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SOCIETY NAVAL ARCHITECTS AND MARINE ENGINEERS. 



Code VIII. — Height of barometer. 



The reading of the mercury barometer is to be corrected for index error, and reduced 

 to 0° C. and sea level. A table of corrections is given below. 



The corrected reading is coded by omitting the first figure of the barometer reading 

 in tenths of a millimeter; for example, 761.2 mm. is coded as 612. 



A table for converting hundredths of an inch to tenths of a millimeter is given below. 



Code IX. 



Air temperature is coded in two figures according to the following table : 



Code X. — Barometric tendency. 

 By the "barometric tendency at a given hour" is meant the amount by which the baro- 

 metric height has changed during the preceding three hours. It is to be expressed in mil- 

 limeters. For example, the barometric tendency at 8 a.m. could be obtained by comparing 



