106 RECORD AND DISCUSSION OF ATMOSPHERIC PRESSURE. 



NOTES TO PRECEDING ABSTRACTS. 



September, 1853. During the whole month, the readings were taken from the aneroid barometer. 

 They were converted by means of a table to the corresponding readings of the mercurial 

 barometer. 



llth. The dates before the llth, were changed from nautical into civil reckoning. 

 14th. At 3 P. M., the aneroid barometer was removed from the cabin to the deck ; a change of six 



feet of greater elevation. 

 19th. At 9 A. M., the barometer was brought from deck to cabin (six feet lower). During the 



hours 7 and 8 A. M., it became colder than the scale could register. 

 14th-19th. A correction of + 0.006 inch has been applied to the barometer readings, to refer them 



to the level of the cabin. 

 October, 1853. 24th. From this day, the readings of the mercurial barometer are given. The position 



was in house on deck. 



25th. Readings at 1, 2, 3, and 4 P. M., supplied from the aneroid in cabin. 

 January, 1854. 23d. The star prefixed to the hours between 9 A. M. and midnight, indicates that the 



decimals belong to 28 inches. 



24th and 25th. The star indicates 28 inches as above. 

 February, 1854. 18th and 19th. The star in the place of the units indicates that the decimals belong 



to 28 inches. 

 June, 1854. 22d and 23d. The deck house was removed; the mercurial barometer, however, remained 



on deck. 



July, 1854. 31st. Between 1 A. M. and 2 P. M., the readings of the aneroid appear to have been inad 

 vertently inserted in the column for the mercurial barometer. In the abstract the readings 

 were accordingly exchanged. 



August, 1854. 27th. The readings of the two barometers between the hours 5 A. M. and 12 P. M. 

 appear to have been accidentally exchanged, as indicated by the temperature readings. After 

 9 A. M. the aneroid was read, and its indications were changed to those of the mercurial 

 barometer. 



September, 1854. 4th. The sudden rise of the barometer between 6 and 7 A. M. is indicated by both 

 instruments. There is apparently no cause for this singular change, so far as is shown by the 

 remaining meteorological observations at these hours. 



10th and llth. Barometer not read during four hours, on account of the darkness. 

 14th. The readings at 7 and 8 P. M. were changed from 29.65 to 29.56; a correction confirmed by 



the aneroid readings. 

 30th. The barometer stand removed to the most forward stanchion of the cabin. Height above 



the water-line, one foot six inches. 



October, 1854. 2d. The original record has the readings 30.2, 30.4, etc., for the hours 19 P. M., etc. 

 It should evidently read 30.02, 30.04, etc., as given in the preceding abstract, and as confirmed 

 by the aneroid readings. Similar mistakes in the displacement of a decimal have occurred in 

 two or three other cases. 



22d. Mercurial barometer in cabin against stanchions amidships. Height of cistern, six feet. 

 November, 1854. 4th to 10th. No record for this interval. 

 December, 1854. 10th. The star in front of the figures indicates that the decimal places refer to 28 



inches. 



20th. The mercurial and aneroid barometers were removed to-day ; the mercurial barometer being 

 placed six inches lower than before, and the aneroid placed two feet below it. 



