PSN-L Email List Message

Subject: Re: Historical stuff
From: ChrisAtUpw@.......
Date: Sat, 15 Mar 2003 19:49:19 EST


In a message dated 15/03/03, dyouden@......... writes:

> 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 
> 

       ?
 
> 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 
> 

       Good idea.

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

       That is not my interpretation of Stong's text - see below.
 
> Well, there you have it. We could call the thing:
> 
> 

       Watt developed steam engines and linkages for them. He had nothing to 
do with pendulums or with seismometers.

> 

       von Kamm? There is no-one of that name at UWA and Woo gives one 
reference to a F J van Kann. There is Frank van Kann Senior Lecturer, School 
of Physics, Email: frank@..................

       Maybe he independantly invented this construction? Woo's reference is 
' (1993) - to be published' and that was in 1998. 

> 

       They did not invent it and the credit is usually given to the inventor.

> 4) Anything else anyone can think up

       Nils Lindenblad was initially trying to invent a better seismometer. 
He mentions ordinary pendulum and hanging gate seismometers. Some ignoramus 
told him that most of the 'problems' of seismometers had been solved and 
there was just some tinkering with electronics to be done. Apparently Nils 
believed this 'informant'. However, Nils describes the principles and 
construction of a normal and inverted pendulum pair which can be adjusted to 
give a theoretically infinite period. Quote "Scaling down my ambitions 
somewhat, I set out to develop a small mechanical pendulum of good quality 
and long period that could be used as a reference mass: a mass that tends to 
stand still when neighboring objects move".
       I have no evidence of any prior description to this type of pendulum 
and specifically for this use. 
       
       Regards,

       Chris Chapman
In a message dated 15/03/=
03, dyouden@......... writes:


I have, as promised, done a= little digging into the history of the folded=20
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=20= freshman studying mechanisms. I E-mailed Professor David Blair at The Univer= sity of Western Australia, where the device used by Lai Mun Woo was built. P= rofessor Blair believes that they were the first to use the mechanism for se= ismographic purposes, and he states that a senior lecturer there by the name= of F. V. von Kamm was the first to suggest the application.


      ?
=20
von Kamm was supposed to pu= blish a paper on the seismograph back in 1993,=20
but I cannot find any evidence that he did. I will try to contact him ne= xt week to find out what happened.


      Good idea.

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


      That is not my interpretation of St= ong's text - see below.
=20
Well, there you have it. We= could call the thing:

1) Watt Seismograph


      Watt developed steam engines and li= nkages for them. He had nothing to do with pendulums or with seismometers.

2) von Kamm Seismograph

      von Kamm? There is no-one of that n= ame at UWA and Woo gives one reference to a F J van Kann. There is Frank van Kann Senior Lecturer, School of Physics, Email: frank@..................

      Maybe he independantly invented thi= s construction? Woo's reference is ' (1993) - to be published' and that was=20= in 1998.=20

3) UWA Seismograph

      They did not invent it and the cred= it is usually given to the inventor.

4) Anything else anyone can= think up


      Nils Lindenblad was initially tryin= g to invent a better seismometer. He mentions ordinary pendulum and hanging=20= gate seismometers. Some ignoramus told him that most of the 'problems' of se= ismometers had been solved and there was just some tinkering with electronic= s to be done. Apparently Nils believed this 'informant'. However, Nils descr= ibes the principles and construction of a normal and inverted pendulum pair=20= which can be adjusted to give a theoretically infinite period. Quote "Scalin= g down my ambitions somewhat, I set out to develop a small mechanical pendul= um of good quality and long period that could be used as a reference mass: a= mass that tends to stand still when neighboring objects move".
      I have no evidence of any prior des= cription to this type of pendulum and specifically for this use.=20
      
      Regards,

      Chris Chapman

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