Hi,
 
 The subject of springs constantly pops up. It might be of interest to  
look at the spring from the base of an old angle poise lamp. This is in fact a  
negative length spring for small loads; the intersect passes though zero to 
 become a positive length as the load increases. It is possible to adjust a 
 seismometer fitted with such a spring to give a period of 15  seconds but 
it will not remain in this state for long.  As in all  springs the elastic 
stain is slowly replaced by creep strain. In  general the mechanism of creep 
is divided into dislocation and diffusion  creep both of which are 
temperature dependent . Dislocation creep is usually at  a max for a new spring and 
hence the use of an old angle poise lamp spring. 
 
Regards Martin





Hi,
 
 The subject of springs constantly pops up. It might be of inter=
est to=20
look at the spring from the base of an old angle poise lamp. This is in fa=
ct a=20
negative length spring for small loads; the intersect passes though=
 zero to=20
become a positive length as the load increases. It is possible to adjust=
 a=20
seismometer fitted with such a spring to give a period of 15=20
seconds but it will not remain in this state for long.  As=
 in all=20
springs the elastic stain is slowly replaced by creep strain. In=20
general the mechanism of creep is divided into dislocation and diffus=
ion=20
creep both of which are temperature dependent . Dislocation creep is usual=
ly at=20
a max for a new spring and hence the use of an old angle poise lamp spring=
..=20

 
Regards Martin