28 



Land Magnetic Observations, 1905-10 



Specimen Summaries of Constants. 



There is given below, as specimen, a copy of the constants for Magnetometer 

 No. 9, designed by the Department, as also of the constants for a Dover Dip Circle 

 No. 205: 



Constants of C. I. W. Magnetometer No. 9. 



Scale value: 1 division = 1'.48 



Correction of observed declination to provisional International Magnetic Standard: + 0'.7 



(To be applied algebraically, counting east declination positive and west declination 

 negative.) 



Horizontal intensity constants at 20 centigrade: 

 Log C for distance r, 10 being added to the characteristic is : 



25 cm. 

 6.11607 



27.5 cm. 

 5.99052 



30 cm. 

 5.87591 



35 cm. 

 5.67364 



40 cm. 



5.49852 



At temperature t degrees centigrade : 



log C = log C at 20 + (20 - /)0.0000235 

 Table of (20 - /)0.0000235 in units of 5th decimal. 



Temperature coefficient: 

 Induction coefficient: 

 Distribution coefficients: 

 Moment of inertia: 



Magnet qL. 

 Temp. Cent. log tt^K 

 3.37429 



10 39 



20 49 



30 59 



40 69 



g = 0.00044 per degree centigrade 



n = mh = 4.03 



P= +15.01 0=-468 



Inertia bar No. g. 

 Temp. Cent. log K\ 



2.37570 



10 586 



20 601 



30 617 



40 632 



Correction of observed horizontal intensity to provisional International Magnetic Standard: 0.00018H 



(If, for example, the observed value is 0.20000 C.G.S. the corrected value will be 



0.20000 - (0.00018 X 0.20000) = 0.19996 C.G.S.) 



