258 CARNEGIE INSTITUTION OF WASHINGTON. 



(3) Several instances showing the close relation between the Stark 

 effect and the broadening of lines in arc and spark spectra were observed. 



(4) In the spectra of copper and silver a number of detached com- 

 ponents and isolated lines close to the series lines were found, which 

 have the peculiar property of showing themselves only in a strong 

 electric field. 



In March 1919, the grating spectrograph used for the Stark effect by 

 Mr. Anderson and by Mr. Takamine was taken down in order to have 

 the optical parts fitted into a new metal mounting constructed in the 

 machine-shop. While this was being done, Mr. Anderson studied the 

 Stark effect in the region X 2200-X 3600, using the large Fuess quartz 

 spectrograph, the prism of which was refigured in order to improve 

 the definition. About 60 spectrograms were obtained with this instru- 

 ment for the metals already studied in the visible region by Anderson 

 and Takamine. In most of this work rectified alternating current 

 from a small high-potential transformer was used instead of direct 

 current from the set of dynamos, as this was found easier to work with, 

 and equally effective. 



The new metal mounting for the grating spectrograph was delivered 

 by the machine-shop about the middle of August, and as soon as data 

 for all of its adjustments are obtained a careful study of some of the 

 pecuHar Stark effects observed, especially for chromium, will be 

 undertaken. 



CONSTRUCTION DIVISION. 



DRAFTING AND DESIGN. 



The drafting department has been occupied mainly with the 100- 

 inch telescope and with work undertaken for the Signal Corps and 

 the Ordnance Department of the Army in connection with the war. 



New designs for the 100-inch telescope include compression rings 

 for the Newtonian and focal-plane cages required to give the cages 

 greater rigidity, revisions for the main observing platform and the 

 mirror elevator, an observing platform for use at the Cassegrain f o cus 

 numerous small parts and attachments, and a number of cases used 

 for housing equipment when not in use. 



The work done for the Signal Corps was experimental in character, 

 and such as to require many special drawings. For the Ordnance 

 Department designs were made for 13 machines used in the optical 

 work which was carried out under the direction of the Observatory. 



THE OPTICAL SHOP. 



Prior to April 1, the work of the Optical Shop was entirely devoted to 

 the requirements of the Ordnance Department of the Army, as described 

 in a separate report on the war sei-vice of the Observatory. Since 

 that date, the following optical parts have been figured: 17 plane and 



