AT MOST II ERIC PRESSURE. 



I 



The atmospheric pressure was observed by means of a mercurial barometer sus- 

 pended on board the schooner ; its index error, if any, is not known. The readings 

 are given in English inches, and those of the attached thermometer in degrees of 

 Fahrenheit. 



The observations here recorded commence with September 1, 1860, and extend 

 to August 1, 1861 ; the record is nearly complete for the hours 8, 10, noon, 2, 4, 

 6, 8, 10, P. M., but for midnight and the morning hours 2, 4, 6, it is defective, and 

 in April, May, and June, observations at these hours are altogether wanting. 



For the reduction of the readings to the temperature of freezing water. Table 

 XVII, C, of Guyot's Meteorological and Physical Tables (Smithsonian Miscellaneous 

 Collection) was employed. 



The approximate reduction of the readings of the barometer to the level of the 

 sea is +0.006 inches. 



( 193 ) 



26 Novombei", 1S65. 



