Nice link on the tiltmeter!  I will try to get through the French later.

 

 

 

Tom Schmitt

 

-----Original Message-----
From: psn-l-request@.............. [mailto:psn-l-request@...............
On Behalf Of ChrisAtUpw@.......
Sent: Sunday, June 26, 2005 10:49 PM
To: psn-l@..............
Subject: Re: earth tide tables

 

In a message dated 26/06/2005, tschmitt@.............. writes:

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.

    There is quite a bit of information on gravimeters at
http://www.ecgs.lu/ The Earth tides give angular changes of about 50 to
100 nano radians. 

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.  

    The geo survey type used twin pendulums of fused quartz and optical
readout. I have given a few more references at
http://www.seismicnet.com/psnlist/030520_101305_1.html

 

    Earth tides are more easily measured using large water tiltmeters.
Nicolas d'Oreye's Thesis using measurements at Walferdange is on line at
http://edoc.bib.ucl.ac.be:81/ETD-db/collection/available/BelnUcetd-10172
003-155611/ It is listed as a series of chapters. If your French is a
bit rusty, you might want to access the sections using babelfish
http://babelfish.altavista.com/

 

    Regards,

 

    Chris Chapman


















Nice link on the =
tiltmeter! 
I will try to get through the French later.

 

 

 

Tom Schmitt

 

-----Original =
Message-----

From: =
psn-l-request@..............
[mailto:psn-l-request@............... On
Behalf Of ChrisAtUpw@.......

Sent: Sunday, June 26, =
2005 10:49
PM

To: =
psn-l@..............

Subject: Re: earth tide =
tables

 



In a
message dated 26/06/2005, tschmitt@.............. =
writes:





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.





  &nbs=
p; There
is quite a bit of information on gravimeters at http://www.ecgs.lu/ The
Earth tides give angular changes of about 50 to 100 nano radians. =






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.  





  &nbs=
p; The
geo survey type used twin pendulums of fused quartz and optical readout. =
I have
given a few more references at http://ww=
w.seismicnet.com/psnlist/030520_101305_1.html





 






  &nbs=
p; Earth
tides are more easily measured using large water tiltmeters. Nicolas =
d'Oreye's
Thesis using measurements at Walferdange is on line at http://edoc.bib.ucl.ac.be:81/ETD-db/collection/availa=
ble/BelnUcetd-10172003-155611/ It
is listed as a series of chapters. If your French is a bit rusty, you =
might
want to access the sections using babelfish http://babelfish.altavista.com/<=
/a>






 






  &nbs=
p; Regards,





 






  &nbs=
p; Chris
Chapman