18 



Land Magnetic Observations, 1911-13 



'For explanation of types, see p. 12. 



^For period July 31 to August 16, 1911. 



'For period August 17 to December 1911; change pronounced but cause unknown. 



'Subsequent to November 10, 1913; change due to sudden change in polarity-difference. 



'The final compilation of corrections for circle 200, used in standardizing 71, showed that the provisional corrections adopted for 206 in 

 Volume I for dip +31 are too great negative, so that the fin.il corrections for 71 should be as given above and the dip values published in 

 Volume I should be corrected, accordingly, by appl.ving +0'.9. 



This instrument, used by the Australasian Antarctic Expedition during 1911 to 1913, was found generally an unsatisfactory type for polar 

 work, owing to formation of frost in the jewel-bearings; for this reason it was also necessary to reject tlie observations for total intensity made 

 with this instrument. 



