349 



with the marked end of the deflecting bar to the East and to 

 the West respectively. The value of the constant k is given 

 by the formula 



/^ = M +- j tan0; 



Q denoting the angle corresponding to one division of the 

 scale, and — the ratio of the torsion force to the magnetic 



F 



force. When the mirror is employed, the formulae of re- 

 duction are similar, if only we substitute 2 m and 20 for u 

 and Q. The following Table gives the values of the constants 

 employed in the reduction: 



I 6 



H 



F 



logk 



-5 (coll.) 

 •5 (mirr.) 

 •375 — 

 ■313 — 



49"-158 

 58"-766 



•00180 

 •00162 

 •00255 

 •00292 



6-37795 

 6-75643 

 6-75684 

 6-75700 



The following Tables contain the calculated results: the 

 values of ^(we — «jr) are corrected for the changes of declination 

 which occurred in the interval of the two readings Ug and w,t,. 

 Series I. and II. 1 = I' = -5. 



D. 



I. 



II. 



^(ne—nu) 



u 



\(ne—nu) 



u 



4.5006 

 6.0010 



194-78 

 82-51 



2° 39' 45" 



1° 7' 43" 



194-22 

 82-26 



2° 39' 18" 

 1° 7'30"-5 



Series III. and IV. / z= -5, V = •375. 



D. 



III. 



IV. 



\{ne —nn) 



u 



\ (Ue — ««,) 



u 



4-0010 

 5-0015 

 6-0019 



242-30 



123-31 



71-40 



3° 56' 25" 

 2° 0'53" 

 l°10'4"-5 



242-52 

 123-50 



71-38 



3° 56' 38" 

 20 \i \it 



1°10' 3" 



2 G 2 



