January 18, 1917] 
with sodium sulphate, because it is cheaper.” There 
is no reference to the consequent modification of the 
entire scheme in terms of the main product (cellulose) | 
and of the offensively malodorous volatile by-products. 
To the main report is appended one by Mr. D. C. 
Winterbottom on ‘‘Supplies and Cost of Raising 
* Marine Fibre,’’’ the remarkable product of Posidonia 
australis, 
more than one “promotion” has been attempted; 
according to the author, two of-these survive, of which 
the Posidonia Fibres Syndicate is producing “six to 
seven tons per week at Port Broughton. On his esti- 
mate of the costs of dredging, etc. (ql. 10s. 6d.), and 
subsequent handling, the clean; air-dry fibre cannot 
be produced to sell at less than 17l. per ton. A second 
appendix, by Mr. J. C. Earl, on the paper-making 
value of various South Australian raw materials, 
. deals with six indigenous products of little promise. 
War problems and after-the-war problems are dis- 
cussed by writers of every varying shade of opinion in 
Scientia, the Italian equivalent of our own Science Pro- 
gress, but which exhibits a more international tend- 
ency by publishing French translations of English and 
Italian articles. Thus Prof. Sayce (xix., 5) considers 
that the history of the Assyrian empire under Tiglath 
Pileser and his successors affords a lesson as to what 
may be expected from a military nation imbued with 
the spirit of world-conquest. In the same number 
Prof. Roberto Michels, of Turin and Bale, deals with 
- the demolition of the international labour movement. 
Prof. Knut Wicksell (Lund, Sweden) discusses the 
influence of over-population in stimulating wars, and 
expresses the somewhat sanguine prophecy that with 
the present decline of the birth-rate in European coun- 
tries peace conditions may become more possible (xix., 
6). Prof. A. Pillet, of Paris (xx., 12), considers that 
the problem of the war from the Allies’ point of view 
involves the entire crushing of the German Empire. 
Peace conditions and what is to happen after the war 
form the subject of speculations at the hands of Prof. 
E. Catellani, Padua (xx., 8),.and E. Cecotti, Messina 
(xx., 6). Sir Alfred Hopkinson (xx., 12), while em- 
phasising the strict adherence to the principles of inter- 
national. law in the operations of the Allies, blames 
the neutral countries for not taking action in enforcing 
‘the observance of similar principles on the enemy. 
But an attempt is made to apply the methods of exact 
science to the problem of when and what offers of 
peace should be made by a victorious belligerent, in 
a paper on ‘‘The Economic Dynamics of War,” by 
Prof. John Bates Clark, of Columbia University. In 
his opinion the time for making the offer is when 
the gain to be derived from continuing the war is 
more than outbalanced by the sacrifice required for 
its continuance. And the terms to be exacted from 
the vanquished side should consist of all that the 
prospective victor could gain by pushing his conquest 
to the bitter end minus the cost of so pushing it. If 
these terms are offered and can be secured: there is no 
advantage for either side to continue the struggle. 
Tue Open Court Company will publish very shortly 
a translation, from the first ‘edition, of ‘‘The Geo- 
metrical Lectures of Isaac Barrow.” The work will 
contain a portrait of Barrow, and an introduction and 
notes by J. M. Child. 
OUR ASTRONOMICAL COLUMN. 
Avrora Boreatis.—Mr. Denning writes that though 
the moon was nearly full on the evening of January 4 
there was a brilliant occurrence of aurora observed 
from widely distant stations. The Rev. W. F. A. 
Ellison observed it from Fethard-on-Sea, near Water- 
NO. 2464, VOL. 98] ° 
NATURE 
For the industrial utilisation of this product 
397 
ford, and describes it as a particularly magnificent 
display. From Edinburgh, at about 1o p.m., there 
was also a fine exhibition, extending along a consider- 
able range of the northern horizon. Rapid variations 
were apparent in the details, the light alternately ap- 
pearing and disappearing. Clouds were very prevalent 
at low altitudes in the northern region, and the glow 
spread upwards from behind these with striking effect. 
At Bristol there was an auroral glow between about 
8 and 9 p.m., and at 8.30 a bright streamer shot up- 
wards to about 15° W. of the Pole star. But the appear- 
ance was rendered somewhat inconspicuous by the 
unusual brilliancy of the moon, due to the very clear 
atmosphere. 
Dr. A. A. Rambaut, Radcliffe Observatory, Oxford, 
sends us the following notes of observations of this 
aurora made by Mr. W. H. Robinson at that observa- 
tory, and also of the bright meteor of the same date, 
referred to in last week’s Nature (p. 379) :—A bright 
haze in the northern sky attracted considerable atten- 
tion at Oxford soon after $8 p.m. on January 
4. A long segment of an auroral arch lay 
along the horizon, with its apex at a small 
altitude in the N.N.W. Isolated streamers ap- 
peared, but generally for a few seconds only. The 
finest display occurred at 10.15 p.m. (or perhaps a 
minute or so later), when streamers suddenly developed 
all along the arch, lasting for a very brief interval, a 
white haze taking its place. At about 10.15 p.m. a 
brilliant fireball attracted notice, which ran rapidly 
downwards from the direction of the moon, passed 2° 
or 3° east of Jupiter, and burst, with a blue colour, 
10° or 15° below the planet, its trail swiftly disappear- 
ing. The light of the meteor was distinctly more 
intense than that of the moon. An approximate esti- 
mate places the track from 3h. om., +18° (first seen), 
to oh. 45m., +5°. 
Cioups on Mars.—In the course of a report on the 
planet Mars, in which observations made by members 
of an international organisation are summarised and 
compared, Prof. W. H. Pickering makes several in- 
teresting references to clouds which appeared on the 
planet during the opposition of last year (Popular 
Astronomy, vol. xxiv., p. 639). Clouds were seen 
frequently by all the observers, and Prof. Pickering 
points out that the clouds always lie over the so-called 
desert regions of the planet, apparently being precipi- 
tated so soon as the fertile regions are reached. Dis- 
solution is sometimes very rapid. Only a few years 
ago it was claimed by some observers that clouds were 
rarely or never to be seen on Mars, but during the last 
opposition the planet was scarcely ever seen without 
them. The existence of clouds in the atmosphere of 
Mars appears to have been first established by Sir 
Norman Lockyer in his observations during the opposi- 
tion of 1862. 
Tue CEPpHEID VARIABLES.—The results of some fur- 
ther investigations of the relations between the orbital 
elements of Cepheid stars have been given by Dr. 
Ludendorff (Astronomische Nachrichten, No. 4869). He 
finds that for several stars resembling 6 Cephei, the 
elements are closely related, as shown in the formula 
100¢ cos w= — 21°8 +.0°963(1 — e2)§K3P. 1073, 
where e, w, P are respectively the eccentricity, angle 
from periastron to node, and the period in days, while 
K is half the total amplitude of the radial velocity. 
A similar formula is applicable to stars resembling 
¢ Geminorum, the two numbers on the right-hand side 
of the equation then becoming +2-4 and +0-73. Fur- 
ther confirmation has been obtained of the relation 
previously given by Dr. Ludendorff, 2K=47-3 A, where 
A is the range of variation im brightness expressed in 
magnitudes; this, however, appears to be valid only 
for stars of types F. to G. ; 
