266 



Reports on Special Researches 



Observatorj' in March 1908. The geographical position of Lukiapang Observatory is 

 31 19'.05 north latitude, and 121 02'.4 east of Greenwich. 



The Observatory standards were: Elliott magnetometer No. 49 (same^ as used in the 

 previous comparisons at Zikawei) and Schulze earth inductor No. 42. The C. I. W. instru- 

 ments used were: C. I. W. magnetometer No. 12 and Dover dip circle No. 206 (needles 

 1, 2 of No. 206, and needles 5, 6 of No. 178). 



The stations occupied for D and H observations were the "Elliott Pillar" {D) in the 

 absolute house (D), and "Edmunds Pillar" {F) in the grounds about 18 meters southwest 

 of Z). The same mark was used at both stations, viz, the regular Observatorj^ mark on the 

 south wall of the compound; the azimuth of this mark, as furnished bj^ Reverend J. de 

 Moidrey, at Pillar D is 3 47'.0 west of south, and at Pillar F is 357 08'.4 west of south. 

 When either magnetometer is mounted at F, one footscrew is directly to the north; when 

 mounted at Z), however, one footscrew is to the south. The method of comparisons for 

 D and H was that of simultaneous observations and exchange of stations. The //-values, 

 as tabulated, are derived from 1 set of oscillations, 2 sets of deflections, and 1 set of oscilla- 

 tions. The Observatorj' values are the final ones cominunicated by the Reverend J. de 

 Moidrey in his letter of October 3, 1914. 



As it was not possible to move the Observatory earth inductor so as to afford an 

 exchange of stations, the following method for the inclination comparisons was carried out 

 in the absolute house: dip circle No. 206 was mounted on pillar h, 1 meter north of pillar c, 

 on which earth inductor No. 42 is mounted ; observations were made alternately with No. 42 

 and No. 206, the inductor-coils being stationary while No. 206 was in use and the needles 

 of No. 206 being removed while No. 42 was observed with. A complete dip-comparison 

 consisted of: (1) Observations with the earth inductor according to the usual method of 

 the Observatory; (2) dip with one pair of needles of No. 206, ends "A" down; (3) earth 

 inductor same as (1); (4) dip with second pair of needles of No. 206, ends "A" down; 



'All values are referred to station !>, Da = F I'.O. 



(5) earth inductor same as (1) ; (6) second half of dip with second pair of needles of No. 206, 

 ends "B" down; (7) earth inductor same as (1); (8) second half of dip with first pair of 

 needles of No. 206, ends " B " down; (9) earth inductor same as (1) ; the mean of the earth- 

 inductor observations (1), (3), (5), (7), and (9) thus corresponded in time with the mean of 

 the dip-circle observations (2), (4), (6), and (8). 



'Somewhat different values of the constants, for example of P, appear to have been used in 1911 from those in 1907. 



