332 



CARNEGIE INSTITUTION OF WASHINGTON. 



northern tracks approaching and leaving Sitka are somewhat barren of decli- 

 nation results, owing to the cloudy and foggy conditions that prevail in this 

 region. The largest negative corrections occur in two separate regions. One 

 of these lies between the one hundred and fiftieth meridian of west longitude 

 and the Asiatic coast, the other is between the imaginary diagonal from 

 Panama and the South American coast. The maximum negative errors of 

 about 2?4 are also found in a high latitude. 



The many intersections of the tracks of the two vessels afford important 

 information. If the dates of observations made on intersecting passages are 

 widely separated, the results will furnish data for the calculation of the annual 

 change. If, on the contrary, the elapsed time is sufficiently short the agree- 

 ment of the results will be some measure of their accuracy. 



Table 2, of annual changes in magnetic declination for the Pacific Ocean, 

 determined aboard the Galilee and the Carnegie, shows the comparison with 

 the chart values given on the latest British and United States charts. The 

 annual change is not given on German charts. The annual changes shown in 

 column headed C. I. W. are derived from intersections where observations 

 have been repeated after an interval of more than 4.3 years. It will be seen 

 that, with few exceptions, the annual changes deduced from the observations 

 of the Galilee and the Carnegie are numerically larger than those given by the 

 charts. The distribution of algebraic signs agrees in a general way with the 

 signs of the chart-corrections shown in plate 1. There is, however, one 

 notable exception: the last value in the table is +0?10, which falls between the 

 larger positive and negative chart-corrections. The annual change on the 

 island of Tahiti, which lies approximately in latitude 17 ?5 south and longitude 

 149?5 west, is 4-0?07 according to the Galilee and Carnegie shore observa- 

 tions. The annual change at Suva, Fiji Islands, approximately in latitude 



Table 2. — Annual changes in magnetic declination for the Pacific Ocean, determined aboard 



the Galilee and the Carnegie, and compared with chart values for the period 1906-1913. 



A positive sign indicates a motion of north end of compass needle to east. 



18° south, longitude 181 ?5 west, is — 0?01. The annual change at Honolulu 

 is practically -H0?04; the geographic position is approximately 21° north and 

 158° west, about midway between the third and fourth values of the table, but 

 somewhat nearer the positive value. 



