DEPARTMENT 01^ TERRESTRIAL MAGNETISM. 237 



in order to obtain the most reliable results; (3) the effects of various mal- 

 adjustments, and (4) the applicability of the instrument for marine work. 

 As the result of this investigation, it was decided to attempt the use of the 

 earth inductor at sea. Accordingly a proper instrument was designed and 

 constructed in the shop of the Department and furnished to the Carnegie 

 at Tahiti in September ; its operation at sea has proved successful. 



Instrumental constants and corrections on the provisional international 

 magnetic standards of the Department have been determined for 7 mag- 

 netometers and 5 dip circles. As heretofore, these standardizations have 

 been made by the method of simultaneous comparisons with the standard 

 instruments. Owing to building operations near the site of the testing 

 observatories, this observational work had to be temporarily discontinued 

 early in September. The reductions of the field observations have been 

 kept up to date. General and specific instructions for field and ocean work 

 have been prepared as necessary. 



Upon the occasion of the tenth anniversary of the founding of the Insti- 

 tution the Department participated in an exhibit at the Administration 

 Building of the work of the various activities of the Institution, furnishing 

 instruments, charts^ and photographs showing the status of the magnetic 

 work. On March 20 the Department also took part in an exhibit of scien- 

 tific apparatus at the National Museum, given under the auspices of the 

 Washington Academy of Sciences. 



The compilation of past magnetic observations, indexing of current liter- 

 ature, and abstracting of publications of special interest have been con- 

 tinued. Requests for information and data have been numerous and varied 

 and have been answered in such detail as has been possible. 



Among foreign visitors who have familiarized themselves with the work 

 of the Department may be mentioned Governor E. Schultz of Apia, Samoa ; 

 Prof. Carl Stormer of Christiania, Prof. Erich von Drygalski of Munich, 

 General J. de Schokalsky of St. Petersburg, Prof. E. Bruckner of Vienna, 

 Prof. E. de Margerie of Paris, Prof. H. Maurer and Prof. F. Jaeger of Ber- 

 lin, Prof. G. C. Chisholm of Edinburgh, Messrs. H. O. Beckit and A. G. 

 Ogilvie of Oxford, Dr. O. Klotz of the Dominion Observatory, Ottawa, and 

 Prof. Bernhard Weinstein of the University of Berlin. 



SHOP WORK. 



Four universal magnetometers of the 19 10 type with some mechanical 

 improvements have been completed. Earth inductor No. 3 as especially de- 

 signed for use at sea was constructed and forwarded to the Carnegie at 

 Tahiti. Owing to the difficulties experienced with the regulation pattern 

 of gimbal stand on account of lack of level and failure to return invariably 

 to the same position, a reversible ball-bearing gimbal stand has been designed 

 and constructed. The knife-edges for this stand have been made of an alloy 

 of platinum and iridium and the bearing surfaces on the gimbal rings are of 



16 — YB 



