All

On a recent visit to the UK I spent a day in the Science Museum in =
London, Just before I left I came across a working seismograph. It was =
completely enclosed but with only glass on two sides. There was a couple =
of  interesting things about it, first, the  boom/arm was at waist =
height which meant that instead of a large drum the paper passed around =
a smaller drum of say 23cm (~9") dia by 45cm (18") long down to a =
smaller drive roller at floor level, giving a paper belt of about 150cm =
(5'). The inking device appeared to be a capillary tube that started =
horizontally, looped upwards and come down vertically to the paper =
drawing a very fine line. Starting from the centre of the paper was =
another stylus which appeared to be recording the time. The whole paper =
belt would appear to move laterally for half the paper with. The other =
interesting point was the way the mass was used, this was hung about =
half way along the arm, I say hung as it was about 30cm (12") below the =
arm and consisted of a number of disks about 23cm (9") dia and 2cm =
(.75") thick. There was also a complicated mechanism between the end of =
the arm and the stylus, time did not allow me time to work out what did =
but it obviously had a use.

The question I ask is why hang the mass half way along and below the =
beam? Is it to magnify the amount the weight apparently moves???

Any answers - somebody must know...


Ted=20


      









All
 
On a recent visit to the UK I spent a =
day in the=20
Science Museum in London, Just before I left I came across a working=20
seismograph. It was completely enclosed but with only glass on two =
sides. There=20
was a couple of  interesting things about it, first, the =
 boom/arm was=20
at waist height which meant that instead of a large drum the paper =
passed around=20
a smaller drum of say 23cm (~9") dia by 45cm (18") long down to a =
smaller drive=20
roller at floor level, giving a paper belt of about 150cm (5'). The =
inking=20
device appeared to be a capillary tube that started horizontally, looped =
upwards=20
and come down vertically to the paper drawing a very fine line. Starting =
from=20
the centre of the paper was another stylus which appeared to be =
recording the=20
time. The whole paper belt would appear to move laterally for half the =
paper=20
with. The other interesting point was the way the mass was used, this =
was hung=20
about half way along the arm, I say hung as it was about 30cm (12") =
below the=20
arm and consisted of a number of disks about 23cm (9") dia and 2cm =
(.75") thick.=20
There was also a complicated mechanism between the end of the arm and =
the=20
stylus, time did not allow me time to work out what did but it obviously =
had a=20
use.
 
The question I ask is why hang the mass =
half way=20
along and below the beam? Is it to magnify the amount the weight =
apparently=20
moves???
 
Any answers - somebody must =
know...
 
 
Ted 
 
 
      <tedr@..................>