252 CARNEGIE INSTITUTION OF WASHINGTON. 



land (see abstract, pages 274-276). In the forthcoming cruise the 

 samples will be collected with the special view of affording information 

 on the variation of radium-content with distance from land. 



The general ocean atmospheric-electric results obtained since March 

 1916 only serve to strengthen the conclusion arrived at in Volume III. 

 They show that, as a general rule, the atmospheric-electric elements 

 are of the same order of magnitude at sea as on land, except as regards 

 the radium-emanation content, which is much smaller on the ocean, 

 and as regards the penetrating radiation, which is also smaller, as 

 would be anticipated from the small value of the radioactive content. 



Special attention has been devoted to the diurnal variation since 

 March 1916, and the results for the diurnal variations of potential 

 gradient, ionic content, and penetrating radiation can now be based 

 upon about 20 sets taken over a complete period of a year. (See ab- 

 stract, pages 281-283.) 



LAND MAGNETIC WORK. 



Though the war has prevented the completion of the magnetic 

 survey of certain land areas for which plans had been made, the follow- 

 ing work was accomplished during the period November 1, 1916, to 

 October 31, 1917: 



1. Africa. — An expedition, led by Observer H. E. Sawyer, through French 



Kongo along the Kongo and Ubangi rivers to Lake Tchad, thence 

 eastward to Anglo-Egyptian Sudan. 



2. Asia. — Expeditions by Observer F. Brown, under the direction of 



Dr. C. K. Edmunds, in Manchuria, southwest China, through the 

 Yunnan province to Bhamo and across the Burma frontier, and 

 finally along the southeast coast of China. 



3. Australasia. — In connection with the establishment of the magnetic 



observatory in Western Australia, Observers W. F. Wallis and W. 

 C. Parkinson made magnetic observations at various points. 



4. South America. — Expeditions by Chief Magnetician Fleming and 



Observers D. M. Wise and B. Jones in the interior of Peru, both 

 in connection with examination of sites for a proposed magnetic 

 observatory in Peru and magnetic-survey work; also an expedition, 

 led by Observer Allen Sterling, in Chile and Bolivia, thence down 

 the Beni and Madeira rivers to Manaos, Brazil. Furthermore, 

 Observers A. D. Power and L. L. Tanguy made magnetic obser- 

 vations at a number of stations in Argentina in cooperation with 

 the Argentine Meteorological Office. 



MAGNETIC OBSERVATORY WORK. 



Western Australia. — ^The site finally selected for the magnetic obser- 

 vatory in Western Austraha is about 10 miles west of Watheroo and 

 about 120 miles north of Perth. The government of Western Australia, 

 through the Minister for Lands and Agriculture, made a grant to the 

 Institution of 160 acres for the building-site of the observatory, with 



