Quote Originally Posted by Tinker Dwight View Post
The better way is to move a solid weight with a high
coefficient material. This is the typical iron bob with the brass nut near the
center of the bob, used on a low coefficient rod, such
as invar, fused quartz or Zerodur.

Tinker Dwight
Exactly. Reifler's pendulums worked better than any mercury pendulum ever did.