DEPARTMENT OF TERRESTRIAL MAGNETISM. 237 



in the report of last year that the site, consisting approximately of 220 

 acres, was obtained by grant from the government of Western Aus- 

 tralia, through the minister for lands and agriculture. Mr. WaUis 

 has been assisted in his arduous task by Observer W. C. Parkinson. 

 Every effort will be made to have the observatory in operation by 

 January 1, 1919. 



Peru. — The erection of the contemplated observatory in Peru has 

 had to be deferred pending the completion of the one at Watheroo. 



Washington. — The standardizations of the magnetic instruments 

 have been made from time to time in the Standardizing Observatory. 

 An interesting series of comparisons was the one carried out in con- 

 junction with the United States Coast and Geodetic Survey by which 

 another control was obtained upon the maintenance of standards 

 (see page 239). The experimental studies in terrestrial magnetism, in 

 atmospheric electricity, and on earth-currents have been continued. 

 Photographic registrations of the atmospheric-electric potential 

 gradient have been obtained throughout the year in the temporary 

 structure on the deck of the laboratory. Likewise some photographic 

 registrations of the electric conductivity have been obtained and 

 various improvements have been made in the recording instruments, 

 which are ultimately to be installed at our observatories in foreign 

 countries. 



RESEARCH WORK IN WASHINGTON. 

 TERRESTRIAL MAGNETISM. 



Owing to various interruptions it was not possible to complete during 

 the year the entire manuscript for Volume IV. However, continued 

 good progress has been made by the present hmited personnel. A 

 great variety of investigations, experimental and theoretical, relating 

 to problems of defense and research, have been conducted by members 

 of the investigating staff in conjunction with various Government 

 bureaus and the National Research Council. The results of much of 

 this investigational work can not be published at present. Some of it 

 will have a direct bearing on our future research and observational work. 



Investigations and experiments were begun with a view to reducing 

 oscillations and deviations of the magnet in ship compasses and dip 

 circles caused by the motions experienced under actual service condi- 

 tions. Pending the construction of an oscillating platform for more 

 elaborate experimenting, several types of swings have been used tem- 

 porarily in the Standardizing Magnetic Observatory to examine the 

 effects produced by oscillating platforms when they are constrained 

 to move in one plane. Although important facts have been obtained 

 by these experiments, it is yet too early for any final conclusions. 



Those taking chief part in the above investigations were : L. A. Bauer, 

 W. J. Peters, J. A. Fleming, J. P. Ault, H. W. Fisk, C. R. Duvall, 



