Does anybody know about Brindleyand Foster organs.According to my info at hand,a organ was installed in the Dutch Reform Church Bosmanstraat Pretoria S.A. in 1904.The info states that the organ had an hydraulic-pneumatic action.I've never heard of an hydraulic-pneumatic action,if any info is available please let me know.I'm interested in type of hydraulic mechanism-operating pressure,wind operating pressure and any other technical information.