I think that if you go to a basic geophysics book the sections on
gravimetery will have some formulas for the attraction of the moon and
sun as a function of latitude, year,  time of day etc.  One has to
correct for those when doing a gravity survey.   The second order
effects are harder to get and very, very small.

Absolute gravity measurements used to be made with pendulums.  I do not
know how they do them now.  I think they had to stay on station a long
time,  like longer than the variation due to sun moon interactions,
however a good geophysics or geodesy book will have that in it also.  

Tom Schmitt

-----Original Message-----
From: psn-l-request@.............. [mailto:psn-l-request@...............
On Behalf Of BOB BARNS
Sent: Friday, June 24, 2005 8:06 PM
To: psn mail
Subject: earth tide tables

Hi gang,

   A friend has several high precision pendulum clocks (and has built 2 
others).
   He asked me to inquire of this list about where to get tables of 
earth tide data so that he can compare changes in the local value of g 
to daily variations of period which he sees in his clocks.

Bob

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