Mr Baxandall, On Lines of Magnesium in Stellar Spectra. 323 
On the Presence of certain Lines of Magnesium in Stellar 
Spectra. By F. E. Baxanpatt, A.R.C.Sc. (Communicated by 
Professor Newall.) 
[Read 24 November 1913] 
IN a recent paper* by Professor Fowler on “New Series of 
Lines in the Spark Spectrum of Magnesium,” four magnesium 
spark lies are recorded which do not belong to the series. The 
same four lines had previously been given by Fowler and Paynt, 
but in the later paper more accurate wave-lengths are given. 
The series lines, with the exception of \ 4481°3, are outside the 
region usually obtained in photographs of stellar spectra, but the 
four lines mentioned occur in a part of the spectrum available for 
investigation, their wave-lengths being 4384'86, 4390°80, 4428-20 
and 4434-20. In a “Catalogue of 470 of the Brighter Stars,” pub- 
lished in 1902 by the Solar Physics Committee, a record is given 
of the wave-lengths of lines in the spectra of various stellar types. 
Reference to this shows that weak lines are recorded at or near 
the positions of Fowler's magnesium lines in the spectra of a Cygni 
and a Canis Majoris, as follows: 
Mg. Spark 
Lines (Fowler) a Cygni - a Canis Majoris Remarks 
4384-86 — 4384-7 (1) 
4390°80 4391-0 (2°3) 4391-0 (2) Stellar line probably chiefly due 
to proto-titanium 4391-19. 
4428-20 4428-7(1) 4428-7 (1) 
443420 4434:4(1) 4434-4 (<1) 
Although the magnesium line 4390°80 may enter into the 
composition of the stellar line 4391-0, the latter is probably due 
chiefly to proto-titanium line 4391-19, as all the other prominent 
enhanced lines of titanium are represented in these stellar spectra. 
The remaining lines have not hitherto been assigned to a terrestrial 
source, and it seems highly probable that they are the stellar 
analogues of the magnesium lines. The largest divergence in 
wave-length is 0°5 tenth-metre (line 4428-20), but there is a 
possibility of such an error occurring in the measurement of weak 
stellar lines which, under the magnification used in the measuring 
instrument, are very difficult to see. 
Since the publication of the stellar records referred to, better 
photographs of the spectra have been obtained at South Kensing- 
ton, and new measures of the wave-lengths of the lines have been 
made, The fiducial lines used in the determination of the posi- 
tions are Fe 4383°72, pFe 4417-00 and pTi 4444-0, all of which are 
* Proc. Roy. Soc. vol. uxxxix. p, 133, 1913. + ib, vol, LXxII, pp. 253—257, 
VOL. XVII. PT. IV, 22 
