Unknown component

  I have a component I am trying to identify.  It consists of a glass
tube about 3/4" long and 1/8" diameter.  Inside this tube are 2 blades
that look like the might contact each other where they overlap
slightly.  There is a wire coming in from either end into the glass
tube and the ends are fused shut(melted) The only markings on the
outside are as follows:
RS 338 147
Can anyone identify what this is?

Thanks,
BV