# NavList:

## A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

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Re: Equinox, eggs and other questions
From: Aubrey O?Callaghan
Date: 2002 Mar 17, 10:40 -0400

```George,
Theoretically it is correct. If on takes creeps into the Science museum in
London one night, borrows Foucault's pendulum and takes it to Kilimanjaro,
then if one is on one side of the equator one will see it "apparently"
rotating in one direction, and on the other side of the equator in the
other direction. However, if my applied mathematics is not completely
forgotten the rate of rotation is a fn. of the cos of latitude. At the
North pole (true North) then it will rotate at the same rate as the earth,
circa. once every 24 hours, at the equator the rotation will be 0. But a
little N or S it will rotate very very very slowly cos (< 1deg).

Writing this also brings to mind my applied maths class in university in
Ireland we had derived the soln. and we found Foucault's pendulum rotated
fastest at the equator. As I had spent a little time in Zimbabwe (then
Rhodesia) I knew that the Foucault pendulum they had in the University
never appeared to significantly rotate... we went thru the calcs. again and
found our error !

Wishing all a very Green St. Patricks Day !

Aubrey.

At 13:13 16/03/02, you wrote:
>  Rob Gendreau writes-
>
> >Tradition has it that at the moment of the
> >equinox you can stand an egg on end. Not to raise the specter of
> >scientific rationalism vs. folklore, but big bets are riding on this in
> >my office. Video evidence is being demanded. So an accurate time for the
> >equinox is essential.
>
>=========================
>
>Such beliefs persist.
>
>An ex-colleague was in Africa to climb Mount Kilimanjaro, and was in some
>sort of tourist-trap placed precisely on the equator. He witnessed a
>demonstration, using a bowlful of water with an exit spout at its centre.
>At one end of the compound, when the plug was pulled, the water ran out
>with a clockwise swirl. Taken to the other end, the swirl was
>anticlockwise. My colleague, a physicist of long standing, was gullible
>enough to accept that this was the result of the rotation of the Earth, and
>being on opposite sides of the equator. Some people will believe
>anything...
>
>If it had been true, however, it could have provided a novel
>aid-to-navigation, for anyone wishing to travel East-West along the
>equator..
>
>egg-on-end instant could have been used to check a chronometer.
>
>What a pity that these beliefs fail.
>
>George Huxtable.
>
>------------------------------
>
>george---.u-net.com
>George Huxtable, 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
>Tel. 01865 820222 or (int.) +44 1865 820222.
>------------------------------

```
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