PSN-L Email List Message

Subject: Historical stuff
From: "David H. Youden" dyouden@.........
Date: Sat, 15 Mar 2003 07:39:11 -0500


I have, as promised, done a little digging into the history of the folded 
pendulum as a seismometer and here is what I found:

As Nils Lindenblad stated, it is a Watt's linkage, and is well known to 
freshman studying mechanisms. I E-mailed Professor David Blair at The 
University of Western Australia, where the device used by Lai Mun Woo was 
built. Professor Blair believes that they were the first to use the 
mechanism for seismographic purposes, and he states that a senior lecturer 
there by the name of F. V. von Kamm was the first to suggest the 
application. He goes on to note that the efforts at UWA have moved on to 
Roberts Linkages and Scott- Russel linkages for their applications in 
vibration isolation. Excellent papers on both applications can be found by 
"Googlizing" the linkage names.

von Kamm was supposed to publish a paper on the seismograph back in 1993, 
but I cannot find any evidence that he did. I will try to contact him next 
week to find out what happened.

Professor Blair notes that a group in Wuhan, China has built a copy of the 
folded pendulum instrument.

Note that Lindenblad specifically states that he did not build his 
pendulums for seismographic purposes, as he was trying to avoid that field 
of endeavor.

While web surfing, I happened across a site that I'm sure everyone else 
knows about. It contains an extensive history of seismographs. Here's the 

Well, there you have it. We could call the thing:

1) Watt Seismograph
2) von Kamm Seismograph
3) UWA Seismograph
4) Anything else anyone can think up


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