4 ASTRONOMICAL OBSERVATIONS 



Tlie following observations were made with the Gambey sextant and artificial 

 mercurial horizon. The mercury was covered with a glass roof, the sides of which 

 were reversed during the observations, in order to eliminate any error arising from 

 a want of parallelism in the surfaces of the glass. The zero-point of the sextant 

 w^as examined, and its index determined for each set of observations. The positive 

 sign of the index error indicates that the zero-point is on the large arc, and that 

 the correction to the observed altitude is subtractive. The long astronomical 

 telescope belonging to the sextant was always used.^ In Appendix, No. X, of the 

 second volume of the Narrative," Dr. Kane remarks, that the sextants used were 

 made by Gambey, and divided to ten seconds; he believed that an error of ten 

 seconds, depending on the want of parallelism in the glass cover of the horizon, 

 could not exist in the results. 



The time observations, with the transit instrument, made between November 

 18, 1853, and January 10, 1854, will be found recorded and discussed after the 

 completion of the latitude observations ; the following record, and result for time 

 on February 20, 185-4, however, is here inserted, as made with the Gambey sextant, 

 and in order to follow the date as near as may be convenient. 



' Extracted from a Report of Mr. Sonntag's to the Commander, dated "Brig Mariano, Godhavn, 

 September 12, 1855." 

 " See Appendix containing extracts. 



