Sect. X.J 



AND BAR03IETRIC CURVES. 





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may be given by tbe curve representing the observations 



too much attention cannot be bestowed on the barometer, 

 the wet and dry bulb thermometer, the direction and force 

 of the wind, the state of the sky, and the appearance of the 

 ocean during the ship's passage through such an accumu- 

 lation of pressure. When the barometer attains its mean 

 altitude, and is rapidly rising above it in any locality, 

 then hourly observations of the instruments and pheno- 

 mena above noticed should be commenced and continued 

 until after the mercury had attained its highest point and 

 had sunk again to its mean state. In such observations 

 particular attention should be paid to the direction and 

 force of the wind preceding the barometric maximum 

 and the same phenomena succeeding it, and particular 

 notice should be taken of the time when, and amount of 

 any change either in the direction or force of the wind. 

 It is by such observations as these, carried on with great 



care and made at every accessible portion of the oceanic 

 surface, that we may be able to ascertain the continuity 

 of these atmospheric waves, to determine somewhat re- 

 specting their length, to show the character of their con- 

 nection with the rotatory storm, and to deduce the direction 

 and rate of their progress. 



Seasons for extra Observations. 



In reference to certain desiderata that have presented 

 themselves in the course of my rpsearches on this subject 

 (see Report of the British Association for the Advance- 

 ment of Science, 1846, p. 163), the phases of the larger 

 barometric undulations, and the types of .the various 

 reasons of the year, demand particular attention and call 



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