202 REIPORTS OF INVESTIGATIONS AND PROJECTS. 



There has also been made in the shop an improved form of deflector, based 

 on the Director's design, as already used in the cruises of the Galilee for the 

 determination of horizontal intensity at sea. A description of this improved 

 deflector has not yet been published ; the observations prove that the expecta- 

 tions of increased accuracy have been realized. A similar deflector device 

 has been attached to the marine collimator. 



The construction of magnetometers Nos. 12, 13, and 14 has been begun, 

 and it is hoped will be completed in the coming year. Nos. 12 and 13 have 

 been specially designed as theodolite magnetometers of a very portable form. 

 Each instrument, it is expected, will not weigh more than 20 pounds with its 

 entire equipment except tripod. Magnetometer 14 is designed as a universal 

 instrument, serving for the determination of all three elements. This in- 

 strument is also of light pattern, and will probably in its entirety not weigh 

 more than 25 pounds. . . -i-'-..^ 



In addition to the work as above stated the various astronomical, meteoro- 

 logical, and other instruments for the Carnegie were put in good condition. 



One valuable result of the possession of an instrument shop has been in 

 the reduction of the amount of time required to put a newly purchased 

 instrument in satisfactory adjustment and condition for work. Above all, 

 however, the chief value lies in the fact that the instruments may be con- 

 structed entirely under our own supervision and all metals carefully tested 

 as to non-magnetic properties ; in consequence, the instrumental corrections 

 are being largely reduced. 



Mr. J. A. Fleming had general supervision of the shop, Mr. Adolf Widmer 

 being chief mechanician. Mr. Widmer has shown considerable skill as well 

 as conscientious care and interest in the tasks set before him. 



SPECIAL INVESTIGATIONS. 



An investigation as to the relation between solar and terrestrial magnetic 

 phenomena has been undertaken, in cooperation with Professor Hale, who 

 furnished the required solar data. A comparison of the changes in solar 

 activity and those of terrestrial magnetic activity during the period May, 

 1906, to January, 1909, has revealed various interesting results, the chief one 

 being that an increase in solar activity is apparently associated with an effect 

 on the earth's magnetization, which is equivalent to a decrease in the mag- 

 netic moment or mean intensity of magnetization. A preliminary communi- 

 cation was made to the American Philosophical Society last April, as also to 

 the British Association at its Winnipeg meeting in August. 



Other investigations have already been described in the sections to which 

 they refer. 



In conclusion, it gives me much pleasure to refer, as in past years, to the 

 faithful and valuable services rendered in the office by Mr. J. A. Fleming, 

 Magnetician in Charge. 



