The Science & Technology Concentrate, “Scans expose violins’ density differences,” was great (C&EN, July 14, page 34). I would love to hear Jascha Heifetz play his Stradivarius.
A 1981 episode of “NOVA” called “The Great Violin Mystery” was about a Wisconsin physicist named William F. Fry who had figured out the “secrets” to these violins.
As I recall, he discovered that even two pieces of wood cut to the nearest ten-thousandth of an inch vibrate harmonically at different frequencies. The show illustrated two such pieces of wood in tools that ran the spectrum of vibration. I never realized that the woody part of the violin is just an amplifier for the strings.
The masters carved the hourglass-shaped back of the violin. The note of different tuning forks was amplified at different places, as it was run across the back of a violin. This is where we have not yet, to my knowledge, remastered the craft—carving the back so that each unique piece of wood will amplify the range of notes. Fry theorized that the masters carved the wood to make a series of hourglass-shaped lines of exactly the same thickness or to yield the same harmonic amplification moving from a thin center to a thicker edge.
The back was precisely carved to amplify the lower notes of the violin. The wood between the “F” holes was for the middle and high tones, and the bridge acted as a filter.
The sounding post connects the top to the bottom and it is off-center. The presenter demonstrated this phenomenon by jumping on a rectangular trampoline with some of the springs removed. The sweet spot shifted off center.
The presenter even verified his theory using a nondestructive technique that measured the thickness of the back of a real Stradivarius. I recall that its owner was extremely nervous about having anyone touch his violin.
It’s my studied opinion that the frequent focus on varnish is nearly irrelevant compared with the amplification part of the equation. Surely, the varnish could damp out some bad vibrations, but that is fine-tuning.
This concept should be easy for chemists to grasp, as we spend a lot of time studying harmonic orbitals of electrons, although this appears to be a continuous, rather than a discrete, phenomenon.