74 



Intelligence and Miscellaneous Articles. 



current from a storage-battery. A review of all the spark spec- 

 trum-lines has been made with the arc, and a few lines added to 

 those that the spark gave. A steam- jet* was employed to increase 

 the luminosity of the spark. The work has been confined to the 

 lower portion of the spectrum, where it still appears that eye- 

 observations have advantages of the photographs. 



The position of a metallic line is determined by bringing the 

 crosswire of the micrometer upon it, letting in the sunlight, and 

 moving the crosswire to one of the standard lines of Rowland's 

 tables. The true wave-length of the metallic line can then be 

 computed from a previously determined micrometer-constant. As 

 a check to the result so obtained the metallic line has been inter- 

 polated, with the micrometer, between two of the standard lines 

 in the same field of view, and the whole process has been repeated 

 on different days until it became assured that positions of the me- 

 tallic lines were as precise as those of the standard lines themselves. 



Copper Spectrum. 



The subjoined table gives the results as obtained for the spectrum 

 of copper. The first two columns contain respectively the wave- 

 lengths and intensities as given by Thai en ; the third, the wave- 

 lengths as determined in the present work. 



6379-7 



2 



6380-899 



6218-3 



5 





5781-3 



2 



5782 : 285 



5700-4 



1 



5700-442 



5535-64 



5555-119 



5292-0 



2 



5292-68 



52171 



1 



5218-308 



5152-6 



1 



5153-345 



5104-9 



1 



5105-663 



5011-4 



4 







5016*86 



4955-5 



3 

 3 





4932-5 



4933- 181 



Copper Spectrum. 



Thalen X. Corrected X. 



Eemarks. 



Surrounded by continuous spectrum. 



No line seen. 



Reversed in arc. Reversed in sun. 



Reversed in arc. Reversed in sun. 



Reversed in sun. Seen only in the arc 



Seen only in the arc. 



Reversed in sun. 



Reversed in arc. Reversed in sun. 



Reversed in arc. Reversed in sun. 



Reversed in sun. 



No line seen. 



Seen only in the arc. 



No line seen. 



Reversed in sun. 



Reversed in sun. 



Zinc Spectrum. 



The examination of the zinc spectrum is here limited to five 

 lines ; many of the remaining lines being mere dots close to the 

 poles of the metal, others very broad and nebulous, and in general 

 too ill defined to admit of measurement with the apparatus em- 

 ployed. In strong contrast to the remaining lines these five are 

 very bright and sharp, and may be called the representative lines 

 of the metal within those limits. 



* Silliman's American Journal, Feb. 1889; Phil. Mag. Feb. 1889. 



