CONTENTS 



Page 



An appreciation vi 



I. The ocean weather service 1 



II. General information for the marine observer 2 



Arrangements for reporting 2 



Instruments 3 



Forwarding reports by mail 3 



Pilot charts 3 



"Weather on the Oceans" 4 



Location of Weather Bureau offices 4 



Condensed instructions for taking and recording observations 



(French, German, Italian, Dutch, and Japanese) 4 



III. Instruments and instrumental observations 9 



Mercurial barometers 9 



Mercurial barometers of marine type 9 



Explanation of scale of marine barometer 11 



Errors of mercurial barometers 11 



Location of the mercurial barometer 12 



The principle of the vernier and the method of reading it-- 13 



Correction and reduction of barometer readings 15 



Aneroid barometers 16 



Effects of temperature 17 



Aneroid barographs 17 



Reading of aneroid barometers 18 



Defects in aneroids 18 



Compensation for temperature 19 



Measures for remedying defects 20 



Testing of aneroids 20 



Replacement of defective aneroids 21 



Barometer comparisons 22 



Lack of agreement in the observations 23 



Frequency of comparisons 23 



Change in barometers 24 



Thermometers 24 



Use of thermometers in meteorological observations 24 



Exposure of thermometers 25 



The aspiration thermometer 26 



Psychrometers 26 



The sling psychrometer 27 



Bucket and intake methods of obtaining ocean surface temper- 

 atures 29 



IV. Instructions for taking and recording weather observations 30 



Notes on instruments used 31 



Time and position 32 



Day of month 32 



Local ship's time 32 



Day of week 32 



Octant of globe 33 



Latitude and longitude 33 



Greenwich civil time 34 



Wind 34 



Wind direction 34 



Wind force - — 35 



The apparent and the true direction and force of the wind- 37 



Weather 38 



Explanatory remarks on the code table for "present 



weather' ' and instructions for itsuse 41 



III 



