Specimen Observations on the Galilee 



45 



The inclination observations made with the regular dip-needle are treated in a similar 

 manner. Specimens of these observations for May 28 are given in Form 10a, page 44. It 

 will be noticed that the observations were made with sea dip-circle 189, using regular dip- 

 needle No. 5, polarity of needle not being reversed. The available time did not permit 

 reversal of polarity on each heading, as might otherwise have been desirable, since in 

 frequent handling of the needle there was risk of injury to its pivots, thereby vitiating the 

 observations of the entire swing. 



Determination of Inclination Deviations, San Francisco Bay, May 25, 1908 



(Form 236) 



The necessary correction on account of non-reversal of polarity was determined from 

 the shore observations at San Francisco. This correction, together with reduction to 

 standard, amounted to — 0?03. Applying this, the mean observed inclination (7„), 

 on May 28, both helms, was -f 62?33 and the resulting value of A„ +0?23. 



Summary of Results of Swings, San Francisco Bay, May 23, 25, and 28, 1908. 



The table below summarizes the results of the deternuiiations of the various deviation- 

 coefficients from the swings of the Galilee in San Francisco Bay, May 23, 25, and 28, 1908, 

 as follows: 



I. Declination deviation-coefficients for position on observing bridge occupied by 

 standard compass, expressed in decimals of a degree. 



II. Declination deviation-coefficients for position on observing bridge occupied by sea 

 deflector, expressed in decimals of a degree. 



III. Inclination deviation-coefficients for position on observing bridge occupied by sea dip- 

 circle, expressed in decimals of a degree. 



IV and IVa. Horizontal-intensity deviation-coefficients for position on observing bridge 



occupied by sea dip-circle, expressed in units of the fourth decimal c. g. s. 

 V. Horizontal-intensity deviation-coefficients for position on observing bridge occupied 

 by sea deflector, expressed in units of the fourth decimal c. G. s. 



The column-headings, together with the remarks, will enable the reader readily to 

 follow and to interpret the various entries. For explanation of the various symbols used, 

 see pages 31-32. The probable errors tabulated are those of the observed deviation on a 

 single heading, as computed by the formula given in the lower part of Forms 23 and 23a, 

 pages 36 and 39. They will serve as a relative measure of the accuracy of the observations. 



An inspection of the figures shows that, in general, the results of the closing swings 

 were highly satisfactory. In some respects even superior results have been obtained from 

 swings at other places. (See, e. g., results at San Diego, February 26-March 1, 1906, 

 given in Tables 25 and 26, pages 82-83.) 



