31() CARNEGIE INSTITUTION OF WASHINGTON. 



observatories. Though the labor involved has been great, the results 

 have proved an adequate recompense. It has been possible to settle on 

 universal or "international magnetic standards" satisfying all require- 

 ments, both theoretical and practical, and to transport and reproduce 

 them in remote regions with all necessary accuracy. (Cf. p. 328.) 



The manuscript of Volume III (Ocean Magnetic Observations, 1905- 

 1913, and Reports on Special Researches by L. A. Bauer and W. J. 

 Peters) is in good progress, as is also that of Volume IV (Ocean and 

 Land Magnetic Observations, 1914-1916, and Reports on Special 

 Researches by L. A. Bauer, J. P. Ault, and H. W. Fisk). 



In addition to the work above mentioned and that shown by the 

 abstracts of papers (pp. 325-342), and the instrumental work described 

 below, a variety of investigations were completed or are in progress. 

 Chief of these may be mentioned the following: 



(a) Investigations relating to the sources of error in terrestrial-magnetic 



measurements, and of the causes for changes of instrumental con- 

 stants, etc., by L. A. Bauer, J. A. Fleming, H. W. Fisk, C. R. Duvall, 

 and W. F. Wallis. 



(b) Further improvements of ocean instrumental appliances, by L. A. 



Bauer, W. J. Peters, and J. A. Fleming. 



(c) Continuation of investigation of the possible relationship between 



changes of solar radiation and terrestrial magnetism, by L. A. Bauer. 

 (A paper was read before the meeting on Atmospheric Physics, 

 Section B, American Association for the Advancement of Science, 

 San Francisco, August 4, 1915; see abstract, pp. 330, 331.) 



(d) Preparatory studies of methods for reducing magnetic observations 



to a common epoch, by L. A. Bauer and H. Bateman. 



ATMOSPHERIC ELECTRICITY. 



Continued good progress has been made during the year by Dr. 

 W. F. G. Swann, assisted by Dr. S. J. Mauchly, in the theoretical and 

 experimental study of instrumental appliances for measurements in 

 atmospheric electricity. In consequence, it was possible to start out 

 on the present cruise of the Carnegie with greatly unproved instruments, 

 mounted in a specially constructed deck-house. The installations on 

 the Carnegie were completed at Brooklyn and Gardiners Bay under 

 Dr. Swann's direct supervision, and Dr. Mauchly accompanied the 

 Carnegie as far as Panama, in order to perfect the operation of the new 

 instruments and to assist in the inauguration of the observational 

 program to be carried out on the cruise by Observer H. F. Johnston. 



New methods, or considerable modification of methods of former 

 investigators, have been devised for the measurement of all the atmos- 

 pheric-electric elements recorded, and special attention has been given 

 to the problem of increasing the speed of the observations and reducing 

 to a minimum all necessary work connected therewith. It has thus 

 become possible for one observer, with a little assistance from a second 

 observer, to make, during a period of about 2.5 hours, 3 measurements 

 of the conductivity, 3 measurements of the ionic content, measure- 



