1-46. What is the normal operating accuracy of 

 the marine barograph with respect to true 

 pressure? 



1. ±0.3 mb 



2. ±0.5 mb 



3. ±0.67 mb 



4. ±0.68 mb 



1-47. You must take the following steps when 



changing the chart and winding the clock 

 of a marine barograph. What is the cor- 

 rect order of these steps? 



A. Wind the clock 



B. Place the new chart on the cylinder 



C. Set the pen to the correct time by 

 rotating the cylinder 



D. Disengage the pen from the chart and 

 remove the cylinder 



E. Carefully install the cylinder ensur- 

 ing that the anti-backlash gear teeth 

 engage 



F. Check the ink level in the pen and 

 lower the pen to the chart 



1. D,B,A,E,C,F 



2. D,A,B,E,C,F 



3. A,D,E,B,C,F 



4. A,D,B,E,C,F 



1-48. What is the cause for a trace on a marine 

 barograph chart that is weak in color? 



1. The point of the pen has become dull 

 or bent 



2. Dust has accumulated on the pen point 



3. The instrument ink has become diluted 

 by absorbing moisture 



4. The fluid in the dashpot has dropped 

 to a low level 



1-49. On what principle is the operation of the 

 Fortin mercurial barometer based? 



1. The difference in coefficients of 

 linear expansion of mercury and glass 

 causes the height of the mercury 

 column to vary with air pressure 



2. A vacuum presses down on the mercury 

 in the column with a force equal to 

 the force of air on the mercury in 

 the cistern 



3. Air presses down on the mercury in the 

 cistern with a force equal to the 

 height of the mercury column 



4. The change in the shape of a mercurial 

 cell is proportional to the change in 

 air pressure 



1-50. When is the adjusting screw of the Fortin 

 barometer utilized? 



1. After each reading of the barometer 



2. Before each observation with the 

 barometer 



3. Immediately before the barometer is 

 installed 



4. Immediately after installation of the 

 barometer 



1-51. Which of the following statements is cor- 

 rect regarding the kid leather bag of the 

 Fortin barometer? 



1. It will not prevent mercury leakage 



2. It prevents air from entering the 

 cistern area 



3. It assures that the outside air pres- 

 sure and the cistern air pressure are 

 equal 



4. It must remain in the same position to 

 be effective as a shock absorber for 

 the instrument 



1-52. The Fortin barometer can be read, without 

 interpolation, to the nearest 



1. 0.002 in. on the vernier scale 



2. 0.002 in. on the stationary scale 



3. 0.050 in. on the vernier scale 



4. 0.050 in. on the stationary scale 



1-53. What maintenance may the Aerographer 's 

 Mate perform on the Fortin barometer? 



1. Shine the scales with a high grade, 

 commerical polish 



2. Replace broken glass tubes 



3. Change damaged thermometers 



4. Replace mercury lost due to leakage 



1-54. How do reliability and convenience of 



aneroid barometers compare with reliability 

 and convenience of mercurial barometers? 



1. Aneroid barometers are less accurate 

 and more difficult to handle than 

 mercurial barometers 



2. Aneroid barometers are more accurate 

 and more difficult to handle than 

 mercurial barometers 



3. Aneroid barometers are less accurate 

 and easier to handle than mercurial 

 barometers 



4. Aneroid barometers are more accurate 

 and easier to handle than mercurial 

 barometers 



1-55. Which of the following is employed in an 

 aneroid barometer to detect variations in 

 atmospheric pressure? 



1. Alcohol 



2. An evacuated metal cell 



3. Mercury 



4. Water 



