38 Hinrichs on Dark Lines in the Spectra of the Elements. 
thus having the simple ratio 3: 4:1, and giving the physical — 
difference 4, =7d.=5'6. a 
Group Il, dy, A 1d $4 
L K. D. 
t C. E. is 
4d  —-: 1387-0 aie ‘ 874 +} “4 
6c 43°5 ie a 438 +4 8 
5d 511 hig : $8 et 
5b 52°7 is is $46. 4 41 
5b 62:9 i ‘ 630 +1 
6d 67-0 pi 7 67-0 0-0 
5b 72°6 “jhe ‘ss 72°6 0-0 
4e 80°5 aye : 806 +1 
4c 84:7 “7 6 846 - ‘1 
6c 89°4 ta 5 89-4 0-0 
5d 90°9 re 91:0 - A 
5 97-5 oi ‘ 974 = 
4¢ 1401°6 ae > i0l4 ~— 2 
4c 10°5 aie 14 102 = 38 
6c 21°5 nee > 14. — 1 
5b 23-0 ne ‘ 23-0 0-0 
5b 25-4 a : 25°4 0-0 
5b 28-2* 278 8 et 
As starting point for C we made E=0 for the principal lines in © 
the eaiddle of the group, i.e., Bi: 6d; and 89, 6c. Around these # 
lines E are very small, but o e extremity SE is positive, onthe 
other negative: thus Piaay | indicating that the greater values 
of E are due to the great range—almost 100 mm. K—of the ~ 
up, a range so great that the wave-lengths can not through- 
out fuily ¢ correspond to the yalues K on Kirchhoff’s scale. 
As to the intervals, they again seem at first sight ‘to be very 
eapricious; yet w e find 
a, observed, 82.9.522512:62.72102526:2:8: 5:02:14: 9:32.28 
ye Nerensacinapaetionetel 
——— 
nae mere 
physical, 17 : My : 22 pat Ee Sie? ee 
or, 2A,-+-3d, : 24, : 84,44, SA, «7 OA, FeAl TAL ee 
the extremities of “which series may be adjusted by extending 
the observation, thus givin 
Sdy-+ 2A, : 2A ie a oe > 24,:24,:4,+44,, 
@ symmetrical series of 74,, on each side of the mann d,, and 
oo the left 3d,, on the right 4, +d, or 8d,; yet it may be that 
further ebservations will pt et the eens ingerval 22d, to 21d, 
and thereby simplify the series. We m t accept the observa- 
tions at hand, and these show that 4, ="d, is the physical dif- 
ference of this group, and that these divisions of higher order 
are erin on le, symmetric in regard to the middle of the whole 
cing aia that not boul A4,=A,, as ought to be, 
joi — 
ve Fe 
