300 PROCEEDINGS OF THE A3IERICAN ACADEMY. 



Eder and Valenta may have used small wires in the discharge circuit 

 of the condenser and so have introduced ohmic resistance. 



Influence of Results upon the Mapping of Spark Spectra 

 and upon Stellar Line of Sight Work. 



The bearing of the above results upon radial velocity investigations 

 in which a titanium spark is employed to give the comparison spectrum 

 is such as to emphasize the fact that low-energy and non-disruptive 

 conditions should be employed if the lines of the resultant spectra are 

 assumed to be severally of the same wave-length as those of the arc or 

 the absorption and bright lines of the stars. Furthermore, if a highly 

 disruptive spark be used, the same circuit conditions should be employed 

 at all times in any one observatory, to make the plates there taken 

 mutually comparable ; or, finally, the same conditions should prevail at 

 all observatories if mutually consistent results are desired. 



The general bearing upon the mapping of spark spectra may be seen 

 in the fact that an agreement between the wave-lengths of spark lines as 

 measured by various investigators is impossible unless the conditions 

 of the electric circuit be the same in all cases. 



In conclusion, I wish to acknowledge my indebtedness to the Rumford 

 Committee for the two grants which made this work possible, and to 

 Professors Hale and Frost of the Yerkes Observatory for the loan of the 

 grating used. I am also under obligation to Dr. George S. Isham for 

 the gift of the filar micrometer, and to Mr. Cornelius Vanderbilt for 

 generous financial aid. My assistants, Messrs. Hartley and Miller, have 

 proved invaluable at various times ; and to Mr. Boord I am indebted 

 for the analysis of the brass wire. 



Wabash College, Crawfordsville, Indiana, 

 June, 1905. 



