Chris
   I  believe that it can be proven theoretically, and i have
demonstrated empirically ,that an increase of convexity at the pivot
point can result in increased sensitivity. This makes sense because there
is less surface contact between the static and the mobile elements of the
interface . ,resulting in less friction and increased isolation of the
pendulum. My instruments and those that i modified using my technology,
have shown remarkable improvement over their Lehman counterparts. 
   I am the person who came up with the ball bearing pivot point as a
modification to the Lehman detector. The Lehman detector  using the ball
bearing pivot point  on a polished bolt head will usually perform
consistently and be stable at about 16 seconds. About a year ago i
decided to use the ball bearing for the upper pivot point also. I then
decided to use a convex static surface for the upper and lower ball
bearings to rest on. I usually run four or five detectors and chart
recorders full time. The performance of each can be compared to the
others . The quad convex surface method produced outstanding results. The
modified Lehman detector using this method can be run at about 35 seconds
or more and still be stable. 
      To work properly , the static part of the pivot point must be
constructed of a material equally hard as the ball bearing. In my
instruments it is made of another bigger ball bearing  after it has been
cut and polished. This surface should look like a mirror. 
      Will the ball bearing come off of the static convex surface while
in use? NEVER. 
      How does the ball bearing method compare to the other methods ? I
dare you to try it. BE ready for one hell of a surprise.
      


                                                                         
                                                                         
W5AUH , John C Cole




________________________________________________________________
GET INTERNET ACCESS FROM JUNO!
Juno offers FREE or PREMIUM Internet access for less!
Join Juno today!  For your FREE software, visit:
http://dl.www.juno.com/get/tagj.
__________________________________________________________

Public Seismic Network Mailing List (PSN-L)