The first post was for a compound pendulum. That is the correcxt name.
Kater's pendulum is quite different
Alex. F. Burr
In a message dated 12/3/2010 8:59:23 P.M. Mountain Standard Time,
vwlsps@rit.edu writes:
I believe you are referring to Kater's Pendulum. Check out Wikipedia or
google it to confirm. If so, there are two pivot points that have the
identical period.