I have noticed that when my Lehman has its pivot against
the basement wall (with the pendulum sticking out into the
basement), this seems to minimize the noise from activity
in the house.  When I tried it in the middle of the floor,
I could see (it seemed) a squirrel jumping on the roof.  I
finally realized that this was because I had placed the left
foot of the Lehman directly next to a support column, which
was translating load changes on the first and second floor
into tilt noise.

When seismo is placed in the middle of the wall with the
sensitive axis along the wall, the wall will move up and down
with load changes,but there is relatively little translation into
tilt sue to symmetry.

Jack Ivey
KB8SPI

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