360 
PROF. A. FOWLER AND MR. C. C. L. GREGORY ON THE ULTRA-VIOLET 
features. In each case there are several superposed series, and some of the lines, 
which are probably unresolved composites, have to be assigned to two or more series. 
The probable series belonging to the secondary maximum have been designated a 1} a 2 , 
a 3 , and « 4 ; those on the red side of the chief maximum b l and b 2 ; and those on the 
more refrangible side of the chief maximum c l5 c 2 , and c 3 . There is some uncertainty 
as to the c series, as alternative arrangements of the lines appear to be consistent with 
series relationships. 
The lines belonging to the various series are indicated in the general table, but a 
clearer idea of their character may be obtained from fig. 3, where the series are plotted 
to scale. The complete spectrum is first shown, with lines of lengths proportional to 
the intensities, and below these are drawn the separate series. It will be seen that a 
large proportion of the band lines fall into the nine series, and it is quite probable 
that all of them could be assigned to series if it were possible to employ still greater 
337 
338 
0 
"'1 v f r m' ii[p tii"' 1 
'T| 
T" 
—0] 
z 
1 M | M 
cl y 
~Tt 
A 
'|~i ' 1 | 
a y 
r TT T T r 
I 1_1_I!1_L 
1 i 
_ 
<, 
1 
1 1 
1 
>' ' 
1 
1 i 1 
1 
336 
7 8 9 0 
-1.1 L.—.. ■■ i . . . .. J , . L . . .1 1-1 
i 
2 
j_ i — 
3 4 
.1 ■ 1 .. .1 
6 
.. . 1 
6 7 8 
1 '1_t - 
h 
UF 
i i l l f 
TTTT 
S? 
1111111 | 1 , 1 , 1 , 1 , 1 r 
c ii 
Fig. 3. Resolution of the central and secondary maxima into series. 
resolving power. It will suffice to give numerical data for as a further indication 
of the characteristics of the series involved in the central maximum. These are 
shown in Table III. 
The series is closely represented by the formula— 
v = 297 55'176 — 0'6935m+ 0'03327m 2 —0'008326m 3 . 
where m has values ranging from 3 to 21. The greatest deviation in wave-number is 
0'41, corresponding to a difference of 0'045A between the observed and calculated 
values. The differences between the observed and calculated wave-numbers are shown 
in the last column of the table, and it will be seen that they are sufficiently systematic 
to indicate the imperfection of the formula. There would be no difficulty in calculating 
such foi’mulee for the other series, but it is not clear that they would serve any 
immediately useful purpose. 
