Instructions for the Galilee Work 



Scheme B. — Other Helm: Deflections with Sea Di-p-Cirde} 



121 



'Needle 4 will be placed inside aluminum case so as to bring letters .4, B toward obser\'er for short distance, and away 

 from observer for long distance, and is not to be touched thereafter for the entire swing. Face of needle 3, throughout swing 

 will be toward observer for short distance, and away from observer for long distance. 



Scheme D. — Other Helm: Deflections with Sea Deflector, again using Magnet iS. 



4. Horizontal-intensity observations with sea deflector 1 (Dl). — Schemes C and D will be 

 followed. Care is to be taken in the temperature readings, end of block containing deflecting magnet 

 being protected against air currents. Magnet NL will not be used for these swings, solely magnet 

 45. (Directions regarding use of magnet NL will be supplied later.) 



5. Should it be found feasible, there will be no objection against securing declination determina- 

 tions during the swing by the person at the Ritchie standard compass (RIB); this matter must be 

 left to the commander's judgment. The method outlined in schemes C and D will again afford data 

 for determining the deviations of the Negus compass (Dl) without making azimuth observations. 



6. The Kelvin compass will of course not be moimted on its biimacle throughout these swings; 

 this compass is to be used only for certain experimental work at sea. 



