240 CARNEGIE INSTITUTION OF WASHINGTON. 



tribution coefficients for different instruments were continued; thus 

 far the tentative conclusions reached in last year's report are borne out. 



The standardization and calibration of magnetic and atmospheric- 

 electric instruments on board the Carnegie were completed at Wash- 

 ington promptly after the return of the vessel. The compilation of 

 corrections and constants necessary for the final reductions of the 

 Carnegie work since the pubhcation of Volume III of the Researches 

 of the Department are under way. 



An extensive equipment, including instruments, constants, instruc- 

 tions, miscellaneous tools and appurtenances, and forms, was made 

 ready early in 1918 for the Amundsen Arctic Expedition, which it is 

 expected will require about 5 years to accomplish its proposed work. 



The work of the instrument shop during the year may be classified 

 about as follows: Equipment, 13 per cent; experimental, 14 per cent; 

 improvement of instruments, 11 per cent; repairs of instrumental 

 equipment, 32 per cent (this latter item is rather large because prac- 

 tically all field instruments have been returned to the office after long 

 periods of service and have required much overhauling and repairing) ; 

 special emergency work for outside parties, 25 per cent; miscellaneous, 

 including maintenance and stock charges, 5 per cent. During the 

 year three special compass variometers were designed and constructed, 

 together with their gimbal stands, also two special artificial horizons 

 and appurtenances for use in the navigation of aeroplanes. A con- 

 siderable part of the instrumental work was in connection with the 

 study of designs for possible stabihzing devices and of improvements 

 in instruments to eliminate oscillations and deviations, brought about 

 by linear accelerations causing tilting of the magnetic needles in an 

 instrument on board ship. 



Considerable time was devoted to the overhauling, remaking, and 

 modification of magnetometer 8 and dip circle 205 for use on the 

 Amundsen Arctic Expedition. Because of the low temperatures to 

 be encountered, all parts of these instruments, so far as possible, 

 that are handled with the fingers during observational work were 

 provided with celluloid caps to prevent the bare fingers from touching 

 the metal and also to increase somewhat the diameters of the clamping 

 and adjusting screws to facilitate handling. In connection with these 

 improvements a dip-needle Hfting and turning device was designed 

 for the dip circle; it was feared, however, that this device, since it 

 depended for its successful operation somewhat on the sense of touch, 

 would not be altogether practicable for use in the Arctic, and it was 

 therefore removed from the instrument and the program of observa- 

 tions was so arranged that the necessity for handling the needle and 

 turning it on its bearing was reduced to a minimimi. 



The following field instruments were reconstructed during the year; 

 magnetometers 8, 9, 13, and 16; dip circles 172, 177, 205, 206, and 222; 



