242 CARNEGIE INSTITUTION OF WASHINGTON. 



Continuous records with a Benndorf recording electrometer of the potential 

 gradient of the atmosphere at the station on the mainland were obtained with 

 comparatively small loss throughout the year. A second Benndorf recording 

 electrometer for registration of potential gradient was installed during August 

 in the small, specially designed house built at the expense of the Department 

 inside the reef about one-third mile off shore. Mr. A. Tyndall, engineer in 

 charge of the Public Works Department of Western Samoa, looked after the 

 designing and construction of this special house, which has been found satis- 

 factory in every way. To control reduction-factor determinations for the 

 equipment at this station, an automatic tide-gage after the design of the 

 United States Coast and Geodetic Survey was ordered. Occasional diurnal- 

 variation observations of the conductivity of the atmosphere were secured. 



In addition to the observatory magnetic work by Mr. Westland and the 

 atmospheric-electric work by Mr. Thomson, the latter has maintained, under 

 the auspices of the New Zealand government, an enlarged program of meteoro- 

 logical work, so that now the Apia Observatory serves as the central station 

 of a service embracing the Fiji, Tonga, Marshall, and New Hebrides islands. 

 Mr. Thomson also initiated the resumption of upper-air work, the first pilot- 

 balloon flights being made in June. Cooperation in this work was extended 

 by the United States Weather Bureau and the Canadian Meteorological 

 Service, the former placing on indefinite loan at Apia balloon-filling equip- 

 ment and pilot-balloon plotting board, while the latter supplied an additional 

 theodolite. 



The New Zealand government authorities continued unabated pronounced 

 interest in the maintenance of the observatory. As in past years, all equip- 

 ment and apparatus were admitted free of duty. 



MacMillan North Greenland expedition. — In view of the successful coopera- 

 tion with the MacMillan Baffin Land expedition of 1921-22 (see p. 278 of 

 last year's report), advantage was taken of the opportunity presented to 

 cooperate with Dr. MacMillan on his North Greenland expedition of 1923- 

 24, which left Wiscasset, Maine, on June 23. The expedition was equipped 

 by the Department with the requisite magnetic instruments for absolute and 

 photographic work, and with the apparatus for registering the electric poten- 

 tial gradient of the atmosphere at a temporary observatory constructed at 

 Refuge Harbor, Greenland, near the quarters for the winter of 1923-24, in 

 latitude 78° 31' north and longitude 72° 27' west. The program includes also 

 observations with respect to northern lights, meteorology, tides, and the 

 occupation of magnetic stations in Labrador, Greenland, Ellesmere Land, 

 and Baffin Land. Mr. R. H. Goddard, observer of the Department, has 

 immediate charge of the scientific work. 



Maud expedition, 1918 to 1921. — Since last year's report, there was received 

 through the Norwegian legation at Washington, on March 31, 1923, the pack- 

 age containing magnetic records, copies of absolute observations, and original 

 declination magnetograms covering one season's work, originally intrusted to 

 Knudsen and Tessem, members of Amundsen's party, who were lost in 1919 

 during the return journey to Dickson Island. The records were recovered by 

 the Russian explorer Begitsjer on his expedition of 1921 to 1922. The 

 absolute observations have been already reduced ^ (see pp. 307-308 of last 

 year's report) . The magnetograms were obtained at the first winter quarters 

 during October 1918 to August 1919, in latitude 77° 32'.6 north and longi- 

 tude 105° 40' east of Greenwich ; the compilations from the records at so high a 

 latitude will contribute valuable data for studies of the diurnal variation and 

 of magnetic storms. 



^ H. U. Sverdrup and C. R. Duvall, Results of magnetic observations on the Maud expedition, 

 1918-1921. Terr. Mag., vol. 27, 35-56 (March-June 1922). 



