44 



Ocean Magnetic Observations, 1905-16 



Analyzing these by means of Form 23a on page 39, the following deviation-coefficients are 

 derived: 5,= +0?18; C,= +0°67; Z),= -0?11; E,= -0°Ol. The probable error of 

 the deviation of a single heading is ^0?05 or =i=3'. 



Magnetic Observations on Swing: Inclination (I) 



(Form 10a) 



Station: San Francisco Bay 

 Date: May 28, 1908, A. M. 

 Dip Circle: 189 



Chron.: H. W. 

 Needle No: 5 



Obs'r: P. H. D. 

 Rec'd'r: G. P. 



End of needle marked A north. Micro. A on A. Ship's Head: N. 



Circle East 



Needle Face East 



242.0 

 42.5 

 41.5 

 43.0 



N 



62.0 

 62.8 

 62.0 

 62.7 



242.3 62.4 



+62?35 



Circle West 



Needle Face West 



297.0 

 98.8 

 96.5 

 98.5 



N 



117.0 

 18.0 

 17.0 



18.2 



+62?35 



297.7 117.6 



+62?35 



Circle West 



Needle Face East 



296.8 

 99.5 

 96.5 

 98.0 



N 



116.2 

 17.7 

 16.2 

 18.3 



297.7 117.1 



+62?60 



Circle East 



Needle Face West 



241.5 

 42.0 

 41.2 

 42.5 



N 



61.5 

 62.8 

 61.5 

 62.2 



Mean: +62?30 



+62?25 



241.8 62.0 



+61?90 



End of needle marked A north. Micro. A on A. Ship's Head: NE. 



Circle East 



Needle Face West 



242.0 

 42.7 

 41.8 

 43.0 



N 



62.0 

 62.5 

 62.0 

 62.8 



242.4 62.3 



+62?35 



Circle West 



Needle Face East 



297.2 

 98.0 

 97.0 

 98.0 



N 



116.8 

 17.7 

 17.0 



17.8 



+62?45 



297.6 117.3 



+ 62?55 



Circle West 



Needle Face West 



296.5 

 98.0 

 96.8 

 98.7 



N 



117.0 

 18.2 

 17.2 

 18.3 



297.5 117.7 



+62?40 



Circle East 



Needle Face East 



242.0 

 43.0 

 41.8 

 42.5 



N 



62 2 

 63.3 

 62.5 

 62.2 



Mean: +62?44 



+62?42 



242.3 62.6 



+62?45 



Ship's Head 



Chron. time of beginning 

 Chron. time of ending 



Mean chronometer time 

 Chron. correction on L. M. T. 



Local mean time 



Mag. mer. for circle east reads 



N 



h m 



5 15 



19 



5 17 

 +3 42 



8 59 

 179° 15' 



NE 



h m 



5 21 



24 



5 22 

 +3 42 



9 04 

 134° 15' 



Remarks 



Helm 



Weather 



Sea 



Wind 



Roll 



Port 



b 



S 







0° 



The mean value of the inclination from the ship observations is +62?30, the corre- 

 sponding value at the same time from the shore being +62?10; hence Ai=+0?20. 

 Applying the computed deviations and ^„ with signs reversed, to the observed inclinations, 

 the corrected values in the fifth and tenth columns result. The observed inclinations 

 varied from61?72 to 63 ?03, hence through a range of 1?31, whereas the corrected values 

 show a range of but 0?16, or 10'. 



