45 



CHAPTER VI. PRESSURE 

 CONTENTS 



Page 



General 47 



Installation of Barometers 47 



Barometer Corrections 47 



Aneroid Barometers 47 



General 47-48 



Reading Aneroid Barometers 48 



Barographs 49 



General 49 



Reading the Barograph 49 



Barograph Charts --Form 455-12 49 



Entries on the Barograph Chart 50 



Installation of Barograph Chart 52 



Chart Entry 52 



Static Charge on Marine Barograph 53 



Three -Hour Pressure Tendency 54 



General 54 



Determination of Tendency from the Barograph 54 



Determination of Tendency from the Barometer 54 



Coding and Entries of Pressure Data on Form 615-5 54 



Barometric Pressure (PPP) 54 



Characteristic (a) 56 



Pressure Change (pp) 57 



CODE TABLES 



Code Table 8. --Symbol PPP--Corrected Barometric Pressure ... 55 



Code Table 15. --Symbol a--Barometer Change Characteristics 



in the last 3 hours 56 



Code Table 16. --Symbol pp- -Amount of Barometric Change 



in the last 3 hours 58 



