Comparisons of Magnetic Standards, 1915-21 



409 



mile to the southeast with very frequent service, and a third somewhat farther away 

 to the northward with very frequent service. The tram lines occasion noticeable effects 

 at the observing stations. For this reason the inductor comparisons of November 1920 

 were carried out in part at night when the trams were not operating. The station- 

 differences determined in 1915 and 1920 show fairly good agreement; the values used 

 are given in the foot-notes to the tables of results. Director Skey in June 1921 when 

 supplying the final values for the Observatory states that the declination base-line 

 values resulting from the absolute observations on November 9, 10, 11, 12, and 15, 

 1915, indicated east pier = jarrah peg 0'.27 = brass pipe + O'.Gl; the simultaneous 

 absolute observations with the three magnetometers in November 1915 gave east pier 

 = jarrah peg 0'.48 = brass pipe + 0'.54, while those with the two magnetometers 

 in November 1920 gave east pier = jarrah peg 0'.26. The station-differences adopted 

 for all of the declination work were those indicated by the mean of the above results, 

 viz, east pier = jarrah peg 0'.3 = brass pipe + 0'.6. 



Table 3A. Results of Declination Comparisons at the Chrislchurch Observatory, 1915, 1916, and 1920. 



' All values are referred to east pier using the mean station-differences determined from the com- 

 parisons of November 1915 and of November 1920, viz, east pier=jarrah peg 0'. 3 = brass pipe +0'.6 

 (see above). 



' The Christchurch values are from the magnetograms which apply for east pier. 



