Steve Hammond wrote:

> 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

Neat. I wonder if anyone ever got mercury in their ears?

> 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?

The description doesn't sound too far off. What I qouted is all that I
have right now. I asked for more information. When/if I get it I'll
forward that to the list also.

Thanks for looking into it,
Greg

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