ApriL 7, 1904] 
~*‘ perturbative function,’’ and gives the elements, step by 
step, for the determination of the orbit of (334). 
ABSORPTION IN THE SOLAR ATMOSPHERE.—In an article 
published in No. 2, vol. xix., of the Astrophysical Journal, 
Mr. Frank W. Very discusses the cause which produces the 
<apparent selective absorption of the more refrangible radi- 
ations emitted by the photosphere which takes place in the 
solar atmosphere. He points out that beyond certain limits 
the increased depth of an ** emission ’’ layer does not in- 
crease the radiating power owing to the fact that beyond 
these limits the increased emission is counterbalanced by 
the increased absorption in the outer layers; similarly the 
line absorption produced by a gas does not increase in- 
definitely with the depth. 
the absorbing atmosphere is everywhere deeper than is 
-actually essential to produce the absorption observed, and 
consequently it makes little or no difference whether the 
‘emission and absorption take place at the centre or the 
edge of the solar disc. Mr. Very contends that the apparent 
selective absorption is due to “ selective scattering ’’ rather 
than to ‘* absorption,’’ the more refrangible radiations being 
scattered and reflected by the small particles which float 
about in the solar atmosphere; further, he thinks that the 
scattering does not take place solely in a thin laver immedi- 
ately above the photosphere, but is active even in the ‘imits 
-of the outer corona. Whereas “‘ absorption ’’ would require 
that the absorbing medium should become heated 
“*‘ selective scattering ’’ does not, for the radiations are 
simply reflected. 
This theory explains the nearly constant radiations of 
sun-spots when nearing the limb by supposing that spots, 
‘being cooler than the photosphere, only emit, at any time, 
the less refrangible radiations which are not affected by the 
extremely fine particles that cause the scattering. 
iw 
Wave-LENGTH OF THE GREEN CapmiuM Line.—It has been 
noticed by many spectroscopists who are interested in the 
sdetermination of absolute wave-lengths that the wave-length 
of the green cadmium line at A 5086 as determined by M. 
Hamy (Comptes rendus, No. 130, p. 490, 1900) differs con- 
‘siderably from the value obtained for the same line by 
MM. Michelson and Benoit. This discrepancy is now 
accounted for by M. Ch. Fabry, who shows that under the 
conditions obtained by Michelson in a tube of cadmium 
vapour with electrodes the line is a close doublet, whereas 
‘in the tube used by Hamy without electrodes it is a triplet, 
-and the latter observer measured the less refrangible com- 
ponent which does not appear under the former conditions. 
M. Fabry has determined the interval between the com- 
ponent measured by Michelson and the extra line measured 
‘by Hamy, and has found that on taking the value of this 
‘interval into account the apparent discrepancy is reduced 
from 15 in 1,000,000 to 3 in 10,000,000 (Astrophysical 
_Journal, No. 2, vol. xix.). 
A Bricgut Meteor.—Mr. Roland Mott writes to say that 
‘on March 22 he observed a bright meteor from a position 
four miles west of Gloucester. ‘* The meteor was in the 
north-eastern sky, and first appeared at an altitude of about 
45 degrees from the horizon, falling directly towards the 
earth. It had the appearance of a brilliant arc lamp, and 
far outshone the stars of the Great Bear, although they and 
tthe moon were very bright. The time was 9.58 p.m.” 
SpectRA OF Mrixep Gases.—From a number of experi- 
ments made in order to ascertain the reason of the pre- 
‘dominance of one spectrum over another in a mixture of 
gases, Mr. P. G. Nutting, of the National Bureau of 
Standards, Washington, has arrived at the definite con- 
clusion that at such low pressures (0-1 to 10 mm.) as obtain 
in a Plucker tube, and under a homogeneous excitation 
-of not more than 1o milliamperes, ‘‘ the spectrum of a gas 
of greater atomic weight will be the brighter.’’ 
