584 DR J. HALM ON 
shorter band-series, fails to account for the phenomena if they extend over a wider 
interval. If this could be proved, the RypBeRG-THIELE equation would certainly lose 
much of its value from the theoretical point of view. But there is an alternative. It 
is quite possible that the Cyanogen-band discussed by Professor Kayser is not one 
single series, but really consists of several distinct parts apparently joined together so 
as to give the appearance of one continuous series. We have seen in the case of the 
Oxygen-band that two series of the same band need not necessarily exhibit their lines 
right down to their common head. It was noticed that while the one series which 
starts from the head may almost suddenly drop off on the tail side, the second series 
may show the inverse phenomenon, viz. a sudden decrease of intensity on the head-side. 
The effect of this peculiar behaviour is that the second series forms apparently the tail 
of the first series. Now in the Oxygen-bands both series consist of pairs of lines, but 
the distances between the components of the first (or head-) series are considerably 
smaller than those of the second (or tail-) series. Besides, in the head-series the distances 
decrease slightly towards the tail, while in the tail-series they increase very rapidly. 
To show this I subjoin a table giving Mr LEstrr’s wave-lengths of the B-group. 
First (Head-) Series. Second (Tail-) Series, First (Head-) Series, Second (Tail-) Series. 
HL SHES yy | ORE) 
io ojos | Milaa 
eo toe | Billa 
vos f 089 asge50 f O88 o6a8 | 272 
fie } me coon } 3100 
7349 f O96 04-36 p O24 
roa f O98 05°26 | 55 
HS fo ae 
7783 ¢ 0% 1438 | 493 
SF on Lat 
Pop } 0:92 aes 457 
Now let us suppose for a moment that the distances between the components are very 
much smaller, perhaps 5th only of those actually observed. ‘The effect is that the 
first series appears as a single-line band, while the second, with sufficient dispersion, 
may still show its double character. Near the point where the two series coalesce, we 
would then have the following wave-lengths of the centres of the lines: 
