Category X :   Installation   and  Compensation  of   Direct 
                    Reading Compass

     Knowledge  of  general  principles  of  magnetism,  magnetic 
     materials  and permanent magnets; polarity and  strength  of 
     bar  magnets, the earth as a magnet; the  magnetic  meridian 
     and its relationship to the geographic meridian.

     Knowledge  of  the general principles  of  construction  for 
     typical  Aircraft  Direct reading compasses,  including  the 
     magnet  system,  damping liquid, verge  ring  and  markings, 
     lubber  line,  grid wires, shock  absorbing  suspension  and 
     corrector box; the inspection necessary for the detection of 
     common defects that may arise in use.

     Knowledge of the procedure and points to be observed  during 
     installation of the compass in aircraft.

     Knowledge of the precautions to be observed in the choice of 
     site for, and the preparation of a "swinging base"  checking 
     the base by means of a landing compass.

     Knowledge of the compensation of compasses in the  Aircraft, 
     including  the observation of deviations,  the  calculations 
     and  adjustments necessary for corrections for  Co-efficient 
     A,  B  and  C,  the procedure  to  be  followed  after  then 
     corrections are made and the preparation of deviation  cards 
     and graphs.

     Knowledge  of  the use of landing compass for  checking  the 
     compasses in Aircraft.