Chris,

Why not?  Can't you just orient them in opposite directions?  Vertical 
motions should add, while tilt accelerations will subtract.
That's what we do when we want to evaluate the magnitude of tilt-rotation 
noise on Dave's verticals.

Obviously DC tilts don't necessarily cancel, but I wouldn't expect that to 
be the primary problem.  Come to think of it, wouldn't you even be able to 
cancel steady-state tilts if you adjusted one vertical instrument slightly 
off-center in one direction and the opposing one the same amount in the 
opposite direction?

Brett

At 11:14 AM 7/25/2009 -0400, you wrote:
>In a message dated 25/07/2009, gmvoeth@........... writes:
>> > I like your Georgia Design But would absolutely need two such sensors 
>> for a complete whole.
>>
>>*** You mentioned measuring tilt that way earlier; but I don't think its 
>>that necessary.
>Hi Geoff,
>
>     You CAN'T cancel out tilt variations in vertical sensors by just 
> using two identical instruments!
>     You can do it using a seismometer AND a pure tiltmeter.
>
>     Regards,
>
>     Chris Chapman


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