I'm looking to acquire a GB weight driven wall clock. In my searching I've noticed several of these clocks listed with a rod "chime" as opposed to a coil gong. Were some of these clocks offered with the rod as opposed to the gong, or is this a retrofit?
Doug, if the GB clock is fitted with a rod gong it is most likely original.
The rod gong was invented in 1898 and use protection granted in December of that year to Johann Obergfell. The patent was assigned shortly after that to Matthias Baüerle and rapidly commercialized with excellent acceptance by the industry. That was because the rod gong can be made to give a much richer sound than a coil gong and is less expensive to produce.
The first GB clocks with rod gongs were made in Braunau starting in 1899. By 1902 almost all Braunau clocks were fitted with rod gongs and that continued in practice until 1926 when production was stopped at that location.
In Freiburg the first clock documented with a rod gong was made in 1900, however the majority of Freiburg clocks (except for Westminster chime clocks which used 100% rod gongs) continued to use coil gongs right up to the end of production in Freiburg at the end of 1932.