In a message dated 12/06/00 23:40:40 GMT Daylight Time, CapAAVSO@....... 
writes:

>      I have a couple of square feet of 1/32 thick mu-metal. Tell me how 
much 
>  you need to shield your seismometer's magnets and I'll cut off a piece and 
>  send it to you. It will be interesting to see what shielding it can do.

Dear Meredith,
    I use a Mu-Metal cylinder 3.5" dia by 8" long  by 0.020" thick and it 
gives a measured axial field reduction of about x30 at the centre. In the 
Earth's field, I can't measure any transverse field effect. When you bend 
Mu-Metal, the permeability does decrease a bit. 
    Regards,
    Chris Chapman
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