"Walt Davidson" wrote in message
...
On Sun, 12 Oct 2003 12:03:10 +0100, "Brian Reay"
wrote:

tourbillion: a mechanism to prevent changes in local gravity (due to
movement) from changing the period of oscillation. Not generally required
in
a stationary clock and, even in watches, usually avoided by setting an
average rate in six positions.

When I worked at the Science Museum in the mid 1960s, one of my duties
was to start the Foucault Pendulum at 2 pm on a Sunday afternoon. Its
purpose was to demonstrate and measure the effect of the earth's
rotation on the direction of swing of the pendulum.


It is funny how these things 'come around'.

I learned about "tourbillions" and the like as a hobby / pastime while
studying for my first degree and due to an interest in 'nice' watches (Rolex
et al) I never expected it to be useful in the 'real world'. However,
similar issues came along when working on gyro based navigation systems-
finding ways to compensate for "g terms" and "g^2 terms" in gyro drift
models, using maths and calibration procedures ( some systems rotate the
gyros on a tourbillion like mechanism but these defeat one of the objects
of a 'strapdown' system).

I never expected to use it again and along comes Gareth with his spade ;-)

73

Brian