Info wanted on original Clarostat 240 Power Decade Resistance

[HalFoster]

I have an original Clarostat 240 Power Decade Resistance box - just model "240", not the "-B" or "-C" revision.  It has the dials going from LSD to MSD, opposite of the later versions, serial number 1368 and am curious if anyone has any further information on this model.  I can't locate anything other than the -C model - even in catalogs and am curious as to when this was first introduced.  Really, any old Clarostat catalogs would be very interesting.

Thanks!