RECORD AND DTSCUSSION OF THE ATMOSPHERIC PRESSURE. 



The barometric observations at Van Rensselaer Harbor, North Greenland, wore 

 made hourly, and commence June 8th, 1853. The record now available, however, 

 commences with June 27th, 1853, and extends to January 24th, 1855. The mean 

 daily values subsequent to this date, up to April 22d, 1855, inclusive, together 

 with the corresponding mean temperature, are to be found in Appendix No. XII. 

 second volume of the Narrative of the Expedition. It is proposed to discuss here 

 the observations taken between September 1st, 1853, when the brig entered her 

 winter quarters in Van Rensselaer Bay, and January 24th, 1855, at which date 

 the log-book on hand terminates. 



Iihstrumenls. — The expedition was provided with a mercurial barometer and two 

 aneroids. The mercurial marine barometer was made for Dr. Kane by Mr. 

 Tagliabue, of New York. Its length was thirty-three and a half inches; it had a 

 brass scale seven inches in length, and a glass cistern with an adjusting point for 

 the surfiice of the mercury. In its adjustment, the correction for capillarity was 

 included.^ The readings are expressed in English inches. The aneroids have the 

 numbers 4796 and 1400. Of these, the iirst one was read daily (and hourly) from 

 the commencement of the record (June 27th, 1853) till its conclusion (January 

 24th, 1855). That aneroid 479G (and not 1400) was thus used, I infer from a 

 note in Mr. Sonntag's report dated Godhavn, September 12th, 1855, and in which 

 he refers to the comparisons between this aneroid and the mercurial barometer, 

 for the purpose of deducing the corrections to the former. These comparisons, as 

 found recorded in the volume containing meteorological constants, commence with 

 September 30th, 1853, and end on January 9th, 1854—65 in number. 



The readings of the mercurial barometer commence October 24th, 1853, and 

 terminate with January 24th, 1855. The preference has been given to these 

 readings. The indications of the aneroid were only used for the time between 

 September 1st and October 24th, 1853; its readings are also valuable as corrobo- 

 rating those of the mercurial barometer. 



The aneroid was kept on deck till September 19th, 1853, 9 A. M., when the 

 temperature was so low that the attached thermometer foiled to record. The 

 instrument was then taken into the cabin; its position there was six feet lower 

 than on deck. 



In his reduction of a part of the above 65 comparisons between the mercurial 



' The above information of tlie construction of tlie instnmieiit was roccivod from the maker. Scnle 

 !uul cistern were conneetcil ^)\• lirnss. 



