapidly spinning disk, immediately generating a high-pitched shrill tone. He then extracted the cardboard, adjusted the wheel so the disk would spin faster, then reinserted the cardboard, causing the shrill tone to return, but this time, in a noticeably higher pitch.
Conclusion – See: Above.
It was now time for Mr. Sullivan to choose a student to duplicate the experiment. I don’t know why that was necessary. We had all had it with shrill tones, and were eagerly ready to move on.
But somehow, Mr. Sullivan deemed it to be an important element in our education. Perhaps he wanted to show how “scientific” the experiment was. The “scientific method” requires multiple repetitions of the same experiment, yielding the same result every time. That’s science. That’s how it works.
You let go of the apple, and it falls down every time. That’s gravity. “Gravity” is proven science, because the apple always falls down. The apple falls up one time? It’s back to the drawing board. And no place in the scientific pantheon for you.
Mr. Sullivan wanted to show us, not just the relationship between speed and tone frequency, but that on every occasion, when you insert cardboard between the teeth of a rotating disk, and then increase the speed, what results is a higher, though equally irritating, shrill tone.
Science is repetition yielding the same result. And you don’t have to be a highly trained high school Physics teacher to achieve it. That same predictable result could be produced by any idiot in the world.
Mr. Sullivan chose me to duplicate the experiment.
I went up to the front of the classroom. Mr. Sullivan handed me a piece of grayish cardboard. He switched on the Savart wheel. He then nodded to me to insert the cardboard between the teeth of the now spinning disk.
I behaved as instructed, imitating precisely the move I had seen Mr. Sullivan make just moments before. My efforts immediately produced the shrill tone. However, unlike with Mr. Sullivan’s demonstration, the moment I inserted the cardboard, the disk’s teeth started chewing it up, and shredding it to pieces.
I stood there, looking genuinely confused, as miniscule flakes of decimated cardboard came flying off the wheel. It was like a cardboard snowstorm. My classmates were in hysterics. Mr. Sullivan was biting his lip. The only person not laughing was me.
I had no idea what I’d done wrong. Other than not immediately extracting the shirt cardboard when it started to snow. I kept holding it between the teeth, till there was nothing left to shred. I guess I was in shock.
I had generated a cardboard blizzard in my eleventh grade classroom. And the perplexing thing was, I did exactly what Mr. Sullivan had done – I had inserted the cardboard between the teeth of the disk
What was the difference between the two demonstrations, or, more specifically, the two demonstrators?
The only thing I could think of was that Mr. Sullivan wasn’t naturally funny.