32 
109675.0 
x? 
and also the axes of the system to which it refers. By a fine divi- 
sion with vernier it is possible to determine the first four figures of 
the oscillation frequencies expressed in five figures (10° A—1, À expres- 
sed in AU). 
It deserves notice that also Ryppere has designed his curve by 
means of one model. He says’): “Toutes les courbes ont été tirées 
a l'aide du même calibre”. 
This model has proved to be a great help in detecting new 
series for elements for which no series had been observed up to now. 
For this investigation I have first chosen the spectra of those ele- 
ments for which Kayser and Runrar®) had found “eine andere Art 
der Gesetzmassigkeit”. Kayser points out already there that when 
we pass from one MENDELEJEFF group to the next, the series move 
to the region of the small wave-lengths. He says*): “Es ist also recht 
gut möglich, dass fiir weitere Elemente, die Serien im unzugäng- 
lichen Gebiet der Schumannschen Strahlen liegen’’. 
From what I have found, the results of which for Tin and Anti- 
mony I communicate here (I hope to publish the results for the 
other three elements Pb, As, and Bi later) I think 1 may infer 
that in general this conclusion is correct, but that the beginning of 
a great number of series is found in the already investigated region. 
Whereas for the other elements the finding of series was facilitated, 
because the parts where the lines converge, had been observed, while 
later the first terms were added by the discoveries of PAscHeN and 
others in the ultra red, exactly the opposite takes place for the 
elements considered here. The initial terms have been observed, and 
they lie together of all kinds of series; the part where the series 
begin to converge clearly lies outside the region of observation. So 
the difficulty was to accomplish the discovery of the series from the 
few terms that have only been observed of most of these series. 
Only very few observations on the ZeemMan-effect for Tin and Antimony 
have been made, so that at present they do not yet afford sufficient 
data for the finding of series. It would be desirable that investigations 
for these elements on the magnetical splitting up of the spectral 
lines lying more in the ultra violet were carried out. They might 
throw more light on the series found by me. So as these data were 
1) Kon. Svensk Vetensk. Akad. Hand. Vol. 23 p. 152. 1890. 
2) Ueber die Spektren der Elemente VII. Abh. Berl, Akad. 1894. Cf. also 
Kayser. Handbuch der Spektroskopie. Vol. lI, p. 578 et seq. 
ae. ip. oie. 
