Hinrichs on Dark Lines in the Spectra of the Elements. 35 
Physical interval. 
Group I, d,=5-0 Ae 28 OD) 
“TI, d,=2°026 A,= 5d,=10'13] 
“TIL, dj= *75 A,=14d,=105 
“IV, d,=1'3 A,= 8d,=104 
. NY, ae A <=: 36s IOe 
“ VI, d,=23 A,= 4d,= 92 
5d,=11'2 
lengths being for this group considerable. The whole of the 
brilliant group III has been considered as A,, it forming deci- 
dedly a natural group. The great approximation of the values 
eee et wave-lengths will prove very nearly equal throughout. 
ut now we must farther compare not the range of a group but 
1e 
physical signification ; they may prove to be the only yet known 
members of less intense groups. 
Comparing the values of Kirchhoff’s scale with the well known 
wave-lengths of Fraunhofer’s principal lines, we found by a 
graphical interpolation the following reduction to wave-length 
for the various single lines or groups: 
K. Wave length Differences 
G.=0™-0042-914+ if d= 8. 
Group I, 2823 + 0-0 
ite + 2632 15tol'9 — 20—1 or +3 
6c, 2058°0 57 73 
2c, 18328 7-4 904-2 
56, 1627-2 89 1104-1 
“ «1588 96to9S 120 
2b, 1443-5 5 41 
“ TV, 1238 12°8 163 
1029-3 15°4 195-.-2 
V, 825 19°7 250 —-3 
“ VI, 742 22:3 285 —-] 
