Re: New Madrid helicorders
Posted by Roger Hunter on September 20, 2005 at 10:00:51:

Ara;

No, a Helicorder (helical recorder) is a recording device for seismometers which uses a strip of black paper covered with white wax wrapped around a cylinder. A hot pen melts the wax as the drum turns, making a black line. The pen slowly moves across the drum so the line is a spiral.

When the paper is removed you see a series of lines depicting the signals.

Roger


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     ● Re: New Madrid helicorders - Ara  22:40:46 - 9/20/2005  (28440)  (0)