54 Terrestrial Magnetism 



No. 175. Vol. III. BAUER, L. A., W. J. PETERS, J. A. FLEMING, J. P. AULT, and 

 W. F. G. SWAN. Ocean Magnetic Observations, 1905-1916, and 

 Reports on Special Researches. (Researches of the Department of 

 Terrestrial Magnetism.) Quarto, vn+447 pp., 24 plates, 35 figures. 

 Published 1917. Price $10.00. 



This volume presents the final results of all magnetic observations made at sea, 

 on the chartered vessel, the Galilee, 1905-08, and on the specially constructed vessel, 

 the Carnegie, 1909-14; also the results of the shore magnetic observations made in 

 connection with the work of the two vessels; the preliminary results of the mag- 

 netic observations made on the Carnegie, 1915-16 (October), are also given. The 

 "Tables of Results" contain the values of the magnetic declination, the inclination, 

 and the horizontal intensity of the earth's magnetic field. For the Galilee ocean 

 work there are 443 tabular entries and for the Carnegie about 2,750, a total for 

 the two vessels of about 3,200. After a general introduction and a brief account 

 of previous ocean magnetic surveys, the magnetic work of each vessel is treated 

 separately. The construction of the Carnegie in 1909 is described and illustrated. 

 A special feature of the Carnegie work is the full account of the instruments 

 devised by various members of the Department of Terrestrial Magnetism, and 

 constructed in the Department's instrument shop, including descriptions and illus- 

 trations of the marine collimating compass for magnetic declination ; the sea 

 deflector for horizontal intensity and declination ; the sea dip-circle for inclination 

 and total intensity; the marine earth-inductor for inclination, and a reversible 

 gimbal stand. The descriptions also give the scheme or method of observation with 

 each instrument. 



The section on geographic position at sea is given special treatment under the 

 Carnegie work, and specimens of observations and computations are added. A 

 brief account is given also of special investigations. A general statement, accom- 

 panied by diagrams, is made regarding the extent and character of the corrections 

 which the existing magnetic charts require in order to make them conform to the 

 observations on the Galilee and the Carnegie. Under extracts from the com- 

 mander's field reports are found, among other matters, notes on the occurrence of 

 thunder at sea observed on the Carnegie's cruise, 1915-16, and an account of the 

 Carnegie's sub-Antarctic voyage of 1915-16. . 



The special report by L. A. Bauer and W. F. G. Swann deals with the "Results 

 of the atmospheric-electric observations made aboard the Galilee (1907-08) and 

 the Carnegie (1909-16)." The introduction, by L. A. Bauer, summarizes the con- 

 siderations determining the extent of the program of scientific work possible aboard 

 such vessels as the Carnegie and Galilee. Next is given a compilation of the main 

 atmospheric-electric results obtained at sea by the Department since 1907, as based 

 on the field reports. A greatly increased program of atmospheric-electric work 

 was undertaken on the Carnegie's fourth cruise (1915-16), and the paper contains 

 a full account and discussion of W. F. G. Swann of the results obtained on 

 this cruise. 



