* JuLY 3.71902 | 
NATURE 
223 
but the yellow, purple and pinkish tinges were most general. 
The sunsets of the 22nd and 26th and the sunrises of the 27th, 
28th and 29th were those which showed the salmon tint to the 
greatest advantage. 
In a letter to NATURE of last week, Mr. Krohn recorded 
some remarkable sunsets at Madeira, while a Dazly Mail 
correspondent at Bombay (June 29) writes :—‘‘The extra- 
ordinary red sunsets which have been witnessed for several 
days past are believed to be due to Martinique dust in the upper 
atmosphere.” 
There is little doubt, therefore, that the dust is on the move, 
being carried by the upper air currents, and perhaps we may 
yet observe more brilliant effects. 
WiiaM J. S. Lockyer. 
Solar Physics Observatory, June 30. 
As one of the first, in your pages, to call attention to the 
import of the sunset glows in 1883, I have additional interest 
in noting the recurrence of similar glows during the past few 
days. On three nights, at least, they have been more marked 
than any seen by me since the eighties. 
T observed the glow first on June 26, at Croydon, but it was noted 
at Street, Somerset, on the 24th (Tuesday last). I was there 
from the 27th to 29th, and saw glows each evening. On the 27th 
it was brighter, though less widely spread, than at Croydon on 
the 26th. But at Street, on the 26th, I am informed by my 
cousin, Mr. Joseph Clark, that it was brighter than on the 
27th. 
The following resemblances to the glows in 1883 may be 
noted :— 
(az) The distinct interval between the sunset itself, with 
illuminated lower clouds, and the glow. The latter began 20 to 
30 minutes after sunset. 
(6) The detachment from the horizon. 
(c) The shade, pink, ranging from salmon tinges (26th, due 
perhaps to London smoke-haze) to almost purple. 
(d) The clear interval between a ‘“‘glow” and ‘‘after-glow”’ 
about half an hour after sunset (noted on 28th and 29th). 
(e) The ‘“‘after-glow” growing as brilliant as the glow. 
Indeed, on the 29th it was more brilliant, and alone attracted 
attention from the ordinary observer. 
(/) The strong and prolonged ‘‘counter glow” above the 
<arth-shadow (specially noted on 28th, up to 8.50, or half an 
hour after sunset). 
(g) The prolonged ruddiness along the horizon, signs still 
femaining on 29th at 11 o'clock. 
On June 26 (Croydon) the glow arose to at least 75° ; other- 
wise 55 or so was the extreme limit. So far the pink glows 
have not been observed later than about 9.10, or, say, 50 
minutes after sunset. 
those of 1883, but perhaps with the glows two years later. 
June 30. J. EDMUND CLARK. 
The Halos of May 1, 8 and 22. 
SINcE the publication in Narure of the letters on these 
three phenomena, my attention has been directed by Prof. 
‘S. P. Thompson to the ‘* Memoire sur les Halos,’ by M. A. 
Bravais. The first of the above three halos, recorded by Prof. 
E. E. Barnard, is apparently new, unless the radius of one of 
the two circles was in reality considerably smaller than that of 
the other ; if this was the case (which from the account seems 
scarcely likely) this halo might be part of the halo depicted 
on Platé iii. Fig. 98, and described on pp. 87, 88 and following, 
and of which Bravais says that the different parts are by no 
means always visible together. 
There is no doubt that the halo described by me is sub- 
stantially the same as that depicted on Plate iii. Fig. rot, 
though it will be seen that mine has a cusp not previously 
described, whilst one of the mock suns given by Bravais is 
altogether wanting. 
Lastly, the halo described by Prof. Grenville A. J. Cole will 
be found in the same work (Plate iii. Fig. 101), where it is 
interesting to note that only one parhelion is drawn, and that is 
the one given by Prof. Cole on the left of the horizontal 
‘diameter of the smaller circle. T. C. PORTER. 
Eton, Bucks, June 30. 
NO. 1705, VOL. 66] 
In brillianey they cannot compare with | 
Matter and Motion in Space. 
Mr. WILLIAM STANLEY, an American philosopher and 
engineer, said a few days ago that the grandest words ever 
uttered by any man on this planet were spoken by Lord Kelvin 
when he said that if all the matter in the universe were reduced 
to its ultimate atoms and equally divided through all space, the 
disturbance caused by the beating of the wing of one mos- 
quito would bring about everything that we find in the material 
universe to-day. I have written to Lord Kelvin asking him 
where I can find some account of this, but he denies that he 
ever said anything of the kind. However, as Mr. Stanley 
declares that it appeared in NATURE, perhaps you can put me 
in the way of getting a copy of the paper which contains this 
remarkable utterance, which, by the way, is quite true, and if 
Lord Kelvin did not say it, I only have to say that he might well 
have been the author. Hrram S, MAxIm. 
18 Queen’s Gate Place, London, S.W., June 25. 
A Method of Treating Parallels. 
May I venture to suggest through your columns a method of 
dealing with the theory of parallels which seems to me to 
possess some advantages ? 
Since a philosophically rigid proof of their properties may be 
regarded as out of the question in the present state of our 
knowledge, the only desideratum in laying the foundation of 
this important section of geometry is an axiom the truth of which 
shall be apparent to the mind of a beginner. 
I propose that the following should be adopted, as being the 
property of parallels which is most prominent in matters of 
ordinary life, and hence to those who have not made a special 
study of geometry the most obvious :—‘‘ A straight line which 
is perpendicular to one of two parallel straight lines is 
perpendicular to the other.” 
The more general property, that parallels are equally inclined 
to any straight line which cuts them, follows immediately :— 
A H E 
B 
% F K E. 
Let AB and cD be two parallels met by a third line at E and F. 
Bisect EF at G, and draw GH perpendicular to AB and produce 
HG to meet CD at K. Then HK is perpendicular to AB and cp. 
Then in the two triangles GEH, GFK, 
angle EHG = FKG (right angles), 
angle EGH = FGK (I. 15), 
EG = GF (construction). 
.. HEG = KFG (I. 26). 
Hartley College, Southampton. S. W. RICHARDSON. 
THE FIRST FRUITS OF THE GERMAN 
ANTARCTIC EXPEDITION. 
{pee protracted voyage of the Gawss from the Elbe to 
Cape Town excited some anxiety at the time, and 
called forth a few comments unfavourable to the sailing 
power of the ship. It appears, however, that the delay 
was due mainly to the fact that many days were spent in 
carrying on oceanographical and magnetic work, although 
the change of programme which led to the abandonment 
of a visit to Ascension shows that the duration of the pas- 
sage did to some extent exceed anticipations. The Gauss, 
we may recall, left the Elbe on August 15, 1901, passed 
the Lizard on the 2oth, called at St. Vincent in the Cape 
Verde Islands on September 11, and reached Cape Town 
on November 23. The work done in various branches of 
science was discussed in a preliminary manner on board, 
and an account of it was issued in March in a paper of 
