270 CARNEGIE INSTITUTION OF WASHINGTON. 



part of the large correction of the Cheltenham magnetometer on the 

 Department's standard was due to the adopted value of the computed 

 moment of inertia of H26. Dr. Dorsey also prepared a preliminary 

 design for an absolute sine galvanometer for use in the absolute deter- 

 mination of the magnetic intensity. 



Instrumental constants and corrections on the adopted magnetic 

 standards of the Department have been determined for four magnet- 

 ometers, five dip circles, and three earth inductors. A non-magnetic 

 lever comparator has been designed and manufactured for use in 

 measuring magnets. 



Owing to the difficulties generally experienced in the satisfactory 

 determination of the corrections of dip needles to standard and the 

 possible changes in these corrections with geographical variation in 

 magnetic intensity and inclination and with wear of pivots of the 

 needle, it was found desirable to further improve the universal mag- 

 netometer of the Department by replacing the dipping needle by an 

 earth-inductor attachment. Accordingly a combined magnetometer 

 and earth inductor has been designed by Messrs. Fleming and Widmer 

 and constructed in the instrument shop. The instrument consists 

 essentially of four parts: (a) the base, (6) the magnetometer attach- 

 ment, (c) the earth inductor and theodolite attachment, and (d) the 

 galvanometer. The effort has been to secure a compact, portable 

 instrument, with a minimum of loose accessories, for rapid field work 

 of high precision. A galvanometer of the Kelvin type has been 

 specially designed for this instrument. One of these magnetometers 

 has been completed and two others are under construction. (For the 

 article by Messrs. Fleming and Widmer describing the combined 

 magnetometer see Bibhography.) 



Universal magnetometer No. 22 of the 1910 type has been com- 

 pleted and forwarded on order to the Imperial University of Kazan, 

 Russia; magnetometer and earth inductor No. 23 of the nev/ design 

 has been similarly forwarded to the Physical Laboratory of the Tech- 

 nological Institute at Tomsk, Siberia. Earth inductor No. 4 has been 

 completed and supplied to the Royal Alfred Observatory at Mauritius. 



PERSONNEL. 



The personnel during the year was as follows : 



L. A. Bauer, Director; N. E. Dorsey, Research Associate (to March 12); 

 W. F. G. Swann, consulting physicist (June 1-September 28) and chief 

 physicist (from September 29); J. A. Fleming, chief magnetician; W. J. 

 Peters, in command of the Carnegie; H. M. W. Edmonds, H. W. Fisk, J. P. 

 Ault, and W. F. Wallis (from July 1), magneticians; C. R. Duvall, expert 

 computer (from October 11); C. C. Craft, surgeon and magnetic observer 

 alioard the Camecjie; C. W. Hewlett, assistant physicist; E. Kidson, W. H. 

 Sligh (to March 1), H. F. Johnston, D. W. Berky, H. E. Sawyer, H. R. 

 Schmitt, A. D. Power, A. H. Palmer (from February 4 to October 8), D. M. 

 Wise (from April 15), W. C. Parkinson (from June 1), magnetic observers; 

 F. W. Cox (to February 28) and F. Brown (from May 30), assistant ob- 

 servers; C. K. Edmunds (occasional magnetic-survey work in China). 



