http://rurmonas.cust.nearlyfreespeech.net/manuals/westonIII/westonIII.html
 
 That's the Weston III. I think the only real difference is the II used
Weston and not ASA ratings.

      Basically
     
      1) Set your film speed.
     
      2) measure the light [if it's dim light open the low light door on
the underside of the meter. Keep it closed if it's bright]

      3) Transfer the reading to meter dial
     
      4) Read it off.
     
      Of course compensate like any other reflected meter.
     
      Nick