260 



Ocean Magnetic Observations, 1905-16 



that there will be many cases in which the values of declination, or of inclination, will be 

 changed by more than 0?1, and the values of the horizontal intensity by more than 0.001 

 c. G. s. Since the errors of the present magnetic charts are many times greater than the 

 possible corrections mentioned, the preliminary values here pubUshed wiU answer all prac- 

 tical requirements. As will be seen, the tables (pp. 288-295) apply to the present cruise 

 (IV) and extend up to the arrival of the Carnegie at San Francisco, September 21, 1916. 

 For the reasons stated, the values of the magnetic declination and of the incUnation are 

 tabulated only to the nearest 0?1, and the values of the horizontal intensity to the nearest 

 0.001 c. G. s. 



DISTRIBUTION OF STATIONS. 1 909-1 9 1 6. 



The following table shows for each cruise of the Carnegie the number of days at sea, 

 the length of the cruise in nautical miles, the number of tabulated values, respectively, of 

 decUnation, incUnation, and horizontal intensity; next the average time interval as well 

 as the average distance apart between the observations. It wUl be seen that there has 

 been a steady increase in efficiency as the work has advanced, the average time interval 

 and the average distance apart of the observations being both less for the later cruises 

 than for the first. For the total length of cruises, up to end of September 1916 (160,615 

 nautical miles), the magnetic observations, whether of declination, inclination, or hori- 

 zontal intensity, were made practically every day at an average distance apart of 93 to 

 138 miles. 



Table 66. — Summary showing the Distribution of the Carnegie Magnetic Observations, 1909-1916 {September). 



OBSERVERS AND COMPUTERS. 



The Table of Ocean Results differs from the Table of Land Results, pubUshed in 

 Volumes I and II, in one other respect besides those already stated in the foregoing explana- 

 tions, namely, that the observers' initials, for practical reasons, had to be omitted. The 

 magnetic results for any one day are the combined product of all the observers aboard at 

 the time. Those who took part in the observations for the various cruises are as foUows: 



Carnegie, Cruise I. — J. P. Ault, L. A. Bauer, C. C. Craft, E. Kidson, W. J. Peters, and 

 R. R. Tafel. 



Carnegie, Cruise II. — L. A. Bauer, C. C. Craft, H. M. W. Edmonds, E. Kidson, H. D. 

 Frary, C. W. Hewlett, H. F. Johnston, W. J. Peters, and H. R. Schmitt. 



Carnegie, Cruise III. — J. P. Ault, H. M. W. Edmonds, H. F. Johnston, and I. A. Luke. 



Carnegie, Cruise IV. — J. P. Ault, H. M. W. Edmonds, H. F. Johnston, B. Jones, I. A. 

 Luke, F. C. Loring, and H. E. Sawyer. 



The chief persons who have taken part, at various times, in the determination of 

 instrumental constants and comparisons at Washington in the final office reductions, or in 

 the preparation of results for pubUcation, are: J. P. Ault, L. A. Bauer, J. J. Carey, C. C. 

 Craft, C. R. Duvall, H. M. W. Edmonds, C. C. Ennis, H. W. Fisk, J. A. Fleming, H. D. 

 Harradon, H. F. Johnston, E. Kidson, R. R. Mills, J. H. MiUsaps, W. J. Peters, A. D. Power, 

 H. R. Schmitt, and J. A. Widmer. Those whose names are italicized have borne the chief 

 brunt of the work at Washington. 



