244 



Ocean Magnetic Observations, 1905-16 



Specimen Determinations of Inclination Corrections of Sea Dip-Circle 



Station: A and B, Suva Vou, Fiji 

 InslTumenl: Sea dip-circle 189 



Dale: June 17, 18, 19, 1912 



06sVs.- H. D. F. and 

 H. M. E. 



'AH values are referred to A; A =B -0.1. „ , „t c. j j n>-r 



'The correction applied to observed values by earth inductor 2, to reduce them to C. 1. W . Standard, was -0.7. 

 ^IDBS is the designation for the mean value for needle 7 in direct and reversed positions when deflected by needle 8 at the 

 short deflection-distance; iDRL is the corresponding designation for the long deBection-distance. 



Terrestrial Magnetism. A description of the instrument and accessories, its theory, an 

 explanation of its use, and specimen observations and computations for magnetic inclina- 

 tion on board ship, are given on pages 196-202 and 221-224. 



At each shore station comparison observations are made between the marine earth- 

 inductor and the standardized land earth-inductor, to control any possible change in the 

 inchnation correction of the first instrument, as well as its constancy. Specunen determi- 

 nations at a shore station with the marine inductor, and a specimen summary of the results 

 for an entu-e set at a smgle shore station, are given on pages 245-246. 



Marine earth-inductor 3.— Marine earth-inductor 3 was used on the Carnegie during 

 Cruises II (from September 1912), III, and IV. This instrument, with its special rever- 

 sible gimbal-stand for use on board ship, was designed and constructed by the Department 

 of Terrestrial Magnetism. It is provided with a marine moving-coil galvanometer, 

 designed and constructed by the Leeds and Northrup Conipany. The adopted inclination- 

 correction from all available data is, for all values of inchnation, -l!0. 



