>
>In my experience the gravimeter is mounted on a gyro stabilised and damped 
>platform good enough that it won't spill a glass full of water in a force 
>3 sea over many hours. The gravity field features run by very slowly wrt 
>the disturbances induced by the ship or helicopter and can be filtered out 
>later via computer. At the same time another gravimeter runs at the base 
>station and records diurnal changes. When the two records are fed to the 
>computer it can figure out what the moon & tide did and remove the fast 
>noise from the movement of the instrument.

Ok, I thought it might be something like this. WAY oversampled
I saw a seismic observatory in Hawaii, that was able to see waves breaking 
on the shore (<1' waves) a couple miles away.

All in all, a fun measurement problem.

>It is not very hard to make a diy 'instrument' using bowling balls, 
>fishing line and a couple of other household implements:

This is the cavendish rig then? 

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