42 



Ocean Magnetic Observations, 1905-16 



Form 25a, below, shows specimen computations of horizontal intensity (H) from the 

 total-intensity observations, made with sea dip-circle 189 during the swing at San Francisco 

 on May 25, 1908. The upper half, marked I, gives the computation of H, based on the 



Computation of Horizontal Intensity from Total-Intensity Observations, San Francisco, May 25, 1908 



(Form 25a) 



deflection observations, of which specimens for two headings (N, NE) are presented by 

 Form 12a, page 40. In the formula, / is the inchnation resulting from deflection obser- 

 vations on the corresponding heading with all corrections to standard apphed, which, for all 

 headings, amount to — 0?08 (see p. 69). For example, turning to Form 12a, the mean /, 



