DEPARTMENT OF TERRESTRIAL MAGNETISM. 315 



light observations; investigations based on the accumulated results in 

 atmospheric electricity. 



A statement of some of the important results derived from electric 

 observations made aboard the Carnegie, which have a significant 

 bearing upon theories of atmospheric electricity, will be found on pages 

 354-356. 



Through its extensive ocean work the Department is not only 

 obtaining the chief data pertaining to the geographic distribution of 

 the atmospheric-electric elements, but is also enabled to contribute 

 important data respecting the diurnal and annual variations of these 

 elements. 



It is still true that the Department's station at Washington is the only 

 one in the United States where continuous records of the changes in the 

 electric condition of the atmosphere are being obtained. These records 

 are being consulted by various outside investigators, especially by 

 those who are making studies of the atmospheric disturbances en- 

 countered in wireless transmission. 



STANDARDIZATION AND INSTRUMENT WORK. 



As in previous years, the investigations and work under this head 

 have been conducted in the Magnetic Survey Division, in charge of 

 Mr. J. A. Fleming, to whose report on pages 337-340 reference may be 

 made concerning details. 



Reference has already been made on page 312 respecting interesting 

 results obtained from the comparisons of instruments of various types, 

 these results having important bearings upon methods of observation. 

 (See also p. 337.) 



The construction of sine galvanometer No. 1, as designed by Dr. Bar- 

 nett, for determining in absolute measure the horizontal intensity of the 

 Earth's magnetic field, was completed. It has already been stated on 

 page 313 that comparisons made under Mr. Fleming's direction between 

 the sine galvanometer and the Department's standard magnetometer 

 showed a very satisfactory agreement. 



It will be seen from Mr. Fleming's report (pp. 337-340) that an un- 

 usual amount of construction work in the instrument shop was com- 

 pleted during the year. Aluch of this work was in connection with 

 the designs of instruments of high grade for the varied work of the 

 Department at Washington, in the field, and at its observatories, or in 

 connection with special expeditions. 



Owing to the heavy pressure upon our shop for the appliances re- 

 quired by the Department in its own work and because of the con- 

 tinued scarcity of skilled instrument-makers and high costs of con- 

 struction, it has not been possible to meet in any respect the requests 

 we continue to receive from foreign institutions for instruments of our 

 design. 



