This item is of course one of those blast monitoring instruments
recently discussed here. This particular one is an older version which
records the data on a cassette tape, designed prior to the availablility
of low-cost digital components.  I would guess that the system can play
back analog recordings and probably has an indicator of "peak-particle
velocity".  The Bureau of Mines has published a document that says
vibrations less than 2 inches/second (5 cm/sec) do not damage
structures.

Except for someone who wants to check up on their local quarry blasting,
its principal value would be in the 3-component geophone (probably 4.5
Hz) and the shipping case.

> Bryan&Regina Goss wrote:
> 
> 
> 
> Dallas Instruments ST-4 Seismograph
> 
> Item # 1450505908 I saw this on ebay used for mining.............

-- 
Doug Crice			 http://www.georadar.com
19623 Via Escuela Drive		      phone 408-867-3792
Saratoga, California  95070  USA	fax 408-867-4900
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