Greg, the Chinese "instrument" is the Seismoscope built by Chinese
scholar Chang-Heng about 132A.D. I found the discription of the Geophone
even more interesting. It reminded me of a pre WWI deveive I read about.
Here is the text description. 

Source: A.S. EVE and D.A. Keys, 1938, Applied Geophysics, Cambridge at
the University Press Page 230

Seismic Methods  "Thus geophones were used in the War, and may be used
in mines for detecting the direction of such disturbances as blasting or
the noise of a pick in tunnelling. Two geophones are employed of similar
size and construction, in each of which an iron cylinder floats on
mercury, while above the iron is a layer of enclosed air connected
through a small hole with a rubber tube leading to the observer's ear. 
One geophone is thus connected to the right ear, the other to the left.
The shock comming through the ground displaces the case of the geophone,
while the inertia of the mercury and iron tends to hold them relatively
at rest. Hence, the air is driven in rhythmic puffs through the holes
and tubes to the observer's ears, and he hears the sound in a quite
natural fashion. The remarkable physiological phenomenon of "binaural
hearing" now comes into play."


What has got my attention is that you did not describe any electrical
connections and you mentioned an iron section. Is there a coil in the
Pollard Geophone? Or could it be a orignial pre WWI geophone?

Regards, 
  

Greg wrote:
> 
> I got another email from my Geophone FAQ. Again, I can't really answer
> the question. I'd appreciate any thoughts for the reply and the FAQ. I
> asked the author to join the list, but I don't think that happened yet?
> 
> 
> I have a pair made of brass top and bottom
> plates seperated by what looks like an iron
> section. Ther are about 3 1/2" in diameter
> and 1 3/16" thick ( each section being 3/8").
> 
> They are marked "GEOPHONE Joseph G Pollard
> Co. New Hyde Park, N.Y. 1863".
> 
> My questions are :
> 
> 1. Could they really be that old?
> 
> 2. If they are, what were their uses during
> that period ?
> 
> 
> I've seen the antique Chinese "instrument" with the balls that fall out
> of the dragon mouths, but how far back does something like this go? I
> know that there have been some large earthquakes "recorded" throughout
> history, but I thought that most of the really old ones are estimated by
> damages and people's guesses.
> 
> The list has been a little quiet lately hasn't it?
> 
> As always, thanks for responses,
> Greg
> 
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