Independents

Jack Forster
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Two points in rebuttal. . .

. . .firstly, I find it difficult to imagine what acoustic coupling might be occurring in the Journe watch, if by acoustic coupling I understand you to mean sound waves causing one balance to resonate with the other. The rotations of the two balance wheels don't seem to offer much in the way of sound energy, and furthermore IIRC the specs for the watch call for the two balances to be extremely close to each other, which would tend to argue for aerodynamic drag rather than sound per se.

The fact that two oscillators are mechanically coupled doesn't, as far as I understand it, mean that resonance is not occuring. In your example of the wheels of a watch vs. the two balances in the Haldimann watch, of course the train wheels are not oscillators . Mechanically coupled resonance is a perfectly valid term as far as I can see; in fact, in pendulum resonator clocks the pendulums are coupled mechanically by the movements, which was the basis of Huygen's original observation of resonating pendulums. An excellent precis of the mechanical coupling of pendulums can be found in this article from Antiquorum:]

http://www.antiquorum.com/html/vox/vox2004/tiffany.htm

In a pendulum clock, there are two weights swinging in opposite directions, loading the frame with a lateral force at the limit of the swing. In a watch with a balance, on the other hand, the rotation of the balance wheel itself produces as far as I can see, virtually no lateral loads to transfer to the plate; the only loading of the movement with mechanical energy by the oscillators (which are what have to be interacting for it to be true resonance) is at the attachment of the hairspring to the stud, and I'd be willing to go out on a limb and say that those forces alone are not adequate to cause resonance to occur.

I don't think that it's impossible that the Journe watch is a demonstration of true resonance but to fit the definition, resonance should occur by the transmission of energy from one balance to the other, even in the absence of power going to one of the balances. It would be an easy test to do. Also please note: the balances as I understand it in the Journe are rotating in such a way as to produce drag on each other, and this may reduce balance amplitude as well. Once again, the test is easy: shift the balances away from each other and measure the amplitude when they're uncoupled, and then shift them towards each other and measure the amplitude. If the amplitude is decreased by the coupling of the two movements this would, it seems to me, tend to indicate that they're damping each other rather than resonating with each other.

Actually, one could just take two watches, both with the same number of VPH, and wind one up but not the other, and then put them in contact with each other and see what happens. Hmm, guess what I'm doing tonight.

Jack

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