200 
hundred million tons, and, on a moderate estimate, 
this would require some ten million tons of meteoric 
iron to be accounted for. Mr. Thomson advances 
many arguments, and evidently concludes that the 
crater was produced by a meteoric fall. To account 
for the non-discovery of the main mass, he suggests 
that, as the meteor would probably not fall vertic- 
ally, bore-holes should be made under the southern 
and south-western walls of the crater where the strata 
are peculiarly disturbed; the twenty-eight bore-holes 
already made have all been near the centre and have 
revealed undisturbed sandstone at a depth of 850 ft. 
below the crater bottom. 
NOVA. GEMINORUM NO. 
aR HE brightness of Nova Geminorum would appear 
to have reached that stage when further diminu- 
tion is very slow but steady. On Friday last at 
8.45 p-m. an observation made in a 4-inch finder 
showed the nova to be but a shade brighter than the 
neighbouring star 984, of which the magnitude is 
given variously between 68 and 7 
By the courtesy of Father teats we have been 
permitted to examine four excellent spectrograms of 
the nova, secured by him at the Madrid Observatory 
on March 17, 19, 22, and 24 respectively, and trans- 
mitted to Nature. 
2 
le 
NOVA GEMINORUM MADRID 
NOVA RERSE! MAR 3 ie = = KENSINGTON — 
Bs apne : a 
™ an 2 Mong = oe 
: Bas a 
| ae ae =— 
|  Ennancer ENHANCED Fe 
{ tROW Lincs LINES 
Father Iniguez reports that between March 16 and 
April 10 the spectrum underwent important modifi- 
cations, of which he especially mentions the changes 
in the structure of the hydrogen lines, the almost total 
disappearance of the bright calcium radiation, Kk, 
since March 20, and the marked diminution of the 
ultra-violet part of the spectrum. The principal radia- 
tions are those of hydrogen, each bright band being 
accompanied by the usual well-marked dark band on 
its more refrangible edge; during the last days of 
March the more refrangible bright hydrogen bands 
became relatively weaker, He becoming much weaker, 
relatively, than H8 and Hy, while the bright H¢ 
nearly disappeared. 
In addition to the bright lines there are numerous 
dark lines, especially between HS& and Hy, which 
Father Ifiguez describes as absorption bands, and 
among which he recognises the helium lines at 
AA4026, 4144, 4388, and 4472, and the spark line of 
magnesium at A4481. He also directs attention to 
the apparent separation of the bright and dark 
hydrogen lines which attained its maximum between 
March 22 and 24; the apparition of a bright line 
traversing the dark companions gave the hydrogen 
pairs an appearance of duplication which, we believe, 
has also been recorded at the Cambridge Observatory. 
Father Ifiguez states that considerable variation 
in the number, intensity, and definition of the 
numerous bright and dark lines has been very notice- 
able. From March 22, when a magnificent spectrum 
NO. 2217, VOL. 89] 
NATURE 
[APRIL 25, 1912 
was photographed, the lines became more prominent 
and also became more uniform inter se, more par- 
ticularly between H8 and Hy; generally speaking, the 
dark lines are relatively diffuse and ill-defined. 
A recrudescence of activity in the star was observed 
on March 23-25, since when the nova has gradually 
decreased in brightness. The increase of redness con- 
temporaneous with the decrease in the intensity of 
the ultra-violet spectrum is remarked upon by Father 
Ifiguez, who further discusses his spectra in No. 16 
of the Comptes rendus. 
For the purpose of comparison we reproduce two of 
Father Ifiguez’s spectrograms, taken on March 19 
and 22 respectively, alongside a spectrum of Nova 
Persei photographed at South Kensington on March 
3, Igor. It will readily be recognised that although 
there are important differences in the minor details, 
the two spectra are, in general, very similar; conse- 
quently the explanations of the chemical origins of 
the lines in Nova Persei given by Sir Norman Lock- 
yer in 1go1 hold good, generally, for those in the 
spectra of Nova Geminorum. In that paper it was 
shown that the chief bright lines other than hydrogen 
could be adequately represented by the principal en- 
hanced lines of iron, and, in a less degree, of other 
metals. 
Comparing the 
crease of the bright calcium radiation, 
March 19 and 22 is very readily discerned. 
Madrid spectra, the abnormal de- 
K, between 
Attention 
seg 
should also be directed to the apparent reversal of the 
| dark hydrogen lines, especially noticeable in Hy on 
| March 22, which is evidence in favour of these dark 
_ bands, at least, being true absorption phenomena. 
While the comparison shows that the spectra of 
the two nove are in general very similar, there are 
differences in the details, as is shown in the subjoined 
description by Mr. F. E. Baxandall, based upon a 
careful examination and discussion of the several 
photographs at the Solar Physics Observatory :— 
Spectra of Nova Geminorum. 
A comparison of the excellent spectra of Nova 
Geminorum obtained on March 19 and 22, by Father 
Iniguez, of the Madrid Observatory, with that of 
Nova Persei photographed at Kensington on March 
3, 1901, shows that in the main features the spectra 
of the two nove are the same. The well-marked 
bright hydrogen lines in Nova Geminorum are accom- 
panied by strong absorption lines on the more re- 
frangible side, and the isolated bright bands between 
Hy and H5 typical of novee spectra are present. The 
Nova Persei band at A4130, probably due to proto- 
aap frA4128'2 4 P e 2 ; 
| silicum 4 A130 | and identical with the conspicuous 
double line in such stars as @ Cygni, Rigel, and 
Sirius, is either lacking in Nova Geminorum or occurs 
only very faintly. 
Between Hy and HB8 the spectra show the usual 
complex set of bright lines seen in previous nove. 
