304 CARNEGIE INSTITUTION OF WASHINGTON. 



reduce as much as possible the mass of the balancing-weights and con- 

 sequent eccentricity of center of gravity of the moving-coil system as 

 regards its line of suspension; a clamp was also added, so that the 

 mo\dng system might be clamped without distortion when the instru- 

 ment was not in use and thus prevent the throwing out of balance 

 caused by the vibrations of the engine when running. Some of the 

 experimental work was in connection with the production of mirrors 

 for laboratory use and with improvement of methods for optical work. 



The improvements and repairs of instruments and buildings, as will 

 be noted, engaged a large part of the time of the shop personnel. The 

 most important part of this work included the overhauling and recon- 

 struction of magnetometers 9, 12, 17, 19, and 21, and of dip-cu*cle 223, 

 all of which were in bad condition because of long and severe service 

 in the field ; minor repairs and reconstruction were affected on marine 

 galvanometer tube 20697, collimator 2, magnetograph 5, conductivity 

 apparatus 5, high-potential storage-battery, and miscellaneous mag- 

 netic, survey, and laboratory instruments and equipment. Building 

 improvements were chiefly concerned with the Experiment Building; 

 non-magnetic lead sash-weights, shades, screens, and switch-boards 

 v/ere designed and made for it. The machine-tool equipment was 

 kept in order and repaired, and was increased by the addition of a tur- 

 ret attachment for one of the lathes. This attachment was needed 

 particularly for the making of instrument screws of non-magnetic 

 material which we have found it impossible to procure from outside 

 manufacturers since the war. 



As heretofore, all of the non-magnetic castings requu-ed in our work 

 have been made in our own foundry under the direction of Mr. C. 

 Huff. About 1,300 pounds of non-magnetic brass, copper, aluminum, 

 and bronze castings, as well as about 1,300 pounds of lead sash-weights, 

 were made during the year. The Department has communicated to 

 the British Admiralty, upon request, the methods developed in its 

 brass foundry for making non-magnetic castings, and instruction was 

 given to representatives of the foundry department of the Bureau of 

 Ordnance of the United States Navy in these methods. 



The personnel of the instrument shop included Messrs. C. Huff, G. 

 H. Jung, W. F. Steiner, instrument-makers, and J. G. Lorz, assistant 

 instrument-maker. Mr. Huff has been engaged, in addition to his 

 foundry work, chiefly on the design and construction of the apparatus 

 required in the Division of Experimental Work. Mr. Jung has 

 worked chiefly on the sine galvanometer, under Dr. Barnett's direction, 

 and on the marine earth-inductor improvements. Messrs. Steiner 

 and Lorz have done the bulk of the reconstruction work on magnetic 

 instruments and on the redesign and improvement of the marine 

 galvanometer and design and construction of the harmonic-motion 

 apparatus. 



