Warner, Deborah J. warnerd@......
Subject: History Matters



I would like to find a torsion seismograph of the sort introduced in 1950 b=
y William F. Sprengnether,=20
Jr., and sold in kit form.
=20
Deborah Warner
=20
Hi Deborah,=20
=20
    Half a minute and I will have a look in my old cellar....!=20
=20
    I typed 'torsion seismometer Sprengnether' into my search and it came u=
p with=20
quite a lot of information from St Louis University. Maybe contact them and=
 see if=20
they have one spare ? Maybe a museum ? See =20
http://www.eas.slu.edu/eqc/eqc_history/SprengnetherInstruments/eqc_SprengIn=
st.html=20
http://www.eas.slu.edu/eqc/eqc_history/SprengnetherInstruments/Sprengnether=
_SeriesAR_Seismograph.pdf=20

    It looks to me like a DIY copy of a Wood-Anderson Seismometer + a light=
=20
source and a recording drum. Maybe have a machine shop make a copy from=20
these drawings, if you want one to display? I can't believe that they were =
sold in=20
any great quantity. About as common as hen's teeth, would be my guess.=20
Amateur seismology did not really 'take off' until semiconductor operationa=
l=20
amplifiers, like the LM741, became available in the mid 1970's.
=20
    What is very interesting is the idea of using the gravitational couple =
on the=20
mass to offset the torsional couple in the wire to increase the period from=
 0.5 to=20
10 seconds. But the construction would be much better if the torsion wire w=
as=20
tensioned by a leaf spring to ~eliminate thermal expansion effects. The thi=
n wire=20
will have a thermal time constant of only a few seconds, whereas the frame =
will be=20
many minutes and the actual expansions with temperature won't match very we=
ll.=20
The torsion wire will be Tungsten.
=20
    I hope that this is of some help.
=20
    Regards,
=20
    Chris Chapman MA (Physics)







=
Warner, Deborah J. warnerd@......

Subject: History Matters











I would like to =
find a torsion seismograph of th=
e sort <=
FONT size=3D2 face=3D"Arial, Helvetica, sans-serif">introduced in 1950 by William F. Sprengnether, 


Jr., and sold in kit form.



 


Deborah Warner


 


Hi Deborah, 


 


    Half =
a minute and I will have a look in my old cellar....! 


 


    I typ=
ed 'torsion seismometer Sprengnether' into my search and it came up with 



quite a lot of informati=
on from St Louis University. Maybe contact them and see if 


they have one spare ? Ma=
ybe a museum ? See  


http=
://www.eas.slu.edu/eqc/eqc_history/SprengnetherInstruments/eqc_SprengInst.h=
tml 


http://www.eas.slu.edu/eqc/eqc_history/SprengnetherInstrument=
s/Sprengnether_SeriesAR_Seismograph.pdf 


 


    It lo=
oks to me like a DIY copy of a Wood-Anderson Seismometer + a light 


source and a recording drum. Maybe have a machine shop make a copy from 


these drawings, if you want one to display? I can't believe tha=
t they were sold in 


any great quantity. About as =
common as hen's teeth, would be my guess. 


Amateur seismology did not really 'take off' until semiconductor operational 



amplifiers, like =
the LM741, b=
ecame available in the mid 1970's.


 


    What =
is very interesting is the idea of using the gravitational couple on the 



mass to offset the torsi=
onal couple in the wire to increase the period from 0.5 to 


10 seconds. But the construct=
ion would be much better if the torsion wire was 


tensioned by a leaf spring to=
 ~eliminate thermal expansion effects. T=
he thin wire 



will have a thermal=
 time constant of only a few seconds, whereas=
 the frame will be 


many minutes and the act=
ual expansions with temperature won't match very well. 


The torsion wire will be=
 Tungsten.


 


    I hop=
e that this is of some help.


 


    Regar=
ds,


 


    Chris=
 Chapman MA (Physics)