I've been servicing this clock for many years and I've enjoyed helping to keep it a strong and healthy daily runner.

 It's not often that I get to stretch my wood working skills, but this task did and it was fun as well as challenging.  

broken wooden pendulum rod

 

I had a well cured blank that was far too large to suit the clock, so with some finely honed planes and numerous grades of abrasive I produced a replacement piece in the style of the original.  It's great to take the time to work in an area that is a little different than what I normally do in the shop.

 

unfinished wooden pendulum rod next to the broken one

 

A wooden pendulum rod using a lead bob is an old and time tested combination.  The materials are chosen to counter act the effects of temperature on the pendulum.  The lead bob is supported from below and thus expands and contracts above the total length of the pendulum and the rod is suspended from the top of the clock and expands and contracts vertically with temperature variations.  The wood and lead are chosen to cancel each other out.  They aren't a perfect match, but they are close and that helps keep the time keeping from slowing down or speeding up as the temperature changes lengthen and shorten the overall pendulum length.

There are many ways to try and compensate for temperature in a pendulum, but temperature compensation is only one of the factors of concern in the game of improving timekeeping.