684 



Prof. R. VV. Wood on Resonance Spectra of 



were determined from photographs made with the three- 

 prism spectrograph , as I have not yet obtained a record of 

 them with the grating. The values can be considered correct 

 to two or three tenths of an Angstrom unit I think, and 

 represent the position of the centres of the doublets, for the 

 prism spectrograph barely resolved them. 



I have used only the first members of the doublets in 

 calculating the wave-length differences, frequencies, &c. 



Doublet series excited by green Hg line 

 (Cooper-Hewitt lamp). 





Dif. 



Frequencies. 



Freq.-Dif. 



7005-5* 



6909-5* 



68210* 



6732-4* 



66450* ? 



6560-7* 



91 



88-5 

 88-6 

 87-4 

 84-3 



142850 

 144730 

 146610 

 148540 

 150490 

 152420 



1880 

 1880 

 1930 

 1950 

 1930 



6558 4 

 Missing 



82-2 





1960 



6396-30 





156340 



1970 



6394-3 



79*66 





6316-64 





158310 



2010 



6314-4 



7905 





6237-59 





160320 



2000 



6235-7 



76-92 





616067 





162320 





6158-8 

 Missing 



74-94 





2025 



6010-79 





166370 



2040 



6009-1 



72-85 





5937-94 





168410 



2070 



59350 



7206 





5865-88 





170480 



2050 



5864-8 



69 77 





5796-11 





172530 



2090 



5794-6 



69-28 





5726-83 





174620 



2090 



5725-3 



67-86 





5658-97 





176710 



2113 



5657-4 



66-90 





559207 





178823 



2107 



5589*8 



65-17 





5526-90 





180930 



2195 



5525-2 



66-16 





5460-74 (Hg) 



183125 



2158 



5397-13 



63-31 



185283 



534263 

 533763 



59-50 



187350 



2067 



The last two lines form a wide doublet, and are very faint: 

 they appeared on only one plate, and I am not sure about 

 fitting them into the series. I have taken the second member 



