318 CARNEGIE INSTITUTION OF WASHINGTON. 



the Sun and the Moon were in the zenith. The momentarily increased 

 magnetization of the Earth for stations near the belt of totahty of 0.012 per 

 cent at 12^30°" corresponded to the amount associated with about a 6 per 

 cent decrease in solar radiation.^ Equally interesting results were disclosed 

 at other times; invariably the positions of the foci of the disturbing forces 

 could be related to the momentary position of the shadow-cone. The indi- 

 cations are that the complete analysis of the eclipse magnetic system will 

 show that it has characteristics analogous to those exhibited by the systems 

 causing the solar-diurnal and the lunar-diurnal variations of the Earth's 

 magnetism. 



Description of glass magnetogram scale used by the Department of Terrestrial Magnetism. 

 J. A. Fleming. Terr. Mag., vol. 24, 154-156 (December 1919.) 



The glass magnetogram scale described is to facilitate reading quickly to 

 the nearest 0.1 mm. the mean ordinates for 60-minute intervals on magneto- 

 grams in accordance with the procedure adopted for the magnetic observatories 

 of the Carnegie Institution of Washington .^ These scales, as constructed in 

 the instrument shop of the Department of Terrestrial Magnetism, are some- 

 what similar to the type introduced by the Potsdam Magnetic Observatory 

 and as used by the United States Coast and Geodetic Survey. The type of 

 scale is described in detail, as well as the method used in measuring magneto- 

 grams. 



The construction and equipment of the Watheroo Magnetic Observatory in Western 

 AustraUa. J. A. Fleming and W. F. Wallis. Terr. Mag., vol. 25, 1-6 



(March 1920). 



The Director of the Department visited Australia in 1911 and conferred 

 with those interested in geophysical investigations. As the result of these 

 conferences. Western Australia was chosen as the site of the Department's 

 first observatory. The general region within which the proposed observatory 

 was tentatively specified to be was between 28° to 36° south latitude and 

 114° to 118° east longitude. 



The necessary field-work in the examination and selection of a site con- 

 forming as nearly as is possible to the requirements was undertaken by Mr. 

 Wallis, with the assistance of Observer Parkinson, in August 1916. It was 

 not until early in March 1917 that the site at Watheroo was finally selected. 

 The site is about 12 miles by road westward of Watheroo, 132 miles from 

 Perth, on the Midland Railway, and in latitude 30° 18' south and longitude 

 115° 53' east of Greenwich, on a fine, level stretch of sand-plain, clear of 

 timber, and covered only with coarse grass and low bushes. 



The observatory buildings, as constructed under Mr. Wallis's direction and 

 supervision, in accordance with designs developed by Mr. Fleming, consist 

 of the following: (a) variation observatory and office; (6) absolute observa- 

 tory; (c) observers' quarters; (d) storehouse and workshop; and (e) miscel- 

 laneous small buildings, including stable, laundry, etc. All are of frame 

 construction, and (a) and (6) are strictly non-magnetic. As it was not possible 

 to get contractors to offer bids on non-magnetic construction, Mr. Wallis 

 found it necessary to purchase his own materials, engage carpenters, and carry 

 on the work himself. Detailed descriptions and illustrations of plans and the 

 finished buildings are included. 



»Terr. Mag., vol. 20, 1915, p. 149. 



*C/. L. A. Bauer, "Procedure at the Magnetic Observatories of the Carnegie Institution of 

 Washington," Terr. Mag., vol. 24. 149-153, 1919. 



