earth resonance

I have a couple questions about Tesla's work with earth 
resonance.  It seems that in his Colorado Springs work he 
somehow produced a frequency (8hz, 16hz) that resonated 
perfectly withe earths natural resonance and produced 
remarkable results.  How did he produce a wave of that 
incredibly low frequency?  Has anyone experimented with 
earth resonance?  If so, could you please forward as much 
information as possible about it.

Another question...  He also used salt water/glass 
capacitors which I've heard from several people have high 
losses.  Well if he used them and obtained the results he 
did then why is everyone moving to new age plastics.  I 
think one of the reasons that many of his ideas and 
inventions have not been replicated is that we have been 
blinded by modern day technology and techniques.

I recently made an air driven rotary gap that works better 
then my previous motor driven gap.  Plus it doubles to 
quench the spark simultaneously.  I suggest that some 
should try an air driven instead of motor driven.  I was 
able to achieve faster speeds as well.  


Chris Wezyk

[ If someone could clear up the question of earth resonance (how it was
  produced), I would appreciate it.  It would help me resolve the
  question of whether it is tesla coil related or not. -- Chip ]