Comparisons of Magnetic Standards, 1905-14 261 



The mean results obtained from these approximate comparisons, after reducing them 

 to I. M.S. fseep. 273), are: 



(26) I. M. S. Tokio (Observatory Tanakadate magnetometer) =+ 0'.6 (6 sets; Aug. 15, 16, 



Sept. 3, 1906). 

 (26a) I. M. S. Tokio (Observatory Tanakadate magnetometer) = +0.00048// (3 sets; Aug. 15, 



16, Sept. 3, 1906). 

 (26b) I. M. S.-Tokio (Observatory Casella dip circle)= -3'.2 (5 sets; Aug. 15, 16, 1906). 

 (26c) I. M. S.-Tokio (Wild earth inductor)= +4'.5 (5 sets; Aug. 15, 16, 1906). 

 The following data will afford .some idea of the possible corrections of one of the stand- 

 ard sets of instruments used in the 1895 magnetic survey of Japan, namely, Tanakadate 

 magnetometer No. 3, and Casella dip circle No. 5615, needle 1. Comparisons were made 

 at Tokio on August 9-11, 1898, between these instruments and those of the Austrian naval 

 vessel, the Frundsberg^ With the aid of the standardizations of the latter instruments, 

 made at Pola in April 1898 and July 1899, the following figures- result, if we also take into 

 consideration the 1895 D and H comparisons at Tokio, obtained bj' Karl Kailer of the 

 Austrian Nayj^, giving them, however, half weight, as they were few^er in number than those 

 of the Frundsherg: 



(a) Pola (Schneider magnetometer) Tokio (Tanakadate magnetometer No. 3)=!'. 8 



(1895 and 1898). 

 (h) Pola (Schneider magnetometer) Tokio (Tanakadate magnetometer No. 3) = 



+0.00079// (1895 and 1898). 

 (c) Pola (Wild inductor) -Tokio (Casella No. 5615, needle 1) = -4'.2 (1898). 



From comparisons" at the Pola Observatory, December 1902-January 1903, the 

 following relations were found between the new Pola magnetometer (Bamberg No. 7904) 

 and the Schneider magnetometer formerly in use: 



(rf) Pola (Bamberg No. 7904) -Pola (Schneider) = -0'.6 (6 sets; Jan. 1903). 



(e) Pola (Bamberg No. 7904) -Pola (Schneider) = - 0.00046// (6 sets; Dec. 1902). 



Combining (a) and (b) with (d) and (e) : 



(/) Pola (Bamberg No. 7904) -Tokio (Tanakadate magnetometer No. 3) = -2'.4 (189.5- 



1903). 

 (!7) Pola (Bamberg No. 7904) -Tokio (Tanakadate magnetometer No. 3) = +0.00033// 

 (189.5-1902). 



With the aid of the C. I. W. comparisons at Pola in 1910 (Tables 18 A, 18 B, 18 C, 

 p. 248) we get, from (/), (g), and (c), assumijig no material changes in instrumental con- 

 stants between 1895 and 1910: 



(/i) C. I. W. -Tokio (Tanakadate magnetometer No. 3)= -2'.7 (1895, 1898, 1902, 1910). 

 (i) C. I. W.- Tokio (Tanakadate magnetometer No. 3) = +0.00087// (1895, 1898, 1902, 



1910). 

 (j) C. I. W.-Tokio (Casella 5615, needle 1)= -4'.1 (1898, 1910). 



In these comparisons at Tokio in 1895 and 1898, the observations were made in two 

 tents, distant from each other about 30 steps, in the recreation grounds in front of the 

 Physical Institute of the University. As the observers did not exchange stations, possible 

 station-differences were not eliminated. 



Reducing to I. M. S. by applying to the C. I. W. values in (h), (?'), and (j) the 

 corrections stated on p. 273, we get as approximate results: 



(26c/) I. M. S.-Tokio (Tanakadate magnetometer No. 3)= -2'.6 (1898). 

 (26e) I. M. S.-Tokio (Tanakadate magnetometer No. 3)= +0.00072// (1898). 

 (26/) I. M. S.-Tokio (Casella 5615, needle 1)= -3'.6 (1898). 

 In view of the uncertainties attaching to the results of the above comparisons, they are 

 not entered in Table A, page 278. 



^Terr. Mag., v. 7, 1902, p. 196. 



'The signs of the declination corrections were reversed so as to apply to east declination positive. 



'Jahrbuch der meteorolog., erdmagnet. und seismischen Beobachtungen, 1902, pp. XXXIX-XLII, Pola 1903. 



