[Phys-L] Re: fun with tides

[anngeorg at PACBELL.NET (Bernard Cleyet)]

"... the answer is most definitely yes.  It amounts to approximately one foot."

Curious.  The site:

http://pkukmweb.ukm.my/~rahim/Gravity%20method.htm
<http://pkukmweb.ukm.my/%7Erahim/Gravity%20method.htm>



claims the variation in g, as measured by a spring gravimeter, due to
the moon is not direct, but due to the increase in the distance from the
center of the earth.  So I calculated that distance using the values
9.78 m s^-2 and r = 6.37 10^6 m;  the result is ~ 65 cm.  the delta g
value I used is 0.2 mgal from the above source

bc

p.s. I did this a few weeks ago as a digression while determining the
sensitivity necessary for a pendulum to detect the lunar variation for
my horologist friend.  His published excerpt below:



"The Littlemore clock is widely regarded as the most accurate pendulum
clock ever made. But it was not perfect, and it was evidently a source
of disappointment to Professor Hall. According to Philip Woodward, as
read by Timothy Treffry at the Time Symposium in Portland this year,
Hall said "So it's curtains then" when he was informed that the analysis
of his data did not show the tidal forces as well as Boucheron's work
with Shortt clock number 41.

The two clocks are compared in the graphs below. There appears to be
much more noise in the Littlemore data and only three of the tidal
events are visible."






Michael Edmiston wrote:

> Jack Uretsky said... "Sorry.  I don't see how the bore-hole data are
> related to the question."
>
> Did you read the whole link that Brian provided?  Toward the end it
> explains exactly what is measured, how it is interpreted, and why it is
> done in a bore hole.
>
> If the question is whether or not the earth has a tidal bulge (i.e.
> tides in the lithosphere), the answer is most definitely yes.  It
> amounts to approximately one foot.  The site Brian referenced is one of
> several that describe how it is measured.
cut