Re: Resonant Frequency

"Original Poster: Wallace Edward Brand <webrand-at-brandlaw.dgsys-dot-com> 

It has always been my understanding that it was the steel frame of the
building that was resonating, not the ground beneath it.  Tesla was
tuning his oscillator to the resonant frequency of the building. 
Wallace Edward Brand"

	In order for the frame to resonate, it would either have to be excited
(shaken) in the middle, at a frequency such that the ends didn't have
any motion (analagous to a plucked string in  its fundamental mode), or
shaken from the bottom from a VERY STIFF source (analogous to a
tuning-fork mode).  In the latter case, if the source weren't stiff, the
Q of the system (frame plus ground attachment) would be low and there
wouldn't be much of a resonant rise.  If the ground connection were
stiff, there would be a huge amount of mass to shake.