During his experiments he has found that neither the 
relative quantities nor the metallic or non-metallic character 
of the vapours present affect this result. The introduction 
of one molecule of mercury into three thousand molecules 
of hydrogen will reduce the brightness of the hydrogen 
spectrum at least one half, and sulphur and iodine (non- 
metals) are nearly as effective in causing this reduction as 
is mercury. 
About eighty combinations of the fifteen readily vapour- 
NO. 1797, VOL. 69] 
NATURE 
For this reason he believes that | 
543 
| 
| isable elements have been studied, and it is hoped to extend 
| the results by using quartz tubes in which even copper and 
| silver may be vapourised. 
In concluding his communication Mr. Nutting discusses 
the effects of chemical combination on these results, and 
the explanation of the latter afforded by the modern electron 
theory (Astrophysical Journal, Np. 2, vol. xix.). 
RETURN OF THE NATIONAL ANTARCTIC 
EXPEDITION. 
HE Discovery, with the members of the National 
Antarctic Expedition on board, arrived at Lyttelton, 
New Zealand, on April 1, accompanied by the relief ships 
Morning and Terra Nova. The news of the safe return of 
the expedition has been received with satisfaction ; and there 
is every reason to believe that the scientific results obtained 
| will make the expedition a noteworthy one in the records 
of polar exploration. 
The Discovery left England in the summer of 1901 and 
reached Lyttelton on November 23 of that year. A few 
| weeks later the vessel sailed for the Antarctic, and the first 
news of the work accomplished was brought back by the 
relief vessel Morning in March of last year (NatuRE, vol. 
Ixvii. p. 516). It was evident from the information then 
received that the expedition had already achieved great 
success both as regards exploration and scientific obsery- 
ation, but some anxiety was felt as to the chances of the 
Discovery being released from the ice during the southern 
summer just passed. When the winter quarters of the 
Discovery were found, the ice prevented the Morning from 
approaching the vessel to a less distance than eight miles ; 
and the transfer of coal and provisions had to be done by 
means of sledges. As the Discovery only had provisions 
to last until January of this year, it was considered necessary 
to send out two vessels to relieve the expedition and bring 
back the members if the ship could not get free. The 
Morning and Terra Nova were therefore equipped for this 
purpose, and sailed from Hobart on December 5, 1903, and 
reached the edge of the ice on January 5 of this year. There 
were then seventeen miles of ice between the Discovery and 
the sea, but heavy weather and explosives assisted this to 
break up, and in the middle of February the vessel was in 
open water. 
Commander Scott’s report upon the results of the first 
year’s work in the Antarctic was summarised in NaTuRE 
of July 30, 1903 (vol. Ixviii. p. 307); but some additional 
details of interest are given in Press messages from New 
Zealand. A Reuter message states that the interior of 
Victoria Land is found to rise to a height of gooo feet, and 
is evidently a vast continental plateau, 
Wilkes Land was found to be non-existent, the Discovery 
sailing over the region where it has been charted. Since 
Ross’s time, the ice is alleged to have broken back 30 
miles from the barrier, which is moving northward at the 
rate of a quarter of a mile a vear. 
The main practical interest of the expedition lies in the 
results of the magnetic investigations. Continuous observ- 
ations were taken in the neighbourhood of the magnetic 
Pole. 
One primitive form of insect life was secured, and much 
information obtained as to the higher forms of animal life. 
The latter consisted mostly of birds, including the emperor 
penguin, specimens of which have not previously been found 
| in these regions. The only species of living plants secured 
were mosses and lichens, but sandstone fossil remains of 
dicotyledonous plants from an altitude of Sooo feet were 
obtained on a sledging trip westward. 
The following particulars of the expedition are from an 
interview which the correspondent of the Daily Mail at 
Christchurch, New Zealand, had with Commander Scott, 
published in that journal on Saturday last. 
All went well after the departure of the Morning in 1903. 
The ice remained fast and firm within four miles of the 
Discovery. The weather was colder but less windy than 
in 1902. One hundred degrees of frost were recorded in 
May. The routine of scientific work and observations con- 
tinued as in the previous year. 
Sledging opened in September under the most severe 
| conditions. One party made a depot to the south; another 